Respiratory Support & Defense [Discontinued] by Nature's Secret

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Diabetes. Although there has been interest in using oral alfalfa for diabetes, there is insufficient reliable information about the clinical effects of alfalfa for this purpose.
• Dyspepsia. Although there has been interest in using oral alfalfa for dyspepsia, there is insufficient reliable information about the clinical effects of alfalfa for this purpose.
• Hypercholesterolemia. It is unclear if oral alfalfa seeds are beneficial in patients with hypercholesterolemia. Details: A small, uncontrolled clinical study in patients with hypercholesterolemia shows that taking heat-prepared alfalfa seeds 40 grams three times daily for 8 weeks reduces total cholesterol and low-density lipoprotein (LDL) cholesterol levels when compared to baseline (5816). The validity of these findings is limited by the lack of a control group.
• Menopausal symptoms. Although there has been interest in using oral alfalfa for menopausal symptoms, there is insufficient reliable information about the clinical effects of alfalfa for this purpose. There is insufficient reliable information available about the effectiveness of alfalfa for its other uses.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). Although there has been interest in using oral black pepper for allergic rhinitis, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Asthma. Although there has been interest in using oral black pepper for asthma, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Athletic performance. Oral black pepper has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial in untrained males shows that taking a supplement containing black pepper extract 10 mg, caffeine 400 mg, capsicum extract 66.7 mg, and niacin 40 mg as a single dose prior to exercise does not improve strength, time to exhaustion, or maximal oxygen consumption when compared with placebo (37873).
• Depression. Although there has been interest in using oral black pepper for depression, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Diarrhea. Although there has been interest in using oral black pepper for diarrhea, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Dysmenorrhea. Although there has been interest in using oral black pepper for dysmenorrhea, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Dyspepsia. Although there has been interest in using oral black pepper for dyspepsia, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Fall prevention. It is unclear if inhaling black pepper oil as aromatherapy is beneficial for fall prevention in older adults. Details: One small clinical study in older adults shows that applying black pepper oil near the right side of the nose as an olfactory stimulant improves stability while the eyes are closed during a one-minute trial when compared with the application of water. The improvement with black pepper oil is comparable to the improvement seen with the application of lavender oil (29160). It is unclear if any benefit persists after inhalation of black pepper oil.
• Fatigue. It is unclear if oral black pepper is beneficial in patients with fatigue. Details: One small clinical trial in adults with below-average energy levels shows that taking black pepper 2 grams as a single dose does not improve sustained attention, motivation to perform cognitive tasks, or feelings of mental energy and mental fatigue when compared with placebo (91731).
• Flatulence. Although there has been interest in using oral black pepper for flatulence, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Headache. Although there has been interest in using oral black pepper for headache, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Insect bite. Topical black pepper has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial shows that applying a specific product (Trikatu) containing black pepper, long pepper, and ginger, as well as camphor, eucalyptus oil, and menthol, directly to mosquito bites does not reduce papule size, erythema, edema, or pruritis when compared with a control compound containing the same base ingredients but without the pepper and ginger components (89893).
• Obesity. Although there has been interest in using oral black pepper for obesity, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Pain (chronic). Although there has been interest in using topical black pepper for chronic pain related to various etiologies, including osteoarthritis, postherpetic neuralgia, and peripheral neuropathy, there is insufficient reliable information about the clinical effects of black pepper for these conditions.
• Rhinosinusitis. Although there has been interest in using oral black pepper for rhinosinusitis, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Sexual desire. Although there has been interest in using oral black pepper for increasing sexual desire, there is insufficient reliable information about the clinical effects of black pepper for this purpose.
• Smoking cessation. It is unclear if inhaling black pepper essential oil as aromatherapy is effective for smoking cessation. Details: One small clinical trial in adult male smokers who were deprived from smoking overnight shows that inhaling a vapor from the essential oil of black pepper, as needed over a 3-hour period, reduces cigarette cravings, negative feelings, and anxiety when compared with a placebo vapor (29159). Another small clinical study in patients addicted to dipping, chewing, or smoking tobacco shows that placing a drop of black pepper essential oil on tissue paper and inhaling for 2 minutes at least three times a day for 3 days reduces nicotine cravings when compared to baseline (90502).
• Swallowing dysfunction. It is unclear if inhaling black pepper oil as aromatherapy is beneficial in patients with swallowing dysfunction. Details: One small clinical study in post-stroke residents of nursing homes shows that one minute of olfactory stimulation with black pepper oil before each meal for 30 days decreases swallowing reflex latency by 11 seconds and increases the number of swallowing movements by 3.3 when compared to baseline (29161). A small clinical trial in children with neurological disorders who were on long-term enteral nutrition shows that applying black pepper oil to the nostrils or nasal cavity for one minute improves the amount of oral intake and swallowing movement in 63% of patients. Although oral intake increased, the need for enteral nutrition was not eliminated (29162).
• Vitiligo. It is unclear if topical piperine oil, a constituent of black pepper, is beneficial in patients with vitiligo. Details: A small clinical study in patients with vitiligo shows that applying piperine oil 1% daily in addition to receiving narrowband ultraviolet B (NB-UVB) light therapy every other day for 3 months improves repigmentation more rapidly when compared with using NB-UVB alone (103820). More evidence is needed to rate black pepper for these uses.

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LIKELY EFFECTIVE

• Diabetic neuropathy. Applying a specific prescription patch containing capsaicin 8% or a specific cream containing capsaicin 0.075% can reduce pain in diabetic neuropathy. Details: Clinical research has evaluated the use of a specific patch (Qutenza, NeurogesX Inc.) containing capsaicin 8%, which is approved as a prescription medication by the US Food and Drug Administration (FDA) for the treatment of diabetic peripheral neuropathy. The research in this population shows that a single application of the patch on the painful parts of the feet for 30-90 minutes following pretreatment with topical anesthetics reduces pain for up to 12 weeks when compared with placebo (40719,96453). Patients using the patch experience reduced sleep interference and an average 28% reduction in pain, compared with a 21% reduction with placebo. Additionally, 50% of patients receiving the patch experience pain relief within 19 days, compared to 72 days for those receiving placebo (96453). A meta-analysis of the available clinical research for diabetic peripheral neuropathy found that one-time application of this patch is equally effective to duloxetine 20-120 mg daily, pregabalin 75-600 mg daily, and gabapentin 300-3600 mg daily in producing a 30% or 50% pain reduction. The dose of oral medication used in the evaluated studies did not impact the comparative efficacy of the capsaicin patch (96450). Other clinical research shows that applying cream containing capsaicin 0.075% four times daily for 8 weeks reduces pain intensity when compared with placebo in patients with diabetic peripheral neuropathy (40547,40592,40607). A meta-analysis of clinical research shows that applying cream containing capsaicin 0.075% reduces pain similarly to 5% lidocaine-medicated plaster (40674). Topical cream containing capsaicin 0.075% (Zostrix-HP, Link Medical Products Pty Ltd.) is FDA-approved as an over-the-counter (OTC) medication for this indication (272). However, applying a capsaicin lotion less frequently or with a lower concentration of capsaicin does not seem to be beneficial. A small clinical study in patients with diabetic neuropathy shows that applying a specific lotion (Capsika-75 lotion, Bangkok Drug Company) containing capsaicin 0.075% three times daily for 8 weeks improves pain to a similar degree as a placebo lotion (102277). This study was limited by a high dropout rate, high placebo effect, and poor adherence to therapy. Furthermore, cream or gel (such as Capsika-25 gel, Bangkok Drug Company) containing lower amounts of capsaicin do not appear to be effective for reducing diabetic peripheral neuropathy pain (92984).
• Pain (chronic). Topical cream containing capsaicin can reduce chronic pain associated with various conditions. Topical capsaicin is FDA-approved for this use. Details: Several clinical studies show that topically applying cream containing capsaicin, the active capsicum constituent, 0.05% to 0.075% temporarily relieves chronic pain from rheumatoid arthritis, osteoarthritis, back pain, jaw pain, psoriasis, and neuropathic conditions (12401,17701). Capsaicin, used in topical preparations, is FDA-approved for these uses (272). It can take up to 14 days for the full analgesic effect. For neuropathic pain, the number needed to treat using capsaicin 0.075% for eight weeks is 5.7 (12401). For musculoskeletal pain, for every 8.1 patients treated with capsaicin 0.025%, 1 patient would achieve at least a 50% reduction in pain (12401). Also, applying capsaicin 0.05% (Finalgon CPD Warmecreme) three times daily for 21 days seems to cause a 49% reduction in chronic soft tissue pain when compared with placebo (17701).
• Postherpetic neuralgia. Applying a specific prescription patch containing capsaicin can reduce postherpetic neuralgia pain, especially in patients with the lowest pain scores. Details: Clinical research has evaluated the use of a specific patch (Qutenza, NeurogesX Inc.) containing capsaicin 8%, which is approved as a prescription medication by the US Food and Drug Administration (FDA) for the treatment of postherpetic neuralgia. Research in this population shows that applying a single patch for 60-90 minutes reduces average pain over 24 hours by 27% to 37% for up to 12 weeks, compared to only 4.4% to 26% in patients in the control group (40659,40679,40686,40691,40719,40728,40800,92985,96451,96452). The number needed to treat to achieve at least a 30% or 50% reduction in pain intensity is 10 and 12, respectively; the number needed to treat to achieve an additional beneficial outcome over placebo at 8 weeks and 12 weeks is 9 and 7, respectively (40800,96451). The pain reduction with this patch has an onset of a few days after treatment and the effect lasts for about 5 months (92986). However, some evidence shows that the reduction in pain is only significant for patients who have had postherpetic neuralgia for at least 6 months (40686). Additionally, the reduction in pain and duration of response appears to be greatest for patients with lower pain scores and low sensitivity to light touch at baseline, as well as patients not using concomitant systemic neuropathic pain medications, whereas patients with high pain scores, high sensitivity to touch, or those using systemic neuropathic pain medications experience the smallest and least sustained reduction in pain (40728,96458). Also, other evidence suggests that this patch may be less effective at relieving postherpetic neuralgia when compared with 5% lidocaine-medicated plaster (40688).

POSSIBLY EFFECTIVE

• Back pain. Topical capsicum or capsaicin seems to be beneficial for reducing back pain. Details: A meta-analysis of generally low-quality clinical research, as well as individual studies, show that applying a capsicum-containing plaster providing 11 mg of capsaicin per plaster or 22 mcg of capsaicin per square centimeter of plaster to the back once daily in the morning for 4-8 hours reduces low back pain when compared with placebo (15259,15260,15261). Applying capsaicin 0.05% (Finalgon CPD Warmecreme) three times daily for 21 days seems to cause a 58% reduction in low back pain when compared with placebo (17701). Also, in a mixed group of patients with acute back or neck pain, a large clinical trial shows that four topical applications with a gel containing capsaicin 0.075% with diclofenac 2% every 12 hours modestly reduces pain on motion when compared with diclofenac alone or placebo. The number of patients with at least a 50% reduction in pain from baseline was modestly higher. Capsaicin 0.075% was similarly effective alone and when combined with diclofenac 2% (105202). However, only about half of the patients in this study had back pain.
• Cluster headache. Intranasal capsaicin seems to be beneficial for preventing cluster headaches. Its effect in the treatment of cluster headache is unclear. Details: Some clinical research shows that using the capsicum constituent capsaicin intranasally reduces the frequency of episodic or chronic cluster headache attacks (14323,14351,14352,14358). Capsaicin suspensions of 0.1 mL of a 10 mM suspension, providing 300 mcg/day of capsaicin, has been applied to the ipsilateral nostril. Applications are continued once daily until a burning sensation is no longer experienced (14351,14358). Intranasal application of capsaicin 0.025% (Zostrix, Rodlen Laboratories) might also decrease symptom severity during an acute cluster headache attack. Clinical research shows that daily treatment for 7 days decreases symptom severity over the following week (14353). Ipsilateral, or same side, nostril application of capsaicin appears to be more effective than contralateral application (14351). Due to severe pain associated with intranasal capsaicin administration, pretreatment with intranasal local anesthetic is usually used.
• Nonallergic rhinitis. Intranasal capsaicin in a dose of at least 0.1 mM seems to improve symptoms of nonallergic rhinitis. It is unclear if lower doses of capsaicin are beneficial. Details: Clinical research shows that repeated intranasal in-clinic treatments with capsaicin, the active capsicum constituent, or with capsicum oleoresin, over a period of one to three days, can significantly decrease symptoms of non-allergic, non-infectious perennial rhinitis symptoms (14328,14357,15016,40595,105204,105205). A decrease of symptoms has been observed for up to 6-9 months following these treatments (14328,14357). The following doses have been used: capsaicin 0.15 mg per dose for up to 7 doses over a 14-day period (14328), capsaicin 0.0033 mol once weekly for 5 weeks (14357), capsaicin 15 mcg/0.1 mL applied three times daily for 3 days (15016), and capsaicin 1-4 mcg per puff, applied 3 times in each nostril daily for 3 days (40595). Due to severe pain associated with intranasal capsaicin administration, pretreatment with intranasal local anesthetic is usually used. Personal use of an intranasal spray with a lower dose of capsaicin might also be effective. Clinical research shows that two 0.4 mL puffs with an intranasal spray in each nostril daily for 4 weeks providing capsaicin 0.01 mM, but not 0.001 mM, is more effective than placebo for reducing symptoms of idiopathic rhinitis. This benefit is maintained for an additional 8 weeks. This protocol was at least as effective as receiving five repeated hourly intranasal spray treatments in hospital with capsaicin 0.1 mM (105204).
• Osteoarthritis. The American College of Rheumatology (ACR) conditionally recommends topical capsaicin for knee osteoarthritis, but not for hip or hand osteoarthritis. Details: A meta-analysis of 4 preliminary clinical trials shows that using topical capsaicin 0.025% four times daily has modest benefit for osteoarthritis when compared with placebo. Using capsaicin 0.0125% doesn't seem to be effective (102408). The American College of Rheumatology (ACR) conditionally recommends topical capsaicin for knee osteoarthritis. However, it does not recommend its use for hip osteoarthritis due to the depth of the joint beneath the skin surface, nor for hand osteoarthritis, due to the risk for contamination of the eye (102114).
• Pain (acute). Topical capsicum seems to be beneficial for reducing acute pain due to trauma. Details: Clinical research in patients with trauma-related acute pain shows that topical application with a gel (Sanli Gel) containing capsaicin 0.05% three times daily for 3 days reduces pain by at least 50% in 87% of patients, compared with 63% of those using a piroxicam gel 0.5% (Felden). There was also a significantly greater number of patients with a final pain score of 4 or less. In the capsaicin group, only 12% of patients did not achieve either of these endpoints, compared with 31% in the group receiving piroxicam (105197).
• Postoperative nausea and vomiting (PONV). Applying topical capsicum to acupoints seems to be beneficial for preventing PONV. Details: Clinical research shows that applying a capsicum-containing plaster to acupoints on the hand and forearm 30 minutes prior to anesthesia and leaving in place for 6-8 hours daily for up to 3 days after surgery reduces the incidence of PONV by about 29% to 36% when compared to control (40405,40483,40610). Plasters used in these studies included Sinsin PAS (Sinsin Pharm Co.), which is standardized to contain capsicum 345.8 mg and capsicum tincture 34.58 mg per sheet (40405,40610); and Johnson's Perforated Capsicum Plaster (Johnson & Johnson Ltd.), which is standardized to contain capsicum oleoresin 1% w/w (40483).
• Postoperative pain. Applying topical capsicum-containing plaster to acupoints seems to be beneficial for reducing postoperative pain. It is unclear if a capsicum patch or capsaicin instillation prior to wound closure is beneficial for reducing postoperative pain. Details: Some clinical research shows that applying a capsicum-containing plaster to acupoints on the hands or near the knees of adults or children 30 minutes prior to anesthesia, and leaving in place for 6-8 hours daily for up to 3 days after surgery, reduces the amount of rescue analgesics needed by 29% to 39% within the first 24 hours and by 16% to 19% within the first 48 hours when compared to control (40405,40483,40520,40524,40610). The capsicum-containing plaster used in these studies (Sinsin PAS, Sinsin Pharm Co.) is standardized to contain capsicum 345.8 mg and capsicum tincture 34.58 mg per sheet (40520,40610). Other preliminary clinical research shows that applying a single patch containing the capsicum constituent capsaicin 8% (Qutenza, NeurogesX Inc.) for 30-60 minutes leads to an improvement in overall health status and an average 22% reduction in pain that lasts up to 12 weeks in patients with postoperative and posttraumatic neuropathic pain. Patches were applied to various parts of the body, including the legs, torso, feet, hands, arms, head, and neck, and the reduction in pain continued with the use of a second and third patch application. The validity of these findings is limited by the lack of a control group (96452). Other clinical evidence suggests that instilling capsaicin 15 mg during surgery immediately prior to wound closure reduces the need for pain medication for up to 2 weeks postoperatively when compared with placebo (40741).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). It is unclear if intranasal capsaicin is beneficial for preventing allergic rhinitis symptoms. Details: Preliminary clinical research shows that intranasal treatment with cotton wads soaked in the active capsicum constituent capsaicin 30 mcM, applied for 15 minutes and repeated over two days, reduces the severity of experimentally-induced allergic rhinitis. The severity of symptoms seems to be reduced for up to 2 months after treatment (14324). However, contradictory research shows that patients with allergic rhinitis caused by house dust mites do not have significantly improved symptoms after using a capsaicin solution providing 0.15 mg/dose for up to 7 doses over a 14-day period when compared with placebo (14360).
• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Although there is interest in using oral capsicum for ALS, there is insufficient reliable information about the clinical effects of capsicum for this condition.
• Athletic performance. It is unclear if oral capsaicin is beneficial for improving athletic performance; the available research is limited to small, conflicting studies. Details: Several small clinical studies in physically active young adults show that taking capsaicin might improve some measures of athletic performance, but results are mixed overall (99409,99410,102276,105191,105198,105200). A meta-analysis of these and several other small clinical studies shows that taking the capsicum constituents capsaicin or capsiate 45 minutes before exercise improves measures of muscular endurance but does not improve aerobic endurance when compared with placebo. Doses of the capsicum constituents ranged from 1.2-24 mg, with most studies assessing a single 12 mg dose (111515). The included studies have a number of methodological problems that limit the validity of the findings, such as a small sample size, short study duration, and insufficient blinding. Also, most of the study participants were male. Other small clinical studies not included in the meta-analysis also show conflicting results. One small clinical study in untrained young adults undergoing resistance training shows that taking capsiate, a capsaicin analog, 6 mg orally twice daily for 6 weeks improves upper body, but not lower body, weightlifting performance when compared with placebo (109024). However, another small clinical trial in experienced male athletes shows that taking cayenne (GNC Nature's Fingerprint Cayenne Herbal Supplement) 3 grams, providing capsaicin 25.8 mg, daily for 7 days does not improve sprint time, rate of perceived exertion, or muscle soreness over three days when compared with placebo (105206). Capsicum has also been evaluated in combination with other ingredients. One small clinical study in untrained males shows that taking a supplement containing capsicum extract 66.7 mg, caffeine 400 mg, black pepper extract 10 mg, and niacin 40 mg prior to exercising does not improve strength, time to exhaustion, or maximal oxygen consumption when compared with placebo (37873).
• Burning mouth syndrome. It is unclear if applying topical capsaicin in the mouth is beneficial for burning mouth syndrome. Details: Preliminary clinical studies show that using 15 mL of a mouth rinse containing the active capsicum constituent capsaicin 0.02% for 30 seconds daily for 7-21 days modestly decreases burning discomfort when compared to baseline in patients with burning mouth syndrome (92991,105195). Other preliminary clinical research shows that applying 0.5 mL of a gel containing capsaicin 0.01% or 0.025% to the tongue three times daily for 14 days modestly reduces pain when compared to baseline in patients with burning mouth syndrome. The gel is spread with a cotton swab, and no food or drink is consumed for 30 minutes after application (96456). The validity of these findings is limited by the lack of a control group, the small number of patients, and occasionally unclear statistical comparisons.
• Cancer. It is unclear if eating more chili is beneficial for preventing mortality due to cancer. Details: Population research has found that consuming chili more than four times weekly is not associated with a reduced odds of cancer mortality (105208). Also, other population research has found that any consumption of hot red chili peppers is not associated with a reduced odds of mortality related to cancer (105210).
• Cannabinoid hyperemesis syndrome (CHS). Preliminary clinical research suggests that topical capsaicin might be beneficial for reducing symptoms of CHS. Details: One small clinical study in adults presenting to an emergency department (ED) with CHS shows that applying 5 grams of a cream containing capsaicin 0.1% to the abdomen modestly reduces nausea severity at 60 minutes, but not 30 minutes, when compared with a placebo cream. Nausea was completely resolved in 29% of patients, compared with 0% of those using the placebo cream. However, there was no difference in vomiting at 30 or 120 minutes (105193). This study may not have been adequately powered to detect a difference in some of these outcomes. A meta-analysis of two small, low-quality studies involving the topical use of capsaicin on the abdomen, chest, and possibly back, shows that the mean time to resolution of symptoms was 326 minutes and the mean length of stay in the emergency department was 379 minutes. However, it is unclear how these times compare to the use of placebo or standard antiemetics. This study also conducted a systematic review of the available literature, which indicates that the creams most commonly used in research provide 0.025% to 0.1% capsaicin (105201). Two low-quality, retrospective reviews also suggest that capsaicin cream may be beneficial for CHS. A retrospective review of patients in the ED with CHS has found that applying capsaicin cream 0.025% is associated with a 39% shorter time to discharge when compared with control. Patients treated with capsaicin also required fewer additional rescue treatments when compared with control (109021). Another retrospective review of patients in the ED with CHS also suggests that capsaicin cream 0.025% modestly reduces abdominal pain when compared with baseline. However, 47% and 28% of patients, respectively, received additional antiemetics or an opioid after the use of the cream (105345).
• Cardiovascular disease (CVD). It is unclear if eating more chili is beneficial for preventing mortality due to CVD. Details: Population research has found that consuming chili more than four times weekly is associated with a 34% reduced odds of CVD mortality when compared with never or rarely consuming chili, as well as 44% and 61% reduced odds of ischemic heart disease and cerebrovascular death, respectively (105208). Other population research has found that consumption of hot red chili peppers is not associated with a reduced odds of mortality related to CVD when compared with not eating hot red chili peppers (105210).
• Diabetes. It is unclear if oral capsaicin is beneficial for gestational diabetes. Details: Preliminary clinical research shows that taking chili powder containing capsaicin 5 mg daily for 4 weeks modestly reduces total cholesterol levels and reduces postprandial blood glucose levels by an average of 36 mg/dL and postprandial insulin levels by an average of 14 IU/L in patients with gestational diabetes. Compared to a placebo group, these changes are significant. However, capsaicin intake does not alter fasting plasma glucose or insulin levels (96457).
• Dry skin. It is unclear if oral capsicum is beneficial for dry skin. Details: Preliminary clinical research in adult females with low skin moisture shows that taking paprika oil extract 400 mg, standardized to include 9 mg of xanthophyll, orally daily for 4 weeks improves skin moisture and viscoelasticity scores, but not the number of wrinkles, when compared with control (109026).
• Dyslipidemia. It is unclear if oral capsicum is beneficial for reducing lipid levels. Details: A meta-analysis of three or four mainly small clinical trials in healthy adults shows that taking capsicum does not improve levels of triglycerides, total cholesterol, or high-density lipoprotein (HDL) cholesterol when compared with no treatment or placebo. However, there was a small to moderate effect on levels of low-density lipoprotein (LDL) cholesterol. Freshly chopped chili or fermented red pepper were studied for 4 and 12 weeks, respectively (105194). It is unclear if capsicum can lower lipid levels in patients with dyslipidemia or hyperlipidemia.
• Dyspepsia. It is unclear if oral capsicum is beneficial for dyspepsia. Details: Preliminary clinical research shows that taking red pepper powder 2.5 grams daily in three divided doses for 5 weeks reduces symptoms of functional dyspepsia when compared with placebo. However, in some patients, there seems to be a worsening of symptoms prior to any improvement (12410).
• Fibromyalgia. It is unclear if oral capsicum is beneficial for fibromyalgia. Details: Preliminary clinical research shows that applying cream containing the active capsicum constituent capsaicin 0.025% four times daily to tender points for 4 weeks reduces localized tenderness in patients with fibromyalgia (7038). Other preliminary clinical research shows that applying capsaicin 0.075% cream (Sensedol) three times daily to tender points for 6 weeks in addition to standard therapy increases the pain threshold when compared with standard therapy in patients with severe fibromyalgia (92979). However, capsaicin does not appear to reduce overall pain or improve physical function in patients with fibromyalgia (7038,92979). Also, the long-term effects of capsaicin on fibromyalgia-related pain are unclear.
• Gastroesophageal reflux disease (GERD). Although there is interest in using oral capsicum for GERD, there is insufficient reliable information about the clinical effects of capsicum for this condition.
• HIV/AIDS-related peripheral neuropathy. It is unclear if topical capsaicin is beneficial for this condition. Details: There is conflicting evidence regarding the effects of Qutenza (NeurogesX Inc.), which contains the active constituent of capsicum, capsaicin 8%. Although some research shows it reduces pain in patients with HIV and peripheral neuropathy (22395), other research shows no significant benefit (40746). A meta-analysis of results from both of these studies shows that applying a single capsaicin 8% patch for 30-90 minutes reduces pain intensity by at least 30% in about 30% more patients when compared to control (40800). Additional meta-analyses of the results from these two studies suggests that pain reduction with capsaicin begins a few days after treatment and lasts for about 5 months, with a number needed to treat of 11 to achieve at least a 30% reduction in pain intensity (92986,96451). Reduction in pain and duration of response appears to be greatest for females with lower pain scores at baseline, whereas males with high pain scores at baseline experience the smallest and least sustained reduction in pain (96458). Some research has also evaluated topical capsaicin 0.075%. One small clinical study shows that applying this cream does not relieve symptoms of HIV-associated peripheral neuropathy when compared with placebo (3891).
• Hypertension. It is unclear if oral capsicum is beneficial for lowering blood pressure. Details: Two meta-analyses of small clinical trials show that taking capsicum as freshly chopped chili, fermented red pepper, red pepper capsules, or capsinoid capsules orally daily for 4-12 weeks does not reduce systolic or diastolic blood pressure when compared with control. However, most subjects included in these clinical trials did not have hypertension (105194,109025).
• Intermetatarsal neuroma. It is unclear if injecting capsaicin into the third intermetatarsal space is beneficial for intermetatarsal neuroma. Details: Clinical research in adults with intermetatarsal neuroma shows that a single injection of capsaicin 0.1 mg into the third intermetatarsal space 5 minutes after administration of 2 mL of lidocaine 2% with epinephrine leads to a modest reduction in pain at weeks 1 and 4, but not weeks 2 and 3, when compared with placebo. Capsaicin also reduces the extent to which pain interferes with walking and mood, but not with work, sleep, relationships, or general activity (96454).
• Irritable bowel syndrome (IBS). It is unclear if oral capsicum is beneficial for IBS. Details: Preliminary clinical research shows that taking ground guajillo chili 1 gram, containing capsaicin 0.112%, with each meal for 7 days does not reduce symptoms of IBS (12403). A small clinical study shows that taking chili (Nguan Soon Co., Ltd.) 2.1 grams, providing 2.5 mg capsaicin, daily before meals for 6 weeks does not improve abdominal burning, fecal urgency, or abdominal pain or bloating after a spicy meal. However, there was a modest reduction in abdominal burning after a spicy meal (105207). This study may not have been adequately powered to detect a difference in some of these outcomes.
• Laryngitis. Although there is interest in gargling with capsicum for laryngitis, there is insufficient reliable information about the clinical effects of capsicum for this condition.
• Motion sickness. Although there is interest in oral capsicum for motion sickness, there is insufficient reliable information about the clinical effects of capsicum for this condition.
• Myofascial pain syndrome. It is unclear if topical capsaicin is beneficial for myofascial pain syndrome. Details: Preliminary clinical research shows that applying a specific capsaicin cream (Dipental Cream, Dalim BioTech) containing capsaicin 0.25 mg/gram along with a ketoprofen 30 mg patch (KetotopVRPlaster, Pacific Pharma) to the trapezius does not reduce pain when compared with a ketoprofen patch alone in patients with myofascial pain (92983).
• Neck pain. It is unclear if topical capsaicin is beneficial for neck pain. Details: In a group of patients with acute back or neck pain, a large clinical trial shows that four topical applications with a gel containing capsaicin 0.075% with diclofenac 2% every 12 hours modestly reduces pain on motion when compared with diclofenac alone or placebo. The number of patients with at least a 50% reduction in pain from baseline was modestly higher. Capsaicin 0.075% was similarly effective alone or when combined with diclofenac 2% (105202). However, only about half of the patients in this study had neck pain.
• Neuropathic pain. It is unclear if topical capsicum is beneficial for neuropathic pain. Details: A very small study in adults with neuropathic pain secondary to spinal cord injury shows that applying a patch containing the capsicum constituent capsaicin 8% for 60 minutes daily to the affected area for 12 weeks reduces pain at weeks 2 and 4 and improves mobility, but not quality of life, for up to 12 weeks when compared with placebo (111517). The validity of these findings is limited by insufficient blinding and the small sample size.
• Obesity. It is unclear if oral capsicum is beneficial for obesity. Details: A meta-analysis of 3-5 small clinical trials shows that taking capsicum does not reduce body weight, body fat, or body mass index (BMI) in individuals with a BMI of at least 25 kg/m2 when compared with placebo or no treatment. Freshly chopped chili, fermented red pepper, or capsicum constituents were studied for 4-12 weeks (105194). In one clinical trial included in the analysis, taking capsinoids 3 mg twice daily 30 minutes prior to eating for 12 weeks reduced abdominal fat by about 1%, but did not significantly reduce body weight, when compared with placebo (40599). In overweight individuals, one small clinical trial shows that taking a specific chili extract 200 mg, formulated with fenugreek dietary fiber for sustained release (Capsifen, Akay Natural Ingredients), providing capsaicinoids 4 mg daily for 28 days reduces body weight and BMI by about 2% when compared with placebo. There was no effect on blood pressure (105196). Capsicum has also been evaluated in combination with other ingredients, with some evidence of benefit. One study evaluated a combination product (Prograde Metabolism) containing capsicum extract (Capsimax, OmniActive Health Technologies), raspberry ketone (Razberi K, Integrity Nutraceuticals), caffeine, garlic root extract, ginger root extract, bitter orange fruit (Advantra Z, Nutratech Inc), L-theanine, and black pepper fruit extract (Biperine, Sabinsa Corporation) twice daily for 8 weeks (40802).
• Overall mortality. Eating chili may be beneficial for preventing mortality. It is unclear if taking capsicum supplements is beneficial for preventing overall mortality. Details: Population research has found that consuming chili is associated with a reduced risk of overall mortality. In one study, eating chili more than four times weekly was associated with a 23% reduced odds of overall mortality when compared with never or rarely consuming chili (105208). Other population research has found that any consumption of hot red chili peppers is associated with a 13% reduced odds of mortality when compared with not eating these peppers (105210). Also, eating spicy foods at least once each week, consisting mainly of fresh chili pepper, dried chili pepper, chili sauce, or chili oil, was associated with at least a 10% reduced risk of death when compared with eating these foods less than once a week (105211).
• Peptic ulcers. It is unclear if oral capsicum is beneficial for peptic ulcers. Details: Population research has found that eating capsicum fruit (chili) an average of 24 times per month is associated with a reduced likelihood of having an ulcer when compared with eating chili an average of 8 times per month. This applies to chili in the form of chili powder, chili sauce, curry powder, and other chili-containing foods (12053). However, clinical research shows that consuming chili peppers 1 gram three times daily for 4 weeks does not improve duodenal ulcer healing when compared to control (40828).
• Peripheral neuropathy. Preliminary clinical research suggests that topical capsaicin might be beneficial for reducing peripheral neuropathy pain. Details: Preliminary clinical research shows that applying patches containing the capsicum constituent capsaicin 8% (Qutenza, NeurogesX Inc.) reduces pain in people with non-diabetic peripheral neuropathy (96452,111516). Up to four patches, applied to different painful areas, are used at one time and are left in place for 30 minutes on the feet, or 60 minutes on other parts of the body such as the legs, torso, hands, arms, head, or neck (96452). After an interval of at least 90 days, treatment can be repeated, with new patches applied for 30-60 minutes (99407). There is an average 27% reduction in pain when compared to baseline, lasting up to 12 weeks (96452). Another similar study reported a decrease of 1 point, on a 10-point pain scale, in the typical daily pain intensity (99407). The validity of these findings is limited by methodological problems, including the lack of control groups. Further research shows that using a single application of up to four capsaicin 8% patches for 30-60 minutes, or taking pregabalin orally, 150-600 mg in 2-3 divided doses daily for 8 weeks, reduces the intensity and area of dynamic mechanical allodynia (DMA, pain evoked by light brushing of the skin) in people with non-diabetic peripheral neuropathy. Complete resolution of DMA occurred in 24% of people using the patches, and 12% of those taking pregabalin (99408). The validity of these findings is limited by methodological problems, including a lack of blinding.
• Prurigo nodularis. It is unclear if topical capsaicin is beneficial for prurigo nodularis. Details: Preliminary clinical research shows that applying a cream containing the active capsicum constituent, capsaicin 0.025% to 0.3%, 4-6 times daily improves burning sensations, erythema, pruritus, and healing of skin lesions over a period of 2 weeks to 33 months when compared to baseline. Symptoms may return after discontinuation of therapy (10650).
• Sinonasal polyposis. It is unclear if intranasal capsaicin is beneficial for sinonasal polyposis. Details: Preliminary clinical research in patients with severe sinonasal polyposis shows that intranasal application of 0.5 mL of a 30 mmol/L capsaicin solution to each nostril for 3 days, followed by 0.5 mL of a 100 mmol/L capsaicin solution for 2 days, can cause significant subjective improvement in symptoms as well as objective improvement in nose/sinus air volume and endoscopy scores; however, capsaicin does not seem to significantly affect eosinophil cationic protein levels (14359).
• Swallowing dysfunction. Preliminary research shows that oral capsaicin might be beneficial for improving swallowing ability. Details: Preliminary clinical research shows that elderly patients at risk for aspiration pneumonia due to swallowing dysfunction have improved swallowing reflexes after dissolving a lozenge containing capsaicin 1.5 mcg in the mouth before each meal when compared with using a placebo lozenge (13100). Preliminary clinical research also shows that capsaicin may be beneficial in patients with swallowing dysfunction due to stroke (102278,105192). One study shows that taking 1 mL of nectar containing capsaicin 150 mcM/L with each meal daily for 3 weeks, in addition to thermal tactile stimulation, improves eating and swallowing when compared with using thermal tactile stimulation and placebo nectar (102278). Another study shows that 20 minutes of stimulation with an ice swab containing capsaicin 0.15 mM before lunch and dinner daily for three weeks modestly improves the ability to swallow water when compared with ice stimulation alone. After treatment, approximately 70% of those using the capsaicin ice were able to drink the water without choking, compared with only 33% in those using ice alone (105192). Capsaicin solution has also been administered by nebulizer. A clinical study in patients with swallowing dysfunction secondary to hemorrhagic stroke shows that inhaling capsaicin solution twice daily for one week reduces the incidence of post-swallow residue and pulmonary infection and increases number of coughs in response to capsaicin compared with placebo. However, treatment with nebulized capsaicin does not reduce the number of patients with swallow or cough reflexes compared with control (111518). More evidence is needed to rate capsicum for these uses.

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POSSIBLY EFFECTIVE

• Diabetes. Oral fenugreek seed seems to improve glycemic control in type 2 diabetes. Details: Meta-analyses of up to14 clinical trials in patients with type 2 diabetes or other metabolic conditions show that taking fenugreek with or without standard diabetes medications lowers fasting glucose by approximately 14-27 mg/dL, 2-hour postprandial glucose by 21-30 mg/dL, and glycated hemoglobin (HbA1c) by 0.5-1.2% when compared with placebo (90112,96065,105016,111503,112120,113499,113604,113630). The most effective doses and formulations seem to include powdered seed or debitterized seed powder 100 grams daily, taken as capsules or added to meals, for up to 3 years or seed hydroalcoholic extract about 1 gram daily for up to 2 months (90112,96065,105016,111503,112120,113499). The validity of these effects is limited by high heterogeneity and low quality in the included studies. Most research also shows that fenugreek seed lowers total cholesterol levels and triglycerides in patients with diabetes, but has inconsistent effects on low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol (96065,102252,113630). Some research shows that taking fenugreek in combination with other ingredients also seems to improve glycemic indices in people with diabetes. These combination products have combined fenugreek with guar gum and gymnema (10284) or millets and legumes (9784). Limited research has also evaluated fenugreek in type 1 diabetes. In one small clinical study, taking 50 grams of defatted fenugreek seed powder twice daily with meals for 10 days reduced 24-hour urine glucose levels by 54% when compared to baseline (622). The validity of this finding is limited by the lack of a comparator group.
• Dysmenorrhea. Oral fenugreek seed might help to reduce menstrual pain. Details: A meta-analysis of 2 clinical studies in patients with moderate to severe dysmenorrhea shows that taking fenugreek capsules 5.4-6.3 grams daily for 3 days beginning on the first day of the menstrual cycle for 2 consecutive months reduces pain intensity when compared with placebo (113628). However, low-quality clinical studies show that fenugreek seed is not more effective for reducing menstrual pain when compared with garden cress or the anti-inflammatory medication mefenamic acid (113628).
• Sexual arousal. Oral fenugreek seed might help to improve sexual arousal. Details: Clinical research shows that taking a specific fenugreek seed extract (Testofen, Gencor Pacific Ltd) 600 mg daily for 12 weeks increases sexual function by 15% over baseline, compared with no change in the placebo group; the main benefits were in sexual arousal and drive. Morning erection and sexual frequency also improve by 2- to 3-fold (93419). Another clinical study in healthy males shows that taking the same fenugreek seed extract 600 mg daily in combination with magnesium 34 mg, zinc 30 mg, and vitamin B6 10 mg for 6 weeks, improves a composite of symptoms such as sexual cognition, sexual arousal, sexual behavior, and orgasm. The overall improvement in the composite score was 23%, compared with a worsening in the placebo group (93421).
• Sexual dysfunction. Oral fenugreek seed extract might help to improve sexual dysfunction. Details: Clinical research shows that taking a specific fenugreek seed extract (Libifem, Gencor Pacific Ltd.) 300 mg twice daily for two menstrual cycles improves sexual function in healthy pre-menopausal adults with low sex drive. In one clinical trial, overall improvement based on a composite of symptoms was 26% in the fenugreek group, compared with only 2% in the placebo group. Individual scores for sexual cognition, arousal, behavior, drive, and orgasm were all improved. Patients taking fenugreek also had an increased frequency of sexual activity from 1-2 times per month to once per week, compared to no change in the placebo group (93420). Other clinical research in males aged 35-60 years with symptomatic hypogonadism shows that taking a specific fenugreek seed extract (Furosap; Chemical Resources) 500 mg daily after breakfast for 12 weeks improves sexual arousal, mental alertness, and mood when compared with baseline. This fenugreek seed extract was fortified with 20% protodioscin; the other constituents were not specified (108700). The validity of this finding is limited by the lack of comparator group.

POSSIBLY INEFFECTIVE

• Benign prostatic hyperplasia (BPH). Oral fenugreek extract does not seem to improve BPH symptoms. Details: A clinical study in healthy adults with BPH shows that taking a specific fenugreek extract (Testofen, Bluegum Pharmaceuticals) 300 mg twice daily for 12 weeks does not improve BPH symptoms when compared with placebo (102253).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alopecia areata. Although there is interest in using oral fenugreek for alopecia areata, there is insufficient reliable information about the clinical effects of fenugreek for this condition.
• Alzheimer disease. It is unclear if oral fenugreek seed extract is beneficial for Alzheimer disease. Details: A moderate-sized study in adults with mild to moderate Alzheimer disease shows that taking fenugreek seed extract 5 mL daily for 4 months modestly improves memory but does not improve depression or quality of life measures when compared with placebo (113498).
• Athletic performance. It is unclear if oral fenugreek seed is beneficial for improving athletic performance. Details: Research evaluating fenugreek for athletic performance has yielded inconsistent results. The reason for these mixed findings is unclear. A meta-analysis of clinical studies in healthy adult males shows that taking fenugreek or fenugreek seed extract 250-600 mg daily for 8-12 weeks does not improve upper or lower body strength, lean body mass, or fat mass when compared with placebo (113629). Other small clinical studies in resistance-trained young males show that taking a fenugreek supplement (AI or Torabolic, Indus Biotech; Fenu-FG, Indus Biotech Private Limited) for 8 weeks in addition to training does not improve power or strength when compared with placebo, but modestly improves some measures, such as leg and bench press performance, and slightly reduces body fat (18352,18353,93423). While most clinical research is in males, a clinical study in healthy adult females shows that taking fenugreek (Libifem, Gencor Pacific Ltd.) 600 mg daily for 8 weeks in conjunction with resistance training improves lower body strength, lean body mass, and fat mass when compared with placebo. However, there was no change in upper body strength, endurance, or power when compared with placebo (113631).
• Atopic dermatitis (eczema). Although there is interest in using topical fenugreek for eczema, there is insufficient reliable information about the clinical effects of fenugreek for this condition.
• Cough. Although there is interest in using oral fenugreek for cough, there is insufficient reliable information about the clinical effects of fenugreek for this purpose.
• Gastroesophageal reflux disease (GERD). It is unclear if oral fenugreek fiber is beneficial for improving heartburn symptoms. Details: A small clinical study in patients with frequent heartburn shows that taking a specific fenugreek fiber product (FenuLife, Frutarom Belgium), 2 grams twice daily 30 minutes before the two biggest meals of the day, improves heartburn after one week of treatment and continuing through the 2-week study period. Fenugreek seemed to be similarly effective to ranitidine 75 mg twice daily (17372).
• Gout. Although there is interest in using topical fenugreek for gout, there is insufficient reliable information about the clinical effects of fenugreek for this condition.
• Hyperlipidemia. Small clinical studies suggest that oral fenugreek supplements might be beneficial for improving lipid levels. Details: Overall, fenugreek powdered seed seems to modestly reduce lipid levels in people with or without hyperlipidemia; however, most studies have been low-quality, small, and exploratory. Meta-analyses of these studies show that fenugreek reduces total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides, and increases high-density lipoprotein (HDL) cholesterol (103283,103284). Powdered fenugreek seed has been studied in doses of 0.5-100 grams daily for 10 days to 3 years. While some studies show modest improvement, others show no benefit (622,7389,9783,18359,18361,18362,102252,103283,103284,113497).
• Hypertension. Analysis of small clinical studies suggests that oral fenugreek might slightly improve systolic blood pressure (SBP). Details: A meta-analysis of 6 small clinical studies in healthy adults or those with diabetes, prediabetes, or metabolic syndrome shows that taking fenugreek seed 0.5-50 grams daily for 6-144 weeks reduces SBP by 3.5 mmHg but does not improve diastolic blood pressure (DBP) when compared with placebo. However, subgroup analysis suggests that taking fenugreek at a dose of 15 grams or more daily or for a duration of 12 weeks or less modestly reduces DBP (112110).
• Impaired glucose tolerance (prediabetes). It is unclear if oral fenugreek is beneficial in patients with prediabetes. Details: A small clinical study in adults with prediabetes shows that taking a specific fenugreek seed extract (Trigogen, Gencor Pacific Ltd.) 250 mg twice daily for 12 weeks reduces fasting blood glucose and postprandial blood glucose but not glycated hemoglobin (HbA1c), fasting insulin, or postprandial insulin when compared with placebo (113497). Another small clinical trial in patients with prediabetes shows that taking fenugreek seed extract 200 mg, bergamot extract 500 mg, and olive leaf extract 100 mg daily for 6 months does not improve glycated hemoglobin or fasting blood glucose when compared with placebo (102251).
• Joint pain. Although there is interest in using oral fenugreek for joint pain, there is insufficient reliable information about the clinical effects of fenugreek for this condition.
• Lactation. Small clinical studies suggest that oral fenugreek, either as a supplement or tea, might increase lactation. Details: A network meta-analysis of 4 small clinical trials shows that taking fenugreek shortly after delivery may modestly increase breast milk production when compared with placebo. Patients in the included studies took fenugreek 1-2 grams as capsules or tea up to 3 times daily for 21-244 days. In most cases, fenugreek treatment was initiated one or two days after delivery. However, fenugreek might be less beneficial for breast milk production when compared with the natural ingredients Indian borage or palm date (96067). Fenugreek has also been used in combination with other ingredients. A small clinical study suggests that drinking a specific herbal tea containing fenugreek. hibiscus, fennel, rooibos, vervain, raspberry, goat's rue, and fennel oil (Humana Still-Tee, Humana, Germany) 200 mL three times daily modestly increases milk production when compared with placebo (22569). Another study in exclusively breastfeeding parents of 2-month-old infants shows that eating lactation cookies containing fenugreek, oatmeal, brewer's yeast, and flaxseed meal daily for 30 days do not improve milk production, perceived insufficiency, or breastfeeding self-efficacy when compared with control (112116).
• Male infertility. It is unclear if oral fenugreek seed is beneficial for improving sperm quality in males with infertility. Details: A small clinical study in healthy male patients ages 20-30 years with oligospermia shows that taking fenugreek seed oil 12 macro drops orally three times daily for 4 months improves sperm count from 6.2 million to 20.1 million, increases sperm motility from 43% to 61%, and reduces sperm abnormality from 68% to 53% when compared with baseline. However, taking the remaining fenugreek seed components 10 grams three times daily for 4 months does not seem to have this effect (90119). The validity of this finding is limited by the lack of a comparator group.
• Menopausal symptoms. It is unclear if oral fenugreek seed is beneficial for improving menopausal symptoms. Details: A small clinical study in perimenopausal patients shows that taking a specific fenugreek seed extract (FenuSMART) 250 mg, standardized to protodioscin 10.3%, trigonelline 3.1%, and total saponin 42.6%, twice daily with meals for 42 days does not improve menopausal symptoms when compared with placebo. However, there was a non-significant trend to reduced hot flashes, night sweats, depression, and insomnia in the treatment group (105000). This study was funded by the supplement manufacturer.
• Metabolic syndrome. It is unclear if oral fenugreek seed is beneficial for metabolic syndrome. Details: A meta-analysis of 29 small clinical studies in healthy adults or those with type 2 diabetes or other metabolic conditions shows that taking fenugreek at doses ranging from 25 mg to 60 grams daily for up to 144 weeks reduces fasting blood glucose by 17 mg/dL, triglycerides by 20 mg/dL, waist circumference by 2.5 cm, and systolic blood pressure by 3.5 mmHg and increases high-density lipoprotein cholesterol by 3.5 mg/dL when compared with control. However, no effect was found on diastolic blood pressure or body mass index (113500).
• Muscle strength. It is unclear if oral fenugreek seed is beneficial for increasing muscle strength. Details: A small study in healthy, active males shows that taking fenugreek seed extract 400 mg or 500 mg daily for 60 days increases grip strength when compared with placebo (103285).
• Myalgia. Although there is interest in using topical fenugreek for myalgia, there is insufficient reliable information about the clinical effects of fenugreek for this condition.
• Obesity. Small clinical studies suggest that oral fenugreek seed or fiber may increase satiety and decrease caloric intake. Details: Two small clinical studies in overweight and normal weight males shows that taking fenugreek seed extract modestly reduces daily fat intake. At a dose of 392 mg three times daily for 2-6 weeks, fat intake is reduced by 13% to 17%. However, a lower dose of 196 mg three times daily appears to be ineffective. Neither of the doses affect weight, appetite, or satiety (18348,18349). Another small clinical study in obese adults shows that adding 8 grams of fenugreek fiber powder (FenuLife, Frutarom Inc) to a low-calorie beverage increases feelings of satiety and decreases hunger and lunchtime food intake. A lower dose of 4 grams appears to be less effective for reducing hunger but was considered to be more palatable (18350).
• Parkinson disease. It is unclear if oral fenugreek seed is beneficial for Parkinson disease symptoms. Details: One small clinical study in patients with Parkinson disease who are also using levodopa shows that taking fenugreek seed extract (Indus Biotech Private Limited, Pune) 300 mg twice daily for 6 months does not seem to improve behavioral or motor symptoms when compared with placebo (90113).
• Peptic ulcers. Although there is interest in using oral fenugreek for peptic ulcers, there is insufficient reliable information about the clinical effects of fenugreek for this condition.
• Polycystic ovary syndrome (PCOS). It is unclear if oral fenugreek seed is beneficial for PCOS. Details: A small clinical study in adults with symptomatic PCOS shows that adding a specific fenugreek seed extract (Goldarou Pharmaceutical Co.) 500 mg twice daily to metformin for 8 weeks does not improve insulin resistance, insulin sensitivity, or other symptoms when compared with placebo and metformin (90117). However, other small clinical studies in adults with PCOS show that taking another specific fenugreek seed extract (Furocyst, Cepham Inc.) 1000 mg, enriched with 40% furostanolic saponins, daily for 90 days is associated with a reduction in ovarian cyst size in 46% of patients, complete dissolution in 36% of patients, normalization of menstrual cycles in 71% to 80% of patients, and subsequent pregnancy in 12% of patients. Further, this extract appears to reduce mean cyst size by 42% to 45%, the number of cysts by 38%, ovary volume by 24% to 40%, and hirsutism by 27% while reducing luteinizing hormone, follicle-stimulating hormone, free testosterone, and prolactin and improving liver function and the severity of PCOS-associated ailments including insulin resistance and dyslipidemia (93422,112112,113502). The validity of some of these findings is limited by the lack of a comparator group. Furthermore, this study was funded by the supplement manufacturer.
• Vaginitis. There is limited evidence on the topical use of fenugreek cream in patients with atrophic vaginitis. Details: One small clinical study in postmenopausal patients with atrophic vaginitis shows that administration of 0.5 grams of fenugreek 5% cream intravaginally twice weekly for 12 weeks reduces symptoms of atrophic vaginitis and reduces vaginal pH when compared to baseline. However, fenugreek was not as effective as vaginal cream containing conjugated estrogens (103286). Another small clinical study in postmenopausal patients with vaginal atrophy shows that applying a fenugreek cream 5% intravaginally daily for 8 weeks seems to reduce dyspareunia and vaginal dryness and increase vaginal maturation when compared with a placebo cream (105023).
• Wound healing. Although there is interest in using topical fenugreek for wound healing, there is insufficient reliable information about the clinical effects of fenugreek for this purpose. More evidence is needed to rate fenugreek for these uses.

(Read more about FENUGREEK)

POSSIBLY EFFECTIVE

• Atopic dermatitis (eczema). Some clinical research suggests that topical licorice seems to improve symptoms of atopic dermatitis. Details: Applying gel formulations containing 1% or 2% licorice root extract three times daily for 2 weeks seems to reduce erythema by 35% to 61%, edema by 57% to 84%, and itching by 44% to 73%. The 2% gel seems to be more effective than the 1% gel (59732).
• Canker sores. Some clinical research suggests that topical licorice patches and mouth rinses seems to reduce ulcer size and pain in patients with recurrent aphthous stomatitis. Details: Clinical research shows that applying an oral patch containing licorice 0.015-0.229 mg/kg for 16 hours each day for 8 days does not affect ulcer healing time, but reduces ulcer size and post-stimulus pain, when compared with placebo (59769). A small clinical study also shows that applying bioadhesive hydrogel patches containing 1% licorice extract reduces the pain, as well as the diameter of necrosis and inflammatory halo of recurrent canker sores, when compared to baseline (59781). Mouth rinses containing licorice have also been used. One clinical study shows that swishing a diphenhydramine and 5% licorice extract solution around the mouth for about 3 minutes four times daily until the sores have healed reduces the average time to healing by 1.5 days when compared to a solution containing diphenhydramine alone. Pain was reduced by up to 69% more in those using licorice extract (104564). Another small clinical study shows that gargling with licorice extract four times daily for 2 days has a large beneficial effect on pain and ulcer size when compared with using a placebo gargle. The licorice extract was made by boiling licorice root 40 grams in one liter of water for 30 minutes and cooled (110319). In addition, preliminary clinical research shows that gargling with warm water containing deglycyrrhizinated licorice powder 200 mg four times daily for 7 days improves pain in 75% of patients by day one and results in complete healing in 75% of patients by day three (59857).
• Endotracheal intubation-related adverse effects. Some clinical research suggests that using licorice as a gargle or lozenge prior to endotracheal intubation can reduce adverse effects like sore throat and cough. Details: A meta-analysis of 5 clinical trials in patients undergoing elective surgical procedures shows that topical use of licorice, either as a gargle or lozenge, prior to endotracheal intubation reduces the risk for sore throat by 56% and reduces the risk for cough by 39% when compared with a control group at 24 hours post-extubation (100985). One clinical study included in this analysis shows that sucking on a single lozenge (Sualin, Hamdard Pharma) containing licorice extract 97 mg beginning 30 minutes prior to intubation reduces the risk for cough immediately after extubation by 56% when compared with a sugar candy lozenge. However, it doesn't seem to reduce cough at 30 minutes, 12 hours, or 24 hours post-extubation. This lozenge also appears to reduce the risk for sore throat by about 32% at 12 and 24 hours post-extubation, but not immediately or 30 minutes after extubation (25670). Additional clinical studies included in the meta-analysis show that gargling with fluid prepared with licorice 0.5 grams for at least one minute beginning 5 minutes prior to endotracheal intubation reduces the incidence and severity of post-extubation sore throat and coughing when compared with a water control (26464,59793).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Topical licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with mild to moderate acne associated with mask wearing shows that topical application of a combination of licorice root extract 0.3%, calendula 4%, and snail secretion filtrate 40% (AI complex) to the face twice daily for 12 weeks modestly reduces inflammatory, but not non-inflammatory or total, acne lesions when compared with placebo. There was no difference in overall treatment success, defined as at least almost clear skin or a large improvement (110322). It is unclear if any benefits are due to licorice, other ingredients, or the combination.
• Addison disease. Although there has been interest in using oral licorice for Addison disease, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Adrenal insufficiency. Although there has been interest in using oral licorice for adrenal insufficiency, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Allergic rhinitis (hay fever). It is unclear if using a licorice-containing nasal irrigation suspension improves symptoms in patients with allergic rhinitis. Details: A clinical study in patients with allergic rhinitis shows that using a nasal irrigation suspension containing licorice extract 900 mg daily for 1 month improves symptoms such as nasal blockage, rhinorrhea, sneezing, postnasal discharge, and olfactory disturbance when compared with baseline (108569). Although the study also utilized mometasone 2 mg nasal spray and isotonic saline nasal irrigation as comparators, symptom improvement was observed in all three groups, and there was no statistical comparison of outcomes between groups.
• Antipsychotic-induced hyperprolactinemia. Oral licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in females with risperidone-induced hyperprolactinemia shows that taking a combination of licorice and peony (Peony-Glycyrrhiza Decoction; PGD) 45 grams daily for 4 weeks reduces prolactin levels to a similar extent as bromocriptine (59775). However, another study shows that taking the same product at the same dose for 16 weeks has no effect on prolactin levels in females with antipsychotic-induced hyperprolactinemia when compared with placebo. Although the prolactin-related adverse event questionnaire total score was moderately improved, there was no effect on clinically meaningful symptoms or menstrual resumption (97219). Both studies show no effect on psychotic symptoms (59775,97219). Preliminary clinical research in male patients with antipsychotic-induced hyperprolactinemia shows that taking an herbal extract containing licorice and peony (shakuyaku-kanzo-to) 2.5 grams three times daily reduces prolactin levels after 4 weeks, but does not have a significant effect on prolactin levels 4 weeks after treatment cessation (59907).
• Asthma. Oral licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study conducted in Iran in children and adolescents aged 6-18 years old with mild-to-moderate asthma shows that taking a combination of licorice, sweet violet, and jalap (Anti-Asthma, Sinafaravar) twice daily for a month in addition to standard therapy reduces cough severity but does not change shortness of breath frequency or severity, rescue inhaler use, respiratory indices, or perceptions of asthma severity when compared with placebo (113569). It is unclear whether this effect is due to licorice, other ingredients, or the combination.
• Bleeding. Topical licorice might reduce bleeding when used in combination with other ingredients; its effect when used alone is unclear. Details: Some preliminary clinical research shows that topically applying 4 mL of a specific product (Ankaferd Blood Stopper, Mefar Ilaç Sanayi A.S.) containing licorice, Alpinia, thyme, stinging nettle, and common grape vine reduces bleeding, but does not improve the surgical time for episiotomy repair, when compared with saline (31010). Other preliminary clinical research shows that ampules of this same product placed in empty alveolus for up to 20 minutes reduces bleeding in postsurgical dental patients with increased bleeding tendency (31002).
• Cancer-related pain. It is unclear if oral licorice is beneficial for pain in patients with cancer. Details: Preliminary clinical research shows that taking a 1:1 combination of licorice root and peony root, along with a Taiwanese tonic vegetable soup comprised of lily bulb, lotus seed, and jujube fruit, reduces pain levels in terminal cancer patients when compared with patients consuming only the soup or the regular hospital diet (59770).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral licorice for CFS, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Colic. Although there has been interest in using oral licorice for colic, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Coronavirus disease 2019 (COVID-19). It is unclear whether oral licorice is beneficial for COVID-19. Details: A small open-label study in adults in Iran with moderate COVID-19 shows that taking licorice (D-Reglis, Irandarouk Pharmaceutical Company) 760 mg three times daily for 7 days in addition to standard treatment with hydroxychloroquine 200 mg twice daily for 7 days does not improve oxygen saturation, temperature, respiratory rate, clinical symptoms, length of hospital stay, or mortality, when compared with standard treatment alone (113633). As part of a combination treatment, a small clinical study in patients hospitalized in Egypt with moderate COVID-19 shows that administering oral licorice extract 300 mg (standardized to contain glycyrrhizin 60 mg) once daily and Boswellia serrata extract 300 mg twice daily for 14 days, along with following an institution-based COVID-19 treatment protocol, may modestly improve mortality and time to recovery when compared with patients receiving the standard protocol alone. The standard treatment protocol included acetaminophen, azithromycin, vitamin C, zinc, and enoxaparin (108579). It is unclear if any effect is due to licorice, Boswellia serrata, or the combination.
• Dental caries. It is unclear if oral licorice is beneficial for the prevention of dental caries. Details: One clinical study in adults shows that swishing 15 mL of a solution containing licorice extract 1% once nightly before bed for 5 days may reduce the acid production of cavity-causing bacteria, which may modestly reduce cavity risk, when compared with using a saline solution (108567). The validity of this study is limited by the short duration of treatment and follow-up.
• Dental plaque. It is unclear if licorice toothpaste or mouthwash is beneficial for reducing plaque. Details: Preliminary clinical research shows that using 0.25% or 0.50% glycyrrhizin-containing toothpaste twice daily does not reduce the amount of plaque, gingivitis, or bleeding in patients with proper dental hygienic measures when compared with the same toothpaste without glycyrrhizin (59812). Also, other preliminary clinical research shows that using glycyrrhizin-containing mouthwash for 3 days does not significantly reduce plaque levels (59855).
• Depression. It is unclear if adding oral licorice to standard treatment is beneficial for improving depression. Details: A very small, nonblinded clinical study in hospitalized adults with major depressive disorder shows that adding licorice extract 1400 mg daily, standardized to glycyrrhizin 7% to 8%, to standard treatment for 2 weeks improves depression rating scores when compared with baseline, although these improvements were numerically similar to those seen with standard treatment alone. Patients in the treatment group also took oral magnesium citrate 300 mg daily to prevent magnesium depletion. The validity of this finding is limited due to the small size of the study, short duration of treatment, and unclear reporting (108575).
• Diabetes. Although there has been interest in using oral licorice for diabetes, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Dry mouth. It is unclear if rinsing the mouth with licorice is beneficial for dry mouth in people on hemodialysis. Details: Preliminary clinical research in hemodialysis patients with dry mouth shows that rinsing with a licorice mouthwash containing 8.34 grams of licorice concentrate per 500 mL of water with every meal for 10 days does not affect salivary flow rate, but reduces subjective feelings of dry mouth by about 28%, when compared with a water-based mouthwash and control group (97220).
• Dysmenorrhea. It is unclear if oral licorice is beneficial for reducing pain. Details: Preliminary clinical research shows that taking a syrup providing licorice extract 750 mg twice daily for the first 5 days of the menstrual cycle reduces pain as effectively as ibuprofen 400 mg every 8 hours in patients with moderate or severe dysmenorrhea (104558).
• Dyspepsia. Oral licorice might improve symptoms of dyspepsia when used in combination with other ingredients; its effect when used alone is unclear. Details: Various combination products manufactured by Steigerwald Arzneimittelwerk GmbH have been evaluated for dyspepsia. Two specific combination products containing licorice root (Iberogast; STW-5-S) seem to improve symptoms of dyspepsia. The combinations include licorice plus milk thistle, peppermint leaf, German chamomile, caraway, celandine, angelica, and lemon balm either with (Iberogast) or without clown's mustard plant (STW-5-S) 1 mL three times daily for 4 weeks (19532). A meta-analysis of studies using the Iberogast product shows that taking 1 mL orally three times daily over a period of 4 weeks reduces severity of acid reflux, epigastric pain, cramping, nausea, and vomiting when compared with placebo (13089). Also, using a preparation containing clown's mustard plant, German chamomile, peppermint, caraway, licorice, and lemon balm (STW 5-II) 1 mL three times daily for up to 12 weeks improves dyspepsia symptoms in 40% more patients when compared with placebo (12724).
• Familial Mediterranean fever. It is unclear if oral licorice is beneficial for familial Mediterranean fever. Details: Preliminary clinical research shows that taking a combination of licorice, andrographis, Siberian ginseng, and schisandra (ImmunoGuard, Inspired Nutritionals) four tablets three times daily for one month reduces the duration, frequency, and severity of attacks of familial Mediterranean fever in children when compared with placebo (12382). It is unclear if these effects are due to licorice, other ingredients, or the combination.
• Helicobacter pylori. It is unclear if oral licorice is beneficial for Helicobacter pylori eradication. Details: Some preliminary clinical research shows that adding licorice (D-Reglis, Iran Darouk Pharmaceutical Co.) 380 mg twice daily to conventional clarithromycin-based triple therapy for 14 days improves eradication rate by an additional 21% when compared with conventional treatment alone. However, any additional benefit might be limited to patients with peptic ulcer disease (97221). Other preliminary clinical research shows that taking a combination of licorice extract 100 mg and Lactobacillus paracasei HP7 in 150 mL of fermented milk daily for 8 weeks does not increase eradication rates when compared with fermented milk alone, although it may improve gastrointestinal symptom scores, decrease the gastric load of Helicobacter pylori, and improve some measures of inflammation when compared to baseline (100984).
• Hepatitis. Evidence for the use of intravenous licorice in the management of hepatitis B and C is mixed. Details: In some preliminary clinical research, a specific glycyrrhizin-containing intravenous preparation (Stronger Neominophagen C, Minophagen Pharmaceutical Co. Ltd.) appears to reduce mortality due to viral hepatitis by about 50% (3250). Other clinical research suggests that this same product reduces serum alanine aminotransferase (ALT) in hepatitis C patients but does not improve hepatitis C virus (HCV)-RNA levels (3247,59712,59721,59920). When used long-term, this preparation seems to reduce the risk of hepatocellular carcinoma in hepatitis C patients when compared to long-term use of other supplements, such as vitamin K (59905). This product has been used in various doses: 40 or 100 mL, containing 2 mg glycyrrhizin, 1 mg cysteine, and 20 mg of glycine per mL of solution, administered daily for 4-8 weeks, followed by 40 or 100 mL 2-7 times weekly for 2-16 weeks, has been used (3250,59905,59915); 40-120 mL diluted in 100 mL of 5% glucose solution and administered three times weekly for 4 weeks (59712,59721); 100 mL, which contained 200 mg glycyrrhizin, administered undiluted six times weekly for 4 weeks (59721); or 60 mL administered three times weekly for 16 weeks (59920). Other research shows that this preparation reduces ALT, aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGT) in patients with hepatitis B virus (59915). Oral licorice has not been evaluated for this purpose.
• Hypercholesterolemia. It is unclear if oral licorice is beneficial for improving cholesterol. Details: Preliminary clinical research shows that taking licorice root extract 0.1 grams daily for one month reduces plasma total cholesterol levels by 5%, plasma low-density lipoprotein (LDL) cholesterol levels by 9%, and plasma triglyceride levels by 14% when compared with baseline in patients with moderate hypercholesterolemia (59725). The validity of these findings is limited by the lack of a comparator group.
• Hyperkalemia. It is unclear if oral licorice is beneficial for reducing potassium levels. Details: Some clinical research in adults with diabetes and hypoaldosteronism suggests that taking glycyrrhizin 150 mg daily decreases potassium levels when compared with calcium polystyrene sulfonate (59897). Also, one very small clinical study in patients with anuria shows that taking glycyrrhetinic acid 1 gram daily for 2 weeks seems to decrease plasma potassium, but does not improve blood pressure, when compared with placebo (59723).
• IgA vasculitis. Oral licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small retrospective study in patients aged 5-36 years with newly diagnosed IgA vasculitis shows that taking compound glycyrrhizin (Eisai Pharmaceutical Co, Ltd) three times daily along with loratadine, calcium, vitamin C, rutin, and other unspecified conventional treatments is associated with an improvement in cutaneous purpura symptoms and time to symptom regression when compared with placebo. After 1 month, the rate of complete resolution and time to regression in the treatment group was 82% and 5 days, respectively, compared with 65% and 8 days, respectively, in the placebo group. Compound glycyrrhizin contained glycyrrhizin, glycine, and methionine and was dosed by age, with a dose of 25 mg daily in those 12 years or younger and 50 mg daily in those over 12 years (108580).
• Irritable bowel syndrome (IBS). Oral licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that a formulation containing licorice root, slippery elm bark, lactulose, and oat bran daily for 2 weeks improves stool consistency and increases bowel movement frequency by 20% in individuals with constipation-predominant IBS when compared to baseline. Symptoms of abdominal pain, bloating, straining, and global severity might also be reduced (35462). The validity of these findings is limited by the lack of a comparator group. Additionally, it is unclear if any benefits are due to licorice, other ingredients, or the combination.
• Lichen planus. It is unclear if intravenous licorice is beneficial for lichen planus. Details: A very small clinical study shows that intravenous administration of 0.2% glycyrrhizin solution, 40 mL daily for 4 weeks, improves clinical symptoms of oral lichen planus in a greater percentage of patients with chronic hepatitis C when compared with dental cleaning (59903). There is no evidence suggesting that oral licorice is beneficial.
• Liver cancer. Although there has been interest in using oral or intravenous licorice preparations for liver cancer, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Melasma. Topical licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that applying a topical cream (Clariderm Clear, Stiefel Laboratories Inc.) containing 7% licorice, emblica, and belides twice daily for 60 days is as effective as a cream containing 2% hydroquinone for lightening the skin in patients with melasma (59824). It is unclear if this effect is due to licorice, other ingredients, or the combination.
• Menopausal symptoms. It is unclear if oral licorice is beneficial for reducing hot flash frequency or severity. Details: In one preliminary clinical study, taking licorice root extract 330 mg orally three times daily for 8 weeks modestly reduces the frequency of hot flashes by about 1.3 per day and the severity of hot flashes by about 40% when compared with placebo (94659). However, another preliminary clinical study shows that taking a specific licorice root extract (D-Reglis, Iran Darouk Pharmaceutical Co.) 650 mg orally daily for 90 days does not reduce the number or severity of hot flashes when compared to baseline (25694).
• Muscle cramps. It is unclear if oral licorice is beneficial for muscle cramps due to cirrhosis or hemodialysis. Details: Preliminary clinical research shows that taking a specific combination of licorice and peony (shakuyaku-kanzo-to) might reduce muscle cramps in patients with hepatic cirrhosis or in patients undergoing hemodialysis when compared to baseline (13550,13551,13552). This combination was taken as 6-7.5 grams daily in up to three divided doses for 2-4 weeks in two studies (13550,13552). In a third study, the combination was taken as 2.5 grams during hemodialysis with self-administration at the onset of muscle cramping (13551).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral licorice is beneficial for NAFLD. Details: A small clinical trial in females with NAFLD shows that taking licorice extract (Shirin Darou Company, Shiraz, Iran) 500 mg twice daily for 12 weeks improves some measures of liver health and glycemic control when compared with placebo. Modest improvements occurred in levels of alanine aminotransferase, as well as in measures of insulin resistance and severity of liver steatosis based on ultrasonographic evaluation. There were no effects on body mass index (BMI), plasma lipids, fasting blood glucose, or other liver enzymes. All patients were also given weight loss and healthy lifestyle advice (110320). Preliminary clinical research shows that taking licorice root extract 2 grams daily for 2 months reduces liver function enzyme levels in patients with NAFLD when compared to pre-treatment (59841). It is unclear if this reduction is clinically significant.
• Obesity. It is unclear if oral licorice is beneficial for weight loss. Details: Preliminary clinical research shows that taking a specific licorice flavonoid oil (Glavonoid) 300 mg daily for 8 weeks has no effect on weight or body fat when compared with placebo in obese patients (17727).
• Oral mucositis. It is unclear if oral or topical licorice is beneficial for the prevention or treatment of chemotherapy- or radiation-induced oral mucositis. Details: In patients with head and neck cancer undergoing chemoradiation, preliminary clinical research shows that using oral and topical licorice powder twice daily in addition to conventional treatments for 6 weeks reduces the overall incidence of mucositis and also reduces the risk of developing severe oral mucositis to 15.5%, compared with 20% in those using topical honey and 43% in those using conventional treatments alone. Licorice treatment consisted of yastimadhu powder 5 grams mixed in honey for topical application in the mouth, as well as yastimadhu capsule 500 mg twice daily orally (104562). A small clinical trial in patients with head and neck cancer and oral mucositis currently undergoing radiation therapy shows that applying a mucoadhesive film containing licorice to the upper lip mucosal surface four times daily for 4 weeks, in conjunction with standard oral care, improves pain scores, mucositis grading, and ulcer size when compared with placebo film (108572). The validity of this finding is limited due to the short duration of treatment and exclusion of patients with severe mucositis.
• Osteoarthritis. Although there has been interest in using oral licorice for osteoarthritis, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Osteoporosis. Although there has been interest in using oral licorice for osteoporosis, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Parkinson disease. It is unclear if oral licorice is beneficial for improving Parkinson disease symptoms. Details: A small clinical study in patients with Parkinson disease shows that taking licorice extract 136 mg (containing glycyrrhizin 12.14 mg, polyphenols 136 mcg, and flavonoids 2.6 mcg) in a 5 mL syrup twice daily for 6 months improves Parkinson symptoms, tremor, and overall daily activities when compared with placebo (102961).
• Peptic ulcers. Evidence for the use of oral licorice for peptic ulcers is mixed. Details: There is some evidence that taking 6-12 tablets each containing deglycyrrhizinated licorice 380 mg, bismuth subnitrate 100 mg, aluminum hydroxide gel 100 mg, magnesium carbonate 200 mg, sodium bicarbonate 100 mg, and powdered alder buckthorn bark 30 mg (Caved-S, Cedona) in up to three divided doses daily for 4-16 weeks might accelerate the healing of peptic ulcers (11312,11313). Some clinical research also shows that this product is as effective as carbenoxolone sodium (Biogastrone) when taken at doses of two tablets three times daily after meals for 4 weeks (59871). In contrast, taking deglycyrrhizinated licorice (Ulcedal, Cedona, and others) 450-1000 mg three to five times daily for 4-8 weeks or glycyrrhizinic acid-reduced licorice 760 mg three times daily for 6 weeks does not seem to reduce the need for medication, pain, burning, or other discomfort in patients with peptic ulcers when compared with placebo (59864,59865,59873,59874).
• Physical performance. It is unclear if oral licorice is beneficial for improving physical performance in older females. Details: A small clinical trial in healthy females 59 years and older shows that taking licorice flavonoid oil 300 mg orally daily for 16 weeks in addition to strength training does not improve walking speed or other measures of functional mobility when compared with strength training alone (102960).
• Polycystic ovary syndrome (PCOS). Oral licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking licorice root extract 2250 mg daily along with Ceylon cinnamon, levant berry, St. John's Wort, peony, and tribulus for 3 months with lifestyle modification improves symptoms of PCOS, including a reduction in oligomenorrhea/amenorrhea by 33% and the number of days between menstrual cycles by 43 days when compared with lifestyle modification alone. Although conception rate increased 4-fold in the intervention group, live birth rate was similar between groups (97216). The effect of licorice alone for the treatment of PCOS is unknown.
• Prostate cancer. Although there has been interest in using oral licorice for prostate cancer, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Psoriasis. It is unclear if topical licorice is beneficial for improving psoriasis symptoms. Details: Preliminary clinical research shows that using a topical cream containing licorice extract and milk proteins twice daily for 4 weeks does not reduce the duration of corticosteroid cream therapy in patients with palmar and/or plantar psoriasis, but may improve skin peeling, the area of skin affected, and some subjective symptoms, when compared with corticosteroid cream alone (59823).
• Smoking cessation. Oral licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized clinical study in adults in India with a history of smoking 5 or more cigarettes daily for at least 3 years shows that taking a specific combination product containing licorice 200 mg, ashwagandha, cowhage, ginger, turmeric, and other herbal extracts (Smotect, Smotect India) twice daily for 3 months reduces the number of cigarettes smoked daily and levels of alveolar carbon monoxide and carboxyhemoglobin but does not improve lung capacity when compared with placebo (112115). It is unclear if these effects are due to licorice, other ingredients, or the combination.
• Systemic lupus erythematosus (SLE). Although there has been interest in using oral licorice for SLE, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Tuberculosis. Although there has been interest in using oral licorice for tuberculosis, there is insufficient reliable information about the clinical effects of licorice for this condition.
• Urticaria. Oral licorice has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of clinical research in adults with chronic urticaria shows that taking compound glycyrrhizin, containing glycyrrhizin, N-acetyl cysteine, and glycine, as 50-75 mg three times daily along with desloratadine 5-8.8 mg daily for 4 weeks improves response rate, cure rate, and recurrence rate when compared with desloratadine alone (108571). Another meta-analysis of clinical research in pediatric and adult patients with chronic urticaria shows that taking compound glycyrrhizin 25-75 mg 2-3 times daily improves efficacy rate of symptom reduction, increases cure rate, and decreases recurrence rate when compared with second-generation antihistamine monotherapy (113634). However, most studies included in the meta-analyses were low quality, and all studies were conducted in China. Higher quality studies in other geographic locations are needed to confirm these findings.
• Vitiligo. It is unclear if the licorice constituent compound glycyrrhizin is beneficial for vitiligo. Details: A meta-analysis of 14 clinical studies in patients aged 3-68 years old with vitiligo shows that taking licorice constituent compound glycyrrhizin 25-75 mg 3 times daily for 2-6 months with standard treatment improves effectiveness, cure rate, and immune-mediated inflammatory markers when compared with standard treatment alone (112232). Additionally, a meta-analysis of clinical studies conducted in China in adults with vitiligo suggests that taking oral or intramuscular compound glycyrrhizin for 10 weeks to 6 months in combination with conventional therapies, including phototherapy, immunosuppressants, or traditional Chinese medicine, increases the percentage of patients with more than 50% regimentation when compared with conventional treatments alone (113635). More evidence is needed to rate licorice for these uses.

(Read more about LICORICE)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Asthma. Although there is interest in using oral mullein for asthma, there is insufficient reliable information about the clinical effects of mullein for this condition.
• Bronchitis. Although there is interest in using oral mullein for bronchitis, there is insufficient reliable information about the clinical effects of mullein for this condition.
• Cough. Although there is interest in using oral mullein for cough, there is insufficient reliable information about the clinical effects of mullein for this purpose.
• Diarrhea. Although there is interest in using oral mullein for diarrhea, there is insufficient reliable information about the clinical effects of mullein for this purpose.
• Hemorrhoids. Although there is interest in using topical mullein for hemorrhoids, there is insufficient reliable information about the clinical effects of mullein for this purpose.
• Influenza. Although there is interest in using oral mullein for influenza, there is insufficient reliable information about the clinical effects of mullein for this condition.
• Migraine headache. Although there is interest in using oral mullein for migraine headache, there is insufficient reliable information about the clinical effects of mullein for this condition.
• Otitis media. Topical mullein has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that applying a specific combination product containing mullein, garlic, calendula, and St. John's wort in olive oil (Otikon Otic Solution, Healthy-On Ltd), five drops into the affected ear three times daily for 3 days, reduces ear pain in children and adolescents with otitis media (39500,39552). Whether this effect is due to mullein, one of the other ingredients, or the combination is unclear.
• Pneumonia. Although there is interest in using oral mullein for pneumonia, there is insufficient reliable information about the clinical effects of mullein for this condition.
• Wound healing. It is unclear if topical mullein is helpful for healing episiotomy wounds. Details: In preliminary clinical research in primiparous patients with episiotomy wounds, applying a cream containing mullein flower extract 7.5%, 2 cm twice daily for 10 days, improves redness, edema, ecchymoses, discharge, and wound edge adhesions (REEDA score for episiotomy wound healing) at 10 days, but not earlier, when compared with placebo (107873). More evidence is needed to rate mullein for these uses.

(Read more about MULLEIN)

EFFECTIVE

• Acetaminophen poisoning. Oral and intravenous N-acetyl cysteine, as prescription drug products, are effective for treating acetaminophen poisoning. Details: Administering prescription N-acetyl cysteine orally or intravenously is effective in decreasing mortality rate and preventing the permanent sequelae of acetaminophen poisoning (17,64513,64745,64746). N-acetyl cysteine injection and oral effervescent tablets are approved by the US FDA for this use (102147,104164).
• Atelectasis. When inhaled, N-acetyl cysteine is effective for treating atelectasis. Details: N-acetyl cysteine solution for inhalation is effective for atelectasis caused by mucus obstruction (15,91650) and is approved by the US FDA for this use (102147).
• Bronchial diagnostic studies. When inhaled, N-acetyl cysteine is effective for bronchial diagnostic study preparation. Details: N-acetyl cysteine solution for inhalation is helpful when used to prepare people for bronchial diagnostic studies (15,91650), and is approved by the US FDA for this use (102147).
• Tracheostomy care. When inhaled and used as adjunct therapy, N-acetyl cysteine is effective for preventing endotracheal crusting in patients with a tracheostomy. Details: N-acetyl cysteine solution for inhalation is effective when used as an adjunct for preventing endotracheal crusting in tracheostomy care (15), and is approved by the US FDA for this use (102147).

POSSIBLY EFFECTIVE

• Angina. Oral or intravenous N-acetyl cysteine may reduce nitroglycerin tolerance in patients with angina. However, some studies suggest that N-acetyl cysteine might increase the risk for severe headaches and hypotension when used with intravenous or transdermal nitroglycerin. Details: Administering N-acetyl cysteine orally or intravenously, in combination with nitroglycerin, seems to improve unstable angina pectoris (2245,2246). There is also some clinical research showing that concurrent intravenous or oral administration of N-acetyl cysteine reduces the development of nitroglycerin tolerance (832,2245,64546). However, other research shows that taking N-acetyl cysteine orally does not reduce the development of nitroglycerin tolerance in angina patients (2281,2282). Additionally, severe headache and hypotension can occur when oral N-acetyl cysteine and nitroglycerin are administered together, which may limit the feasibility of concomitant use (2245).
• Autism spectrum disorder. Oral N-acetyl cysteine may improve irritability, but not other symptoms, associated with autism spectrum disorder. Details: One small clinical study in children with autism shows that taking N-acetyl cysteine 900 mg daily for 4 weeks followed by 900 mg twice daily for 4 weeks and then 900 mg three times daily for 4 weeks improves symptoms of irritability when compared with placebo (91241). Another small clinical study in children and adolescents with autism shows that taking N-acetyl cysteine 1200 mg daily plus risperidone for 8 weeks is more effective than risperidone alone for reducing irritability (91239). However, it does not seem to improve other symptoms, such as hyperactivity, social withdrawal, lethargy, repetitive behaviors, and inappropriate speech (91239,91241,97047).
• Bronchitis. Via inhalation, N-acetyl cysteine is FDA-approved for managing acute episodes of bronchitis. Oral N-acetyl cysteine may help to reduce the occurrence of acute exacerbations of chronic bronchitis when used for 3-36 months. Details: N-acetyl cysteine solution for inhalation is FDA-approved for the management of acute bronchopulmonary disease, including bronchitis (102147). Taking N-acetyl cysteine 1200-1500 mg daily orally for 4 months seems to reduce shortness of breath and coughing, and improve lung capacity, in patients with sulfur mustard-induced bronchitis (64586,64614). Also, taking N-acetyl cysteine orally, usually 400-600 mg daily, seems to reduce the risk of acute exacerbations of chronic bronchitis by a moderate amount when used for 3-36 months (6176,64419,102660). Symptom improvement has been shown to occur in 61% of patients taking N-acetyl cysteine, compared with 34% of those taking placebo (102660). However, oral N-acetyl cysteine does not seem to have a beneficial effect on chronic bronchitis when administered for shorter durations (64685,64696,64737,64818).
• Chronic obstructive pulmonary disease (COPD). Taking N-acetyl cysteine orally seems to decrease the exacerbation rate and improve symptoms in patients with moderate to severe COPD, particularly those who are not taking inhaled corticosteroids. Also, taking N-acetyl cysteine along with standard therapy appears to improve recovery in patients hospitalized due to an acute exacerbation. Details: N-acetyl cysteine solution for inhalation is FDA-approved for the management of chronic bronchopulmonary disease, such as COPD (102147). A meta-analysis of 12 clinical studies involving 2,691 patients shows that N-acetyl cysteine, given as 257-1800 mg daily for at least 6 months, decreases the number of patients experiencing at least one COPD exacerbation by 15% when compared with placebo; however, it is not associated with a reduction in COPD exacerbation rate or improvement in measures of lung function (97046). Some smaller studies have shown a higher improvement rate of 23% to 40%, with the greatest efficacy seen in patients who are not already taking inhaled corticosteroids (10429,64552). While some studies have failed to show any benefit of N-acetyl cysteine, the lack of benefit appears to correlate with a treatment duration of less than 6 months (64704,97039,97046). The 2015 guidelines from the American College of Chest Physicians and Canadian Thoracic Society (AECOPD) recommend that N-acetyl cysteine be considered as an adjunctive treatment option for patients with moderate to severe COPD and a history of 2 or more exacerbations in the previous 2 years (97043). The 2017 Global Initiative for Chronic Obstructive Lung Disease (GOLD) guideline also states that N-acetyl cysteine may be an appropriate treatment option for patients who are not able to use inhaled corticosteroids (97050). In hospitalized patients with an acute exacerbation of COPD, preliminary clinical research shows that adding N-acetyl cysteine 1200 mg daily to regular treatment has a moderate effect on wheeze and the need for oxygen over a 7-day period when compared with regular treatment alone (102653).
• Contrast induced nephropathy. Oral or intravenous administration of N-acetyl cysteine seems to prevent contrast induced nephropathy in patients with kidney dysfunction. However, it is not beneficial in those with normal kidney function or diabetes. Details: Large meta-analyses of over 150 clinical studies in patients with reduced kidney function (serum creatinine of 1.2-2.4 mg/dL) show that oral N-acetyl cysteine is more effective than either sodium bicarbonate or saline hydration alone in preventing contrast agent-induced kidney damage after coronary angiography, computed tomography, left heart catheterization, and/or percutaneous coronary intervention. N-acetyl cysteine in combination with sodium bicarbonate appears to have similar efficacy to N-acetyl cysteine monotherapy, with an odds ratio of 0.62-0.67, when compared with hydration alone. Pretreatment with high-dose statin, prostaglandin, or theophylline appears to be more effective than N-acetyl cysteine, with odds ratios of 0.37, 0.37, and 0.48, respectively, when compared with hydration alone. However, combination treatment with N-acetyl cysteine and a high-dose statin appears to provide the greatest benefit of all treatments studied, with an odds ratio of 0.31, when compared with hydration alone. No treatments demonstrate significant efficacy in reducing the risk of contrast induced nephropathy in patients with diabetes (97036,97038). Some evidence also suggests that N-acetyl cysteine may have similar effects to fenoldopam in reducing the risk of contrast induced nephropathy in patients with reduced kidney function (64489,97036,97038). N-acetyl cysteine does not reduce the risk of contrast induced nephropathy in patients with normal kidney function (mean serum creatinine less than 1.2 mg/dL) when compared with control (64538,64573,64617). Although many individual studies have failed to show a significant benefit (11430,64514,64543,64561,64581,64623,64639,91232,91236,106884), pooled evidence from these and many additional studies provide a benchmark for the place for N-acetyl cysteine in reducing the risk of contrast induced kidney damage in people with reduced kidney function.
• Hyperhomocysteinemia. Oral N-acetyl cysteine seems to reduce homocysteine levels. Details: Taking N-acetyl cysteine orally seems to reduce homocysteine levels in patients with elevated homocysteine levels, including those with kidney failure requiring dialysis (2258,64542,64596).
• Hyperlipidemia. Oral N-acetyl cysteine seems to reduce lipoprotein(a) levels. Details: Taking N-acetyl cysteine orally seems to modestly reduce lipoprotein(a) levels in patients with hyperlipidemia (2256,2257,64516).
• Ifosfamide (Ifex) toxicity. Oral N-acetyl cysteine may be beneficial for reducing ifosfamide toxicity, although it does not appear to be as effective as mesna. Details: Taking N-acetyl cysteine orally seems to reduce ifosfamide-induced bladder toxicity (5808,10270,64730). However, mesna seems to be more effective for preventing ifosfamide toxicity than N-acetyl cysteine (10748).
• Influenza. Oral N-acetyl cysteine may reduce the risk for symptomatic influenza. Details: One multi-center clinical trial conducted in Italy shows that taking N-acetyl cysteine 600 mg twice daily for 6 months does not prevent influenza infection, but reduces the risk for clinically apparent disease by 68%, when compared with placebo (2260).
• Kidney failure. Oral N-acetyl cysteine may reduce the risk for cardiovascular events in patients with kidney failure. Details: One clinical study in adults with kidney failure who have been on dialysis for at least 3 months shows that taking N-acetyl cysteine 600 mg twice daily reduces the incidence of cardiovascular events, such as ischemic stroke and myocardial infarction, by about 40% when compared with placebo. There was no effect on total mortality or mortality from cardiovascular causes, although the study may have been inadequately powered to detect a difference in these outcomes (10430).
• Myocardial infarction (MI). Intravenous N-acetyl cysteine, along with standard therapy, seems to improve outcomes in patients with MI. Oral N-acetyl cysteine has not been evaluated for this use. Details: Clinical research in adults undergoing percutaneous coronary intervention (PCI) for ST-segment elevation MI shows that administering N-acetyl cysteine with nitroglycerin as a continuous intravenous infusion for 48 hours reduces myocardial infarct size by 5.5%, doubles the extent of myocardial salvage, and shortens the time to chest pain resolution when compared with nitroglycerin plus placebo (97044). Additional preliminary clinical research shows that intravenous N-acetyl cysteine, when given with nitroglycerin and streptokinase in patients with evolving MI, may preserve left ventricular function and reduce oxidative stress (7872,64502,64778).

POSSIBLY INEFFECTIVE

• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Subcutaneous administration of N-acetyl cysteine does not seem to improve survival or disease progression in patients with ALS. Details: One clinical trial in patients with ALS shows that administering N-acetyl cysteine 50 mg/kg daily for 12 months via subcutaneous injection does not improve survival or slow disease progression when compared with placebo (2254).
• Anthracycline cardiotoxicity. Oral N-acetyl cysteine does not seem to prevent or treat doxorubicin-induced cardiac toxicity. Details: Small clinical studies show that taking N-acetyl cysteine orally does not seem to prevent or reverse doxorubicin-induced cardiac toxicity when compared with placebo or a control group (2252,2253,64712).
• Bronchopulmonary dysplasia. Intratracheal N-acetyl cysteine does not seem to prevent bronchopulmonary dysplasia in premature infants. Details: Clinical research in premature infants shows that intratracheal N-acetyl cysteine does not seem to improve symptoms, hasten recovery of chronic lung disease, or reduce the risk of bronchopulmonary dysplasia when compared with placebo (64460,64490).
• Cannabis use disorder. Oral N-acetyl cysteine does not seem to improve abstinence rates in patients with cannabis use disorder. Details: Most clinical research in adolescents and adults with cannabis use disorder shows that taking N-acetyl cysteine 1200 mg twice daily for 8-12 weeks as an adjunct to counseling and other interventions does not reduce symptoms of depression or help with cannabis abstinence (99531,102663,102666,102668). Although a single study shows that taking N-acetyl cysteine more than doubles the odds of a negative urine cannabinoid test over an 8-week period in adolescents aged 15-21 when compared with placebo, there was no significant difference in the time to first negative urine cannabinoid test or end of treatment abstinence (102666).
• Cystic fibrosis. Oral or inhaled N-acetyl cysteine does not seem to improve lung function in patients with cystic fibrosis. Details: Most clinical research shows that taking oral or nebulized N-acetyl cysteine does not significantly improve lung function or lung capacity in patients with cystic fibrosis when compared with a control (22735,64406,64671,64743). However, one preliminary clinical study shows that high-dose oral N-acetyl cysteine reduces the number and activity of airway neutrophils in these patients when compared with placebo (64510).
• Erythropoietic protoporphyria (EPP). Oral N-acetyl cysteine does not seem to improve photosensitivity in patients with EPP. Details: Small clinical studies show that taking N-acetyl cysteine 1800 mg daily orally for 4 weeks does not improve photosensitivity in patients with EPP when compared with placebo or baseline (64448,64756).
• Helicobacter pylori. Adding oral N-acetyl cysteine to conventional Helicobacter pylori (H. pylori) eradication regimens does not seem to increase eradication rates. Details: Despite conflicting findings from individual, small clinical studies (64497,97042), meta-analyses of clinical research show that adding N-acetyl cysteine to a standard antibiotic eradication regimen does not improve eradication when compared with standard eradication therapy alone (99530,106901). N-acetyl cysteine has also been evaluated in combination with other ingredients. Preliminary clinical research shows that taking N-acetyl cysteine 600 mg orally twice daily in combination with curcumin 30 mg, bovine lactoferrin 100 mg, and pantoprazole 20 mg, all taken twice daily for one week, without antibiotic therapy does not eradicate H. pylori infection, although it might improve dyspeptic symptoms and gastrointestinal inflammation (64559).
• Hepatitis. Oral N-acetyl cysteine does not appear to improve treatment response in patients with hepatitis. However, when taken with interferon, it might lengthen the time to relapse. Details: Taking N-acetyl cysteine orally does not seem to benefit patients with acute viral hepatitis (64462). Also, adding N-acetyl cysteine to conventional interferon therapy does not seem to improve treatment response in patients with hepatitis C when compared with interferon therapy alone (64418,64799,64825). However, some clinical research shows that adding N-acetyl cysteine to interferon therapy delays relapse in hepatitis C patients when compared with interferon treatment alone (64424).
• HIV/AIDS. Oral N-acetyl cysteine does not seem to increase CD4+ cell count in patients with HIV. Details: Small clinical studies show that taking N-acetyl cysteine 400 mg orally twice daily or 600 mg once daily for 4-6 months does not improve CD4+ cell counts or viral load in patients with HIV when compared with placebo (64482,64779). In addition, taking N-acetyl cysteine 600 mg orally three times daily in combination with sodium selenite 500 mcg daily for up to 24 weeks does not affect the percentage of CD4+ lymphocytes or viral load in HIV patients when compared with a control (64798).
• Hypotension. Oral N-acetyl cysteine does not seem to improve renal outcomes in patients with prolonged hypotension. Details: One clinical trial in patients with prolonged hypotension shows that taking N-acetyl cysteine orally for 7 days does not reduce the risk of acute kidney failure when compared with placebo (64545).
• Infertility. Oral N-acetyl cysteine does not seem to improve fertility in females with unexplained infertility. Details: One clinical trial in females with unexplained infertility shows that taking oral N-acetyl cysteine 1200 mg daily in addition to clomiphene citrate 50 mg twice daily for 5 days, beginning on the second day of the cycle, does not improve pregnancy rate or reduce miscarriage rate when compared with clomiphene citrate alone (64528).
• Liver transplant. Intravenous N-acetyl cysteine during liver donor operation does not seem to improve liver transplant outcomes. Oral N-acetyl cysteine has not been evaluated for this use. Details: One clinical trial shows that administering N-acetyl cysteine intravenously during a liver donor operation and preserving the liver in cold solution containing N-acetyl cysteine does not reduce the risk of ischemia reperfusion injury or acute cellular rejection in liver transplant recipients when compared with control (64486).
• Pancreatitis. Oral N-acetyl cysteine does not seem to prevent pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP). Additionally, intravenous N-acetyl cysteine does not seem to reduce the risk of organ dysfunction in patients being treated for severe acute pancreatitis. Details: Two clinical trials show that taking oral N-acetyl cysteine 1200 mg once before undergoing ERCP does not reduce the risk of post-ERCP pancreatitis when compared with placebo (64522,109939). One of these trials also evaluated oral N-acetyl cysteine in combination with rectal indomethacin, but the incidence of post-ERCP pancreatitis did not appear to be lower when compared with taking indomethacin alone. However, the study may have been inadequately powered to detect a difference between those groups (109939). In patients with severe acute pancreatitis, intravenous N-acetyl cysteine, in combination with selenium and vitamin C, also does not seem to reduce the risk of organ dysfunction (64551).
• Postoperative recovery. Oral or intravenous N-acetyl cysteine does not seem to improve survival, prevent complications, or reduce length of hospital stay in patients undergoing cardiac or liver surgery. Details: N-acetyl cysteine, taken orally or intravenously, does not seem to reduce the risk of myocardial infarction, stroke, kidney injury, or mortality or reduce the length of hospital stay following cardiac surgery (64610,64624,64628,64635,91233,91240). While some meta-analyses of clinical research show that taking N-acetyl cysteine orally or intravenously reduces the odds of postoperative atrial fibrillation by 36% to 44% when compared with placebo in patients undergoing cardiac surgery (64635,91233,91240), conflicting results exist (64624). In patients undergoing liver resection, intravenous N-acetyl cysteine does not reduce complication rate, risk of liver failure, length of hospital stay, or mortality when compared with a control group. In fact, patients receiving N-acetyl cysteine were more likely to experience delirium and its associated complications (99532).

LIKELY INEFFECTIVE

• Head and neck cancer. Oral N-acetyl cysteine does not seem to reduce mortality, improve event-free survival, or prevent additional tumors in patients with head and neck cancer. Details: Taking N-acetyl cysteine orally does not prevent second primary tumors in patients with head and neck cancer (1710). Also, N-acetyl cysteine alone, or in combination with retinyl palmitate, has no effect on mortality or event-free survival in these patients (1710).
• Lung cancer. Oral N-acetyl cysteine does not seem to reduce mortality, improve event-free survival, or prevent additional tumors in patients with lung cancer. Details: Taking N-acetyl cysteine orally does not prevent second primary tumors in patients with lung cancer (1710). Also, N-acetyl cysteine alone, or in combination with retinyl palmitate, has no effect on mortality or event-free survival in these patients (1705,1710).
• Multisystem organ failure. Administering intravenous N-acetyl cysteine might increase the risk of mortality due to multisystem organ failure. Oral N-acetyl cysteine has not been evaluated for this use. Details: Administering N-acetyl cysteine intravenously, greater than 24 hours after hospital admission, might increase mortality rate due to multisystem organ failure. The effect of N-acetyl cysteine given within 24 hours of hospital admission requires further study (7871).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acute respiratory distress syndrome (ARDS). Research on the use of intravenous N-acetyl cysteine in patients with ARDS is conflicting. Oral N-acetyl cysteine has not been evaluated for this purpose. Details: Some clinical research shows that N-acetyl cysteine might reduce mortality and improve oxygenation in patients with acute lung injury/ARDS when compared with a control (64619). These patients were administered intravenous N-acetyl cysteine 150 mg/kg on the first day followed by 50 mg/kg for 3 more days. However, other clinical research shows that administering intravenous N-acetyl cysteine 40 mg/kg daily for 3 days does not reduce the risk of ARDS development in patients with acute lung injury (64771). Also, some clinical research shows that intravenous N-acetyl cysteine for up to 6 days does not reduce the time for improvement in patients with ARDS (64492). These discrepancies may be due to variations in genes involved in glutathione-S-transferase (GST) expression (64619).
• Adrenoleukodystrophy (ALD). It is unclear if oral or intravenous N-acetyl cysteine is beneficial in patients with ALD. Details: A case series of three male children with this rare condition suggests that administering N-acetyl cysteine orally and intravenously might improve overall survival and stabilize neurologic status after hematopoietic stem cell transplantation when compared with historical controls (64547).
• Aging. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in older adults shows that taking a combination product containing N-acetyl cysteine 100 mg/kg, glycerine 100 mg/kg, and alanine 200 mg/kg orally daily for 16 weeks modestly improved waist circumference, systolic blood pressure, and some serum markers of oxidative stress, but not body-mass index or diastolic blood pressure, when compared with placebo (110624). It is unclear if this effect is due to N-acetyl cysteine, other ingredients, or the combination.
• Alcohol-related liver disease. Although there has been interest in using oral N-acetyl cysteine for preventing alcohol-related liver damage, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Allergic rhinitis (hay fever). Although there has been interest in using oral N-acetyl cysteine for allergic rhinitis, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this condition.
• Altitude sickness. It is unclear if oral N-acetyl cysteine can treat or prevent altitude sickness. Details: One very small clinical trial shows that taking N-acetyl cysteine 400 mg daily does not reduce altitude-associated anorexia or improve food intake in individuals exposed to high altitudes when compared with either placebo or vitamin E 400 mg daily (64599).
• Alzheimer disease. It is unclear if oral N-acetyl cysteine is beneficial for Alzheimer disease. Details: One clinical trial in a small number of patients with Alzheimer disease shows that taking N-acetyl cysteine 50 mg/kg daily for 6 months does not improve most cognitive symptoms of Alzheimer disease when compared with placebo (7870). However, preliminary clinical research in adults with mild to moderate Alzheimer disease also shows that taking a combination product containing N-acetyl cysteine 2.55 grams, L-serine 12.35 grams, nicotinamide riboside 1 gram, and L-carnitine tartrate 3.73 grams orally once daily for 28 days followed by twice daily for 56 more days improves cognitive functioning scores by 14% to 29% when compared with placebo (110623). It is unclear if this effect is due to N-acetyl cysteine, other ingredients, or the combination.
• Aminoglycoside ototoxicity. Small clinical studies suggest that oral N-acetyl cysteine may modestly reduce the risk of ototoxicity caused by aminoglycoside therapy. Details: A meta-analysis of available clinical research in adults with kidney failure receiving aminoglycosides for bloodstream infections shows that taking N-acetyl cysteine 600 mg twice daily for a total of 14 days, or for up to 7 days after completion of aminoglycoside therapy, reduces the risk of hearing loss by 33% when compared with placebo. The findings of this analysis are limited by the small sample sizes and high risk of bias of the included studies (97049).
• Asthma. It is unclear if inhaling N-acetyl cysteine is beneficial in patients with asthma. Details: Preliminary clinical research shows that, when administered as an aerosol daily for one week in combination with isoproterenol, N-acetyl cysteine 10% improves lung capacity and decreases sputum viscosity when compared with placebo in patients with asthma (64674).
• Athletic performance. It is unclear if oral N-acetyl cysteine can improve athletic performance. Details: Some small clinical studies shows that N-acetyl cysteine might be beneficial if taken orally at a dose of 1200 mg daily for 9 days leading up to exercise or when administered intravenously both before and during exercise (64529,91248), but that it might not improve performance when taken as a single 20 mg/kg oral dose 60 minutes prior to exercise (102028).
• Biliary disorders. It is unclear if intravenous N-acetyl cysteine is beneficial in patients with biliary disorders. Oral N-acetyl cysteine has not been evaluated for this use. Details: Preliminary clinical research in patients undergoing surgical bypass for obstructive jaundice shows that postoperative intravenous N-acetyl cysteine for 48 hours reduces levels of some liver enzymes, but not bilirubin levels or mean hospital stay, when compared with a control group. Although all liver enzyme levels had not returned to normal by 30 days after surgery, they were more improved in the group using N-acetylcysteine (102654).
• Bipolar disorder. The effects of oral N-acetyl cysteine in patients with bipolar disorder are conflicting. Oral N-acetyl cysteine might reduce symptoms of depression and increase remission rates, but it does not appear to be beneficial for reducing symptoms of mania or for maintaining remission. Details: One clinical study in patients with bipolar disorder shows that taking N-acetyl cysteine 1000 mg twice daily as adjunct to usual therapy for 24 weeks reduces symptoms of depression when compared with placebo (64608). A subgroup analysis of patients from this study who were diagnosed with bipolar II disorder shows that this dose of N-acetyl cysteine can increase the number of patients who achieve remission of both depression and mania, but not the number achieving remission of only one of these, when compared with placebo (91243). However, other research shows that taking N-acetyl cysteine 3 grams daily in addition to standard therapy for 20 weeks does not improve depression when compared with placebo in patients with bipolar depression experiencing a depressive episode for at least 4 weeks. A limitation of this study is the high (56%) placebo response rate, which might have limited the ability to detect between-group differences in symptoms improvements (99529). Taking N-acetyl cysteine as an adjunct to usual therapy does not appear to be beneficial for maintaining remission. A clinical study in patients with bipolar disorder shows that, although taking N-acetyl cysteine 1000 mg twice daily for 8 weeks improves symptoms of bipolar disorder when compared to baseline, maintenance therapy with N-acetyl cysteine for an additional 6 months does not improve depression symptoms or prevent recurrence when compared with placebo (91234).
• Bronchiectasis. Oral N-acetyl cysteine has been evaluated in patients with bronchiectasis, with promising results. Details: Preliminary clinical research in Chinese adults with bronchiectasis shows that taking N-acetyl cysteine 600 mg twice daily for 12 months reduces the risk of exacerbation by 59% when compared with a control group receiving on-demand treatment only. For every eight patients treated with N-acetyl cysteine, one additional patient was free of exacerbations at 12 months when compared with on-demand treatment only (102027).
• Canker sores. It is unclear if rinsing the mouth with N-acetyl cysteine solution is beneficial in patients with canker sores. Details: Preliminary clinical research in patients with recurrent canker sores shows that rinsing the mouth with N-acetyl cysteine (ACC, HEXAL AG) 200 mg dissolved in water for 30 seconds is no more effective than 0.12% chlorhexidine digluconate for canker sore healing time or level of pain. However, pain was reduced by 50% to 90% more over baseline 2-4 days after use of N-acetyl cysteine when compared with 0.12% chlorhexidine digluconate (102659).
• Chemotherapy-induced hepatotoxicity. It is unclear if intravenous N-acetyl cysteine is beneficial in patients with chemotherapy-induced hepatotoxicity. Oral N-acetyl cysteine has not been evaluated for this use. Details: Some observational research in children aged 2-17 years with chemotherapy-induced hepatotoxicity has found that intravenous N-acetyl cysteine 3 mcg/kg over 24 hours is associated with day-to-day improvement in liver injury, based on liver function enzyme levels, when compared with no N-acetyl cysteine therapy. Decreases in liver enzymes also occurred earlier in patients using N-acetyl cysteine (102664).
• Chemotherapy-induced peripheral neuropathy. Small clinical studies suggest that oral N-acetyl cysteine may reduce the risk for peripheral neuropathy in patients receiving oxaliplatin. Details: One preliminary clinical study in patients with colon cancer shows that taking N-acetyl cysteine 1200 mg orally at 1.5 hours prior to oxaliplatin therapy reduces the incidence of oxaliplatin-induced neuropathy when compared with placebo (64505). Another small clinical trial in patients with gastric or colorectal cancers shows that taking N-acetyl cysteine (Osveh Pharmaceutical Company) 1200 mg one hour before receiving oxaliplatin during eight courses of chemotherapy reduces the incidence and severity of neurotoxicity symptoms when compared with placebo. In patients taking N-acetyl cysteine, 31% had no signs of neurotoxicity after oxaliplatin chemotherapy, compared with 0% of those taking placebo. Also, 44% had mild symptoms, compared with 6% of those taking placebo. However, there were no significant differences in electrophysiological sensory results (102665).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral N-acetyl cysteine for CFS, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Chronic kidney disease (CKD). Oral N-acetyl cysteine does not seem to improve kidney function in patients with CKD or reduce the risk of kidney injury or other complications after cardiac surgery in patients with CKD. However, intravenous N-acetyl cysteine might offer some benefit in patients with CKD undergoing cardiac surgery. Details: Clinical research shows that taking N-acetyl cysteine 1200 mg orally daily in combination with standard antihypertensive drugs does not reduce proteinuria or other markers of kidney injury in patients with CKD (64627). N-acetyl cysteine has also been evaluated for the prevention of acute kidney injury following cardiac surgery in patients with CKD, with conflicting results. Several meta-analyses have shown that N-acetyl cysteine does not reduce the incidence of acute kidney injury, postoperative complications, postoperative interventions, length of hospitalization, or mortality after cardiac surgery in adults with CKD (95766,95767,95768). However, these meta-analyses found that intravenous, but not oral, N-acetyl cysteine might be beneficial (95767,95768). A more recent meta-analysis shows that intravenous N-acetyl cysteine reduces the risk of postoperative acute kidney injury by 23% and reduces the risk of cardiac adverse events by 17% (99533). However, most of the studies included in this latter meta-analysis were small and the definition of cardiac events varied among the included studies. Higher quality research is needed to determine the benefit, if any, of N-acetyl cysteine in reducing acute kidney injury after cardiac surgery in patients with CKD.
• Cocaine dependence. It is unclear if oral N-acetyl cysteine is effective for reducing cravings or withdrawal symptoms in people trying to stop cocaine use. Details: Some preliminary clinical research shows that taking N-acetyl cysteine 600 mg twice daily for 2 days reduces the desire to use cocaine when compared with placebo in individuals with cocaine dependence (64563). However, other preliminary clinical research shows that taking oral N-acetyl cysteine 600 mg twice daily for 2 days does not reduce cravings or withdrawal symptoms when compared with placebo in patients hospitalized for cocaine dependency (64504).
• Colorectal cancer. It is unclear if oral N-acetyl cysteine is effective for preventing colorectal cancer. Details: Clinical research in a small group of patients with a history of adenomatous colonic polyps shows that taking N-acetyl cysteine 800 mg daily for 12 weeks reduces the proliferative index of colonic crypts, suggesting that N-acetyl cysteine might decrease the likelihood of colorectal cancer (7873).
• Coronary artery bypass graft (CABG) surgery. It is unclear if oral or intravenous N-acetyl cysteine is beneficial in patients undergoing CABG surgery. Details: A small clinical study shows that taking N-acetyl cysteine 300 mg orally in addition to intermittent blood cardioplegia does not affect postoperative outcomes or the risk of mortality when compared with control in patients undergoing elective CABG surgery (64638). Another small clinical study shows that giving N-acetyl cysteine 100 mg/kg by intravenous infusion, for two doses during CABG surgery and one postoperative dose, seems to reduce serum creatinine levels at 4 and 48 hours after surgery and reduce the incidence of acute kidney injury when compared with placebo. However, serum creatinine levels were within the normal range in all patients (106886).
• Coronavirus disease 2019 (COVID-19). Small clinical trials suggest that intravenous N-acetyl cysteine is not beneficial in patients at risk for respiratory failure from severe COVID-19. It is unclear if oral use is beneficial. Details: A small single-center clinical trial of patients presenting to the emergency room with COVID-19 pneumonia in Brazil shows that receiving intravenous N-acetyl cysteine 21 grams in dextrose 5% over 20 hours in conjunction with institutional standard care, including empiric antibiotics, does not reduce the need for mechanical ventilation, length of intensive care unit (ICU) stay, or mortality when compared with dextrose 5% (105560). Another small single-center clinical trial in patients with COVID-19 and acute respiratory distress syndrome (ARDS) in Iran shows that receiving a continuous intravenous infusion of N-acetyl cysteine 40 mg/kg in dextrose 5% daily for 3 days in conjunction with institutional standard care, including corticosteroids, vitamin C, vitamin D, and zinc, also does not reduce the need for mechanical ventilation, length of ICU stay, or mortality when compared with dextrose 5% (105561). Similarly, a retrospective study of patients hospitalized in Italy for COVID-19 pneumonia shows that receiving intravenous N-acetyl cysteine 300 mg three times daily, switched to 600 mg twice daily if the patient was clinically stable, for a duration of least 5 days, does not improve inpatient mortality, ICU admission, length of ICU stay, or the incidence of atelectasis, when compared with no supplementation. At a 6-month follow-up, treatment with N-acetyl cysteine also did not appear to impact long-term outcomes in these patients (108449). In contrast, a small, retrospective study in hospitalized patients with moderate to severe COVID-19 pneumonia shows that taking oral N-acetyl cysteine, 600 mg twice daily for 10 days in addition to standard care, including empiric antibiotics, corticosteroids, and remdesivir, reduces the risk for severe respiratory failure requiring ventilator support and reduces mortality at 14 days in those with severe pneumonia when compared with standard care alone (106885). Prospective, randomized, double-blind trials are needed to confirm these findings.
• Dental plaque. It is unclear if mouthwash solutions containing N-acetyl cysteine can reduce dental plaque; higher concentrations may be more effective than lower concentrations. Details: Preliminary clinical research shows that using a mouthwash solution containing N-acetyl cysteine 10% four times daily for 7 days reduces dental plaque (64687). However, other clinical research shows that rinsing twice daily for 3 weeks with N-acetyl cysteine 1.25% does not reduce the development of plaque. In addition, N-acetyl cysteine 1.25% was not beneficial when used for 2 weeks as a treatment for experimental plaque (102662).
• Dry eye. Small clinical studies suggest that eye drops containing N-acetyl cysteine, with or without chitosan, might improve objective measures of dry eye. Details: Preliminary clinical research in patients with dry eye shows that using tear solution containing 20% N-acetyl cysteine every two hours for 2 months improves objective, but not subjective, symptoms of dry eye syndrome when compared with artificial tears (64705). A small clinical study in patients with moderate to severe dry eye disease shows that applying a specific product (Lacrimera) containing chitosan-N-acetyl cysteine as one drop once or twice daily improves tear film thickness (TFT) after 10 minutes of application, and is maintained for 24 hours, when compared with placebo. Once or twice daily application does not seem to alter the level of benefit (97710). It is unclear if the benefit of this combination product is due to N-acetyl cysteine, chitosan, or the combination.
• Endometriosis. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with endometriosis-associated pelvic pain shows that taking a combination product containing N-acetyl cysteine 1200 mg, alpha lipoic acid 400 mg, bromelain 50 mg, and zinc 20 mg daily for 6 months improves pain and reduces analgesic intake when compared to baseline (99535). This study was limited by a lack of comparator group.
• Esophagogastroduodenoscopy (EGD). It is unclear if N-acetyl cysteine (NAC) can improve visualization when used as a premedication for EGD. Details: Clinical research shows that giving NAC orally, 600 mg in 90 mL of an emulsion formulation, 20 minutes prior to EGD reduces foaming and mucus, allowing better visualization of the mucosa. The percentage of patients with no bubbles affecting visualization is about 51% with NAC, compared with 34% with placebo. The percentage not requiring suction or endoscopic flushes is 50% with NAC and 27% with placebo. Giving simethicone 150 mg in combination with NAC further improves visualization (108941).
• Exercise-induced muscle damage. It is unclear if oral N-acetyl cysteine is effective for preventing or treating exercise-induced muscle damage. Details: One small clinical study shows that taking N-acetyl cysteine 20 mg/kg daily in three divided doses after muscle-damaging exercise does not improve muscle repair or inflammatory response in healthy patients taking part in a specific resistance training program (91244).
• Fibrocystic breast disease. It is unclear if oral N-acetyl cysteine is effective for fibrocystic beast disease. Details: Preliminary clinical research in adult females with fibrocystic breast disease and cyclical mastalgia shows that taking N-acetyl cysteine (Osvah Pharmaceutical Company) 600 mg orally once daily for 12 weeks modestly improves pain scores when compared with placebo (109938).
• Gingivitis. It is unclear if mouthwash containing N-acetyl cysteine is effective for the prevention or treatment of gingivitis. Details: Clinical research shows that rinsing twice daily for 3 weeks with N-acetyl cysteine 1.25% is slightly more effective than placebo for reducing the development of gingivitis. However, there was no effect on plaque. In addition, N-acetyl cysteine is not as effective as chlorhexidine 0.2% and had no benefit when used for 2 weeks as a treatment for experimental gingivitis (102662).
• Hangover. Although there has been interest in using oral N-acetyl cysteine for treating hangovers, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Hearing loss. It is unclear if oral N-acetyl cysteine is effective for preventing or treating hearing loss. Details: A meta-analysis of clinical trials in adults shows that taking N-acetyl cysteine 900-2700 mg orally daily for up to 42 days modestly protects against noise-induced hearing loss in middle to high hearing thresholds (0 to 4 kHz and 0 to 6 kHz), but not low hearing thresholds (0 to 2 kHz), when compared with control. However, the validity of this study is limited by high heterogeneity (109937). Another meta-analysis of 2 clinical trials in adults with sudden hearing loss shows that taking N-acetyl cysteine 1200 mg orally daily for 2 weeks to 3 months moderately improves pure tone threshold hearing when compared with control (109940).
• Hepatorenal syndrome. It is unclear if intravenous N-acetyl cysteine is beneficial in patients with hepatorenal syndrome. Oral N-acetyl cysteine has not been evaluated for this use. Details: A case series of 12 patients with hepatorenal syndrome reported that intravenous N-acetyl cysteine, starting with a 150 mg/kg loading dose over 2 hours, followed by a continuous infusion of 100 mg/kg daily for 5 days, modestly improved kidney function, but not liver function or blood pressure. When compared with historical controls, N-acetyl cysteine administration was also associated with an improvement in total survival time (1752). Prospective clinical studies are needed to confirm these findings.
• Hereditary hemorrhagic telangiectasia (HHT). It is unclear if oral N-acetyl cysteine is beneficial in patients with HHT. Details: One small clinical study shows that taking N-acetyl cysteine 600 mg three times daily orally for 12 weeks decreases the frequency and severity of daytime nosebleeds, but not nighttime nosebleeds, when compared to baseline in individuals with HHT (64643). The validity of these findings is limited by the lack of a comparator group.
• Idiopathic interstitial pneumonia. It is unclear if oral or inhaled N-acetyl cysteine is beneficial for the management of various forms of interstitial pneumonia. Details: A very small clinical study in patients with idiopathic interstitial pneumonia shows that taking N-acetyl cysteine 600 mg three times daily for 12 weeks seems to improve pulmonary function tests and decrease biochemical markers of disease when compared with baseline (7868). However, a meta-analysis of clinical research in patients with idiopathic pulmonary fibrosis, a specific type of interstitial pneumonia, shows that oral or inhaled N-acetyl cysteine does not reduce the risk of acute exacerbations or attenuate decline of lung function as measured by forced vital capacity (FVC), when compared with placebo (99538).
• Lead toxicity. Although there has been interest in using oral N-acetyl cysteine for lead toxicity, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Malaria. It is unclear if intravenous N-acetyl cysteine is beneficial as an adjunct in treating malaria. Oral N-acetyl cysteine has not been evaluated for this use. Details: One small clinical study shows that intravenous N-acetyl cysteine, in combination with intravenous artesunate, does not reduce symptoms or the risk of mortality in patients with severe malaria when compared with artesunate alone (64630).
• Male infertility. It is unclear of oral N-acetyl cysteine is beneficial for male infertility. Details: Clinical research in adults with idiopathic oligoasthenoteratospermia shows that taking N-acetyl cysteine 600 mg orally daily for 26 weeks improves sperm concentration, but not sperm motility, when compared with placebo (64626). Additionally, a preliminary clinical study in adults with asthenoteratozoospermia shows that taking N-acetyl cysteine 600 mg daily for 3 months improves sperm motility and concentration, increases protamine, and improves hormone levels and sperm morphology when compared to baseline (99534). The validity of this study is limited by the lack of a comparator group. There is also interest in using N-acetyl cysteine to attenuate the infertility effects observed after COVID-19 infection. A large clinical study in males who had normal sperm analysis prior to COVID-19, but with significantly lower sperm parameters within 6 weeks after infection, shows that taking oral N-acetyl cysteine 600 mg daily for 3 months improves sperm volume, concentration, morphology, and total motility when compared with baseline post-COVID-19 levels (108447). Although the study enrolled a control group, the investigators did not provide a statistical comparison of outcomes between groups, limiting the validity of this finding.
• Mercury toxicity. Although there has been interest in using oral N-acetyl cysteine for mercury toxicity, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Miscarriage. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its benefit when used alone is unclear. Details: One small clinical trial shows that taking oral N-acetyl cysteine 600 mg daily with folic acid 500 mcg daily improves the likelihood of maintaining pregnancy past 20 weeks when compared with folic acid alone in adults with a history of recurrent pregnancy loss (64616).
• Multiple sclerosis (MS). It is unclear if oral and intravenous N-acetyl cysteine are beneficial in patients with MS. Details: One clinical trial in a small group of patients with MS shows that intravenous and oral N-acetyl cysteine in addition to standard care for 2 months improves self-reported cognition by a moderate amount when compared with standard care alone. Self-reported attention also seems to improve (102657).
• Nitrate tolerance. Intravenous N-acetyl cysteine seems to reduce the development of nitrate tolerance. Oral N-acetyl cysteine has shown mixed results for this use. Details: Some clinical research shows that concurrent intravenous or oral administration of N-acetyl cysteine reduces the development of nitroglycerin tolerance (832,2245,64546). However, other research suggests that oral N-acetyl cysteine does not reduce the development of nitroglycerin tolerance in patients with angina (2281,2282).
• Nonalcoholic steatohepatitis (NASH). It is unclear if oral N-acetyl cysteine is beneficial in patients with NASH. Details: One small clinical study in patients with NASH shows that taking N-acetyl cysteine 1.2 grams with metformin 850-1500 mg daily for 48 weeks reduces NASH activity scores and measures of steatosis and hepatocellular ballooning, but not inflammation or fibrosis, when compared to baseline. However, taking the same dose of N-acetyl cysteine and metformin along with ursodeoxycholic acid 15 mg/kg daily does not improve these outcomes, or improve liver enzyme levels, when compared with baseline (102026). The reasons for these disparate findings are unclear. Inadequate statistical power and the lack of a comparator group limit the validity of these findings.
• Obsessive-compulsive disorder (OCD). Oral N-acetyl cysteine might improve some symptoms of OCD when used with fluvoxamine in adults. Its effects when used in combination with other psychiatric medications or as monotherapy in children and adults is unclear. Details: Preliminary clinical research in adults shows that taking N-acetyl cysteine 1000 mg twice daily along with fluvoxamine 200 mg daily for 10 weeks modestly reduces overall symptoms of OCD and symptoms of obsession when compared with fluvoxamine alone. However, the addition of N-acetyl cysteine is not associated with an improvement in symptoms of compulsion, nor with a statistically significant increase in partial or complete responders, when compared with fluvoxamine alone (97048). A clinical trial in adults with OCD who are taking various psychiatric medications shows that adding oral N-acetyl cysteine 2000-4000 mg daily for 20 weeks does not reduce symptoms of OCD, or improve secondary outcomes such as anxiety, mood, functioning, or quality of life, when compared with placebo (108450). Over half (63%) of patients had a comorbid psychiatric diagnosis, limiting the applicability of these findings. Other preliminary clinical research in adults with moderate to severe OCD who are taking various psychiatric medications shows that taking N-acetyl cysteine 3000 mg daily for 16 weeks does not improve OCD symptoms when compared with placebo (97045). A very small preliminary clinical trial in children aged 8-17 years, most of whom are not taking psychiatric medications, shows some benefit for symptom reduction when N-acetyl cysteine 2700 mg daily for 12 weeks is compared with placebo (102656).
• Otitis media. Although there has been interest in using ear drops containing N-acetyl cysteine for otitis media, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Polycystic ovary syndrome (PCOS). Oral N-acetyl cysteine might improve pregnancy-related outcomes in PCOS, although it appears to be less effective than metformin. Evidence on its benefits for other symptoms of PCOS is conflicting. Details: Some research in patients with PCOS shows that N-acetyl cysteine can increase insulin sensitivity, improve hirsutism, and improve menstrual irregularity (64435,64550,91245,102121). It may also improve fasting insulin levels, but results are conflicting (64435,64550,91245). Other research shows that N-acetyl cysteine, alone or as a specific combination product (Ovaric HP, Just Pharma), increases ovulation rates in some, but not all, patients with PCOS (64480,64550,64553,91246,91247,102121). A meta-analysis of clinical research suggests that N-acetyl cysteine increases the odds of having a live birth, getting pregnant, and/or ovulating by about 3-fold when compared with placebo. Its effects on the odds of pregnancy and ovulation appear to be greater in those resistant to clomiphene citrate. However, when compared with metformin, N-acetyl cysteine appears to decrease the odds of getting pregnant by about 60% and decrease the odds of ovulation by about 87%. N-acetyl cysteine also does not appear to reduce the rate of miscarriage, menstrual irregularity, or the severity of acne or hirsutism in people with PCOS (93057). Another meta-analysis shows that N-acetyl cysteine in various doses is associated with an insignificant improvement in ovulation and pregnancy rate, multiple pregnancy rate, and miscarriage rate, and is less efficacious than metformin for all of these outcomes (106888).
• Post-traumatic stress disorder (PTSD). It is unclear if oral N-acetyl cysteine is beneficial in veterans with PTSD. Details: A small clinical study in veterans with PTSD and a history of substance use disorders shows that taking N-acetyl cysteine 1200 mg orally twice daily for 8 weeks while receiving cognitive behavioral therapy reduces depressive symptoms and the rate of self-reported PTSD symptoms when compared with cognitive behavioral therapy plus placebo. Additionally, receiving N-acetyl cysteine reduces the amount and frequency of cravings by 81% and 72%, respectively, compared to a reduction of 32% and 29% for those receiving cognitive behavioral therapy with placebo. The use of N-acetyl cysteine did not impact the intensity of cravings or the actual rate of substance use during the study, which was low for all patients (97037).
• Postmenopausal conditions. It is unclear if oral N-acetyl cysteine is beneficial for preventing postmenopausal bone loss. Details: One small clinical trial shows that taking N-acetyl cysteine 2 grams daily for 3 months does not reduce postmenopausal bone loss when compared with placebo (64576).
• Preterm labor. It is unclear if oral N-acetyl cysteine is beneficial for reducing the risk for preterm labor. Details: Some clinical research shows that taking N-acetyl cysteine 0.6 grams daily orally in combination with 17-hydroxyprogesterone caproate (17-OHPC), beginning at 16 to 18 weeks gestation and continuing until active labor, increases the likelihood of reaching 36 weeks gestation and increases gestational age at delivery in adults with previous preterm labor and bacterial vaginosis when compared with 17-OHPC alone (64615). However, taking oral N-acetyl cysteine 0.6 grams every 8 hours, beginning at 25 to 33 weeks gestation and continuing until delivery, does not improve the treatment-to-delivery interval when compared with placebo in adults with early onset severe pre-eclampsia and/or HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome (64493).
• Radiation-induced sialadenitis. It is unclear if mouthwash containing N-acetyl cysteine is beneficial for reducing dry mouth during chemoradiotherapy. Details: One clinical trial in a small group of patients undergoing chemoradiotherapy for head and neck cancer shows that using a mouth rinse containing N-acetyl cysteine 500 mg five times daily during radiotherapy and 2 weeks postradiotherapy improves daytime and total sticky saliva and feelings of dry mouth by up to 38% when compared with placebo. However, N-acetyl cysteine does not seem to improve nighttime symptoms (102661).
• Schizophrenia. Oral N-acetyl cysteine seems to improve negative symptoms of schizophrenia. The benefits of N-acetyl cysteine on positive symptoms of schizophrenia are less clear. Details: A meta-analysis of clinical research shows that taking N-acetyl cysteine for at least 6 months has a small to moderate effect on negative symptoms when compared with placebo. However, taking N-acetyl cysteine for only 8 weeks does not reduce negative symptoms, suggesting that a longer duration of treatment may be necessary (102658). Individual clinical studies show that N-acetyl cysteine does not improve positive symptoms, social function, cognition, and clinical global impression when compared with placebo (64605,99528). However, a meta-analysis of available research shows that taking N-acetyl cysteine for any duration has a small effect on positive symptoms, a moderate effect on working memory, and a large effect on overall symptoms (102658). It is possible that many individual studies were underpowered to detect a difference.
• Sepsis. Small clinical studies suggest that intravenous N-acetyl cysteine may improve respiratory function and tissue oxygenation, but not mortality, in patients with septic shock. Details: Two small clinical studies show that intravenous N-acetyl cysteine might improve respiratory function and tissue oxygenation, but not mortality, in some patients with recently diagnosed septic shock when compared with placebo (64760,64797).
• Sjogren syndrome. Small clinical studies suggest that oral N-acetyl cysteine may improve ocular and oral manifestations of this condition. Details: Two small clinical studies in adults with Sjogren syndrome show that taking oral N-acetyl cysteine 200 mg three times daily for 4 weeks reduces eye soreness and irritability, bad breath, and daytime thirst when compared with a control group; however, objective signs of dry eye were not improved (64673,64812).
• Systemic lupus erythematosus (SLE). It is unclear if oral N-acetyl cysteine is beneficial in patients with SLE. Details: One small clinical trial shows that taking N-acetyl cysteine orally 2.4-4.8 grams daily for 3 months significantly reduces disease activity and fatigue when compared with placebo in patients with SLE (91242).
• Thrombocytopenia. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients, its effect when used alone is unclear. Details: A very small clinical study in adults with primary immune thrombocytopenia resistant or refractory to steroid therapy shows taking N-acetyl cysteine 400 mg every 8 hours with atorvastatin daily for at least one month at least doubles platelet count or increases it above 30 × 109/L compared to baseline in 60% of participants. However, 40% of participants did not respond to treatment (111572). It is unclear if this effect is due to N-acetyl cysteine, atorvastatin, or the combination. The validity of these findings is limited by the very small sample size, insufficient randomization, lack of a comparator group, and low retention rate, especially in the non-responder group.
• Tourette syndrome. It is unclear if oral N-acetyl cysteine is beneficial in patients with this condition. Details: One small clinical trial in children 8-17 years of age with Tourette syndrome shows that taking N-acetyl cysteine 600 mg twice daily for 2 weeks, followed by 1200 mg twice daily for the next 10 weeks, does not improve tic symptoms, premonitory urges, or the comorbid symptoms of obsessive-compulsive disorder (OCD), attention deficit-hyperactivity disorder (ADHD), anxiety, or depression when compared with placebo (97040).
• Trichotillomania. Oral N-acetyl cysteine might offer some benefit to adults, but not children, with trichotillomania. Details: One small clinical trial in adults shows that taking N-acetyl cysteine orally, in doses up to 2400 mg daily, significantly decreases the urge to pull hair, the amount of hair pulled, and patients' perception of their control over hair pulling as measured by a self-rating scale. After 12 weeks of treatment, scores decreased by 40% (16840). However, in children, taking N-acetyl cysteine in doses up to 2400 mg daily for 12 weeks does not seem to improve hair pulling when compared with placebo (91235).
• Ulcerative colitis. It is unclear if oral N-acetyl cysteine is beneficial in patients with ulcerative colitis. Details: One small clinical trial shows that oral N-acetyl cysteine 0.8 grams daily in combination with mesalamine 2.4 grams daily for 4 weeks does not improve the rate of clinical remission in individuals with ulcerative colitis when compared with mesalamine alone (64606).
• Urinary tract infections (UTIs). Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Observational research in female breast cancer survivors has found that taking the combination of D-mannose 500 mg, N-acetyl cysteine 100 mg, and Morinda citrifolia fruit extract 200 mg daily for 2 months in addition to antibiotic therapy is associated with reduced recurrence of UTIs and urinary discomfort when compared with antibiotics alone (97360).
• Uterine fibroids. It is unclear if oral N-acetyl cysteine is beneficial in patients with uterine fibroids. Details: Preliminary clinical research shows that taking N-acetyl cysteine 600 mg daily for 12 weeks reduces the volume of uterine fibroids by about 25%, compared with a reduction of about 1% with placebo. N-acetyl cysteine also reduces painful and heavy menstrual bleeding when compared with placebo (106889).
• Wound healing. It is unclear if postoperative intravenous N-acetyl cysteine is beneficial in patients undergoing lower extremity amputation. Details: A clinical study in patients undergoing lower extremity amputation due to critical limb-threatening ischemia shows that receiving postoperative intravenous N-acetyl cysteine 1200 mg twice daily for 5 days, beginning within 3 hours after surgery, improves tissue perfusion from days 3 to 5 and amputation stump healing at day 30 in patients that are defined as high-risk, but not in the intent-to-treat population, when compared with placebo (108448). The validity of these findings is limited due to the short duration of treatment and the inclusion of both above-the-knee and below-the-knee amputations. More evidence is needed to rate N-acetyl cysteine for these uses.

(Read more about N-ACETYL CYSTEINE (NAC))

POSSIBLY EFFECTIVE

• Scarring. Clinical research in adults and children shows that topical application of onion extract, often as part of combination products, for 10 weeks to 6 months is beneficial for preventing scarring; however, the most effective combination of ingredients, dosage form, and dose are unclear. Details: Many small clinical trials show that using topical onion extract improves the appearance, as well as pain and itching, associated with postburn hypertrophic scars, keloidal scars, scars following tattoo removal, scars following Cesarean delivery, or scars following surgical removal of tissue when compared with control (66895,66918,66939,66951,66987,67089,67104,95151,95156,95159,104773). Products evaluated in clinical research have included gels containing a combination of onion extract, heparin, and allantoin (Contractubex, Merz Pharmaceuticals) (66895,66987,67089,67104,104773); a combination of onion extract and a silicone derivative (Cybele scagel, Bangkok Botanica) (95156,95159); a combination of onion extract, allantoin, pentaglycan, and a solution of glycosaminoglycans (Kaloidon gel, Laboratori Farmacologici Milanesi) (95151); and a transdermal patch containing a combination of onion extract and allantoin (104771). However, not all research agrees. A meta-analysis of randomized controlled trials using onion extract gel for scar management demonstrated mixed results when compared with control. However, the validity of the study is limited by high heterogeneity (109511). In addition, a specific product containing onion extract and allantoin (Mederma, Merz Pharmaceuticals) for 4-11 weeks does not appear to improve the appearance of new surgical scars (66742,66883). Similarly, observational research has found that a topical patch containing onion extract and allantoin is not associated with improved provider- or patient-assessed appearance of scars following cesarean-delivery after 4 weeks when compared with those using no scar treatment (104771). It is possible that the duration of treatment in these studies was inadequate to identify improvement.

POSSIBLY INEFFECTIVE

• Obesity. Clinical research does not support the use of dietary onion or onion supplements for weight loss. Details: Clinical research in overweight patients shows that taking capsules containing steamed onion (Oniro, Kunpoong Bio Co., Ltd) 300 mg orally three times daily for 12 weeks does not reduce body mass index (BMI), fat distribution, or fat mass when compared with placebo (101747). In addition, one clinical study in overweight and obese patients with polycystic ovary syndrome (PCOS) shows that eating raw red onion 80-120 grams daily can actually increase BMI by 0.36 kg/m2 when compared with eating 20-30 grams of raw red onion (95155). Clinical studies have also used onion products standardized by quercetin content. Preliminary clinical research in overweight and obese patients shows that taking onion peel extract providing quercetin 100 mg orally daily for 12 weeks reduces body weight by up to 1.1 kg and BMI by up to 0.4 kg/m2 when compared to baseline, but not when compared with placebo (95152,101748). Another small clinical study in healthy, overweight Japanese adults shows that taking an onion powder containing quercetin 60 mg orally daily for 12 weeks does not reduce body weight, BMI, abdominal circumference, or abdominal fat when compared with the same quantity of quercetin-free onion powder (104772).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alopecia areata. It is unclear if topical onion is beneficial in patients with alopecia areata. Details: Preliminary clinical research in children and adults with alopecia areata shows that topical application of raw onion juice twice daily for 8 weeks improves hair growth when compared with placebo. Hair regrowth was demonstrated in 74% of subjects using onion juice, compared with 13% using placebo (66797).
• Angina. Although there has been interest in using oral onion for angina, there is insufficient reliable information about the clinical effects of onion for this purpose.
• Asthma. Although there has been interest in using oral onion for asthma, there is insufficient reliable information about the clinical effects of onion for this purpose.
• Atherosclerosis. Although there has been interest in using oral onion for atherosclerosis, there is insufficient reliable information about the clinical effects of onion for this purpose.
• Bruises. Although there has been interest in using topical onion for bruises, there is insufficient reliable information about the clinical effects of onion for this purpose.
• Diabetes. It is unclear if oral onion is beneficial in patients with diabetes. Details: Preliminary clinical research in adults with type 2 diabetes shows that taking fresh onion 20 grams orally three times daily, in addition to consuming a controlled diet, for 8 weeks decreases blood glucose levels by 5% when compared with a controlled diet alone (67072).
• Dyspepsia. Although there has been interest in using oral onion for dyspepsia, there is insufficient reliable information about the clinical effects of onion for this purpose.
• Gastric cancer. It is unclear if oral onion is beneficial for preventing gastric cancer. Details: Population research has found that the highest dietary intake of onion is associated with a 48% reduced odds of gastric cancer when compared with the lowest intake (51460).
• Hypertension. It is unclear if oral onion is beneficial in patients with hypertension. Details: Preliminary clinical research in overweight or obese adults with prehypertension or hypertension shows that taking onion skin extract 132 mg orally three times daily for 6 weeks reduces 24-hour systolic blood pressure by 4 mmHg, but does not affect diastolic blood pressure, when compared with placebo (95149). Other preliminary clinical research in patients with hypertension shows that taking a specific product (Campo di mele formula, Phyt-Immun) containing onion 2.5 grams, olive oil 5 mL, grape skin extract 50 mg, L-carnitine 30 mg, vitamin E 3 mg, vitamin C 2 mg, lycopene 1 mg, and folic acid 44 mcg, once daily for one week, decreases systolic and diastolic blood pressure by 5 mmHg and 2 mmHg, respectively, when compared with placebo (66766). It is unclear if this effect is due to onion, other ingredients, or the combination.
• Hypothyroidism. It is unclear if oral onion is beneficial for preventing hypothyroidism. Details: Population research in females has found that high dietary intake of onion is associated with a lower risk of subclinical hypothyroidism when compared with low dietary intake, However, this association was not identified in males. The association of dietary onion intake with symptomatic hypothyroidism was not evaluated (109512).
• Insect bite. Although there has been interest in using topical onion for insect bites, there is insufficient reliable information about the clinical effects of onion for this purpose.
• Insomnia. It is unclear if oral onion is beneficial in patients with poor sleep quality. Details: Preliminary clinical research in healthy adults that were unsatisfied with their current sleep quality shows that taking onion extract 500 mg orally three times daily for 5 days may slightly improve sleep latency and waking after sleep onset, but does not change self-rated sleep quality, when compared with placebo (104774).
• Polycystic ovary syndrome (PCOS). It is unclear if oral onion is beneficial in patients with PCOS. Details: Clinical research in overweight or obese adults with PCOS shows that eating 80-120 grams of raw red onion daily does not improve levels of fasting blood glucose, cholesterol, triglycerides, or lipoprotein (a), and can increase body mass index (BMI) by 0.36 kg/m2, when compared with eating 20-30 grams of raw red onion daily (95155).
• Prostate cancer. It is unclear if oral onion is beneficial for preventing prostate cancer. Details: Population research has found that high dietary intake of onion is not associated with a lower odds of developing prostate cancer when compared with low dietary intake of onion (88410).
• Respiratory tract infections. Although there has been interest in using oral onion for respiratory tract infections, including the common cold, there is insufficient reliable information about the clinical effects of onion for this purpose.
• Stretch marks (striae distensae). Topical onion has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adult females shows that applying a specific cream (Mederma For Stretch Marks, Merz Pharmaceuticals) containing onion extract, gotu kola, and hyaluronic acid to striae rubra twice daily for 12 weeks improves stretch mark scores, including color, softness, and texture, when compared with no treatment (95154).
• Warts. Although there has been interest in using topical onion for warts, there is insufficient reliable information about the clinical effects of onion for this purpose. More evidence is needed to rate onion for these uses.

(Read more about ONION)

EFFECTIVE

• Sunburn. Topical PABA prevents sunburn. Details: PABA is an FDA-approved sunscreen (266,8952). PABA seems to be effective during sweating, but not when skin is immersed in water (272). PABA sunscreens can be applied topically in concentrations of 1% to 15% (272).

POSSIBLY EFFECTIVE

• Peyronie disease. Low quality clinical research shows that oral PABA improves Peyronie disease symptoms. Details: PABA is FDA-approved for use in this condition. Clinical research shows that taking the specific PABA product (POTABA, Glenwood LLC.), 3 grams orally four times a day for 8-12 months can reduce penile curvature and deterioration when compared with placebo (1067,8951,67982).

POSSIBLY INEFFECTIVE

• Scleroderma. Clinical research is conflicting, but suggests that oral PABA is not effective for treating scleroderma. Details: Although PABA is FDA-approved for scleroderma, as well as morphea, a localized form of scleroderma, evidence supporting its use is limited. Some retrospective studies suggest it might help for some symptoms of scleroderma, but higher quality evidence shows that it is not beneficial (1071,1073,1074,1075).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. Although there has been interest in using oral PABA for aging skin, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Constipation. Although there has been interest in using oral PABA for constipation, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Headache. Although there has been interest in using oral PABA for headache, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Herpes keratitis. Although there has been interest in using ophthalmic PABA for herpes keratitis, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Infertility. Although there has been interest in using oral PABA for infertility, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Inflammatory myopathies. It is unclear if oral PABA is beneficial in patients with inflammatory myopathies. Details: PABA is FDA-approved for use in dermatomyositis, a type of inflammatory myopathy, but there is limited evidence to support this use (10). PABA is taken as 12 grams orally daily in 4 to 6 divided doses in adults or 220 mg/kg orally daily in 4 to 6 divided doses in children (10).
• Pemphigus. It is unclear if oral PABA is beneficial in patients with pemphigus. Details: PABA is FDA-approved for use in pemphigus, but there is limited evidence to support this use (10). PABA is taken as 12 grams orally daily in 4 to 6 divided doses in adults or 220 mg/kg orally daily in 4 to 6 divided doses in children (10).
• Systemic lupus erythematosus (SLE). Although there has been interest in using oral PABA for SLE, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Vitiligo. Although there has been interest in using oral PABA for vitiligo, there is insufficient reliable information about the clinical effects of PABA for this purpose. More evidence is needed to rate PABA for these uses.

(Read more about PARA-AMINOBENZOIC ACID (PABA))

There is insufficient reliable information available about the effectiveness of pleurisy root.

(Read more about PLEURISY ROOT)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). Although there has been interest in using oral skullcap for allergic rhinitis (hay fever), there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Anxiety. It is unclear if oral skullcap is beneficial for reducing symptoms of anxiety. Details: Preliminary clinical research shows that healthy people who take a single dose of freeze-dried skullcap extract 100-350 mg feel more relaxed when compared to baseline. This effect appears to last for about 2 hours (12216). However, other preliminary clinical research in healthy patients shows that taking freeze-dried skullcap (Skullcap, Eclectic Institute) 350 mg three times daily for 2 weeks does not reduce anxiety scores when compared with placebo (91690). Because these were short-term studies in healthy patients, it's unclear if skullcap is beneficial in anxiety disorders or if extended use is beneficial.
• Atherosclerosis. Although there has been interest in using oral skullcap for atherosclerosis, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Contact dermatitis. Although there has been interest in using oral skullcap for contact dermatitis, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Epilepsy. Although there has been interest in using oral skullcap for epilepsy, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Hyperlipidemia. Although there has been interest in using oral skullcap for hyperlipidemia, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Insomnia. Although there has been interest in using oral skullcap for insomnia, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Premenstrual dysphoric disorder (PMDD). Although there has been interest in using oral skullcap for PMDD, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Spasticity. Although there has been interest in using oral skullcap for spasticity, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Stress. Although there has been interest in using oral skullcap for stress, there is insufficient reliable information about the clinical effects of skullcap for this purpose.
• Stroke. Although there has been interest in using oral skullcap for stroke, there is insufficient reliable information about the clinical effects of skullcap for this purpose. More evidence is needed to rate skullcap for this use.

(Read more about SKULLCAP)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. It is unclear if a topical thyme flower and leaf extract reduces wrinkles. Details: A small clinical trial in healthy females aged 40-60 years with wrinkles shows that applying a specific gel preparation (ThymLec 2%, PhytoPharmaTech) containing thyme flower and leaf 1-3% extract in lecithin on the face twice daily for 60 days reduces facial wrinkles when compared with inactive control gel, but not when compared with an active comparator gel containing propanediol, ornithine, phospholipids, and glycolipids (105909).
• Alopecia areata. Topical thyme oil has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study shows that applying a combination of the essential oils from thyme, rosemary, lavender, and cedarwood improves hair growth in up to 44% of patients after 7 months of treatment when compared with baseline (5177). The validity of this finding is limited by the lack of a comparator group. Additionally, it is unclear if this effect is due to thyme, other ingredients, or the combination.
• Bronchitis. Oral thyme has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some research has evaluated thyme in combination with cowslip. One observational study in adults and children has found that taking a specific product (Bronchipret) containing thyme and cowslip relieves symptoms of bronchitis and increases production of sputum (13557). A clinical study in patients with acute bronchitis shows that taking a similar combination extract (Bronchicum Tropfen) containing thyme and cowslip root 1 mL five times daily for 7-9 days seems to reduce severity and duration of coughing when compared with placebo (49219). Other thyme and cowslip preparations such as Bronchicum Elixir S and Bronchcium Tropfen seem to be similarly beneficial for bronchitis (49223). Thyme has also been studied in combination with other ingredients. A large clinical study in patients with acute bronchitis shows that taking a specific syrup (Bronchipret Saft, Bionorica AG) containing thyme and English ivy leaf 5.4 mL three times daily for 11 days reduces the frequency and duration of cough when compared with placebo (78152). Additionally, an observational study in children with acute bronchitis has found that taking this combination product in an age-specific dosing schema is associated with reduced bronchitis severity and coughing fits when compared to baseline (78181). However, due to the lack of a comparator group, it is unclear if these changes are due to the product or to the natural resolution of the condition.
• Colic. Although there is interest in using oral thyme for colic, there is insufficient reliable information about the clinical effects of thyme for this condition.
• Cough. Oral thyme has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large open-label, uncontrolled study in adults with acute cough due to an upper respiratory tract infection who purchased a specific syrup (Bronchipret drops, Bionorica AG) containing thyme and English ivy leaf extracts suggests that taking this product as 2.6 mL three times daily for at least 4 days may improve patient-reported bronchitis symptom severity, cough severity, and quality of life, with over 90% of patients reporting overall satisfaction and product tolerability (110401). However, due to the lack of a comparator group, it is unclear if these changes are due to the product or the natural resolution of the condition. Additionally, the validity of these findings is limited by poor study methodology.
• Common cold. Although there is interest in using oral thyme for the common cold, there is insufficient reliable information about the clinical effects of thyme for this condition.
• Dementia. It is unclear if aromatherapy with thyme oil is beneficial in patients with dementia. Details: One very small clinical study in patients with advanced dementia shows that attaching a pad containing thyme oil to the collar area of the shirt does not reduce agitation when compared with lavender oil or unscented grapeseed oil (12213).
• Developmental coordination disorder (DCD). Oral thyme oil has only been evaluated in combination with other oils; its effect when used alone is unclear. Details: One very small clinical study in children with DCD shows that taking thyme oil, in combination with evening primrose oil, fish oil, and vitamin E (Efalex, Efamol Ltd.), seems to modestly improve movement disorders when compared with baseline (5708). The validity of this finding is limited by the lack of a comparator group. Additionally, it is unclear if this effect is due to thyme, other ingredients, or the combination.
• Dyspepsia. Although there is interest in using oral thyme for dyspepsia, there is insufficient reliable information about the clinical effects of thyme for this condition.
• Dysmenorrhea. It is unclear if drinking thyme tea is beneficial for the prevention of dysmenorrhea. Details: One small observational study in adolescents living in Ethiopia has found that drinking thyme tea is associated with a lower occurrence of primary dysmenorrhea when compared with those who did not drink thyme tea (105910).
• Halitosis. It is unclear whether oral thyme is beneficial for halitosis. Details: One small retrospective study in adults with gingival halitosis who received periodontal treatment and oral hygiene instructions suggests that drinking thyme tea twice daily for 1 week is associated with a reduction in volatile sulfur compounds, which is a marker for halitosis, when compared with chlorhexidine or oral hygiene alone (111716). However, the interpretation of this finding is limited by the lack of thyme dosing information and the narrow focus on intraoral halitosis, excluding most extraoral halitosis-associated conditions.
• Laryngitis. Although there is interest in using oral and topical thyme for laryngitis, there is insufficient reliable information about the clinical effects of thyme for this condition.
• Oral mucositis. Although there is interest in using oral and topical thyme for oral mucositis, there is insufficient reliable information about the clinical effects of thyme for this condition.
• Tonsillitis. Although there is interest in using oral and topical thyme for tonsillitis, there is insufficient reliable information about the clinical effects of thyme for this condition. More evidence is needed to rate thyme for these uses.

(Read more about THYME)

POSSIBLY SAFE ...when the leaves are used orally and appropriately, short-term (4,6,12).

LIKELY UNSAFE ...when large amounts are used long-term. Chronic ingestion of alfalfa has been associated with drug-induced lupus effects (381,14828,30602).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in medicinal amounts. Alfalfa contains constituents with possible estrogenic activity (4,11,30592).

(Read more about ALFALFA)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Black pepper has Generally Recognized as Safe (GRAS) status in the US (4912).

POSSIBLY SAFE ...when black pepper oil is applied topically. Black pepper oil is nonirritating to the skin and is generally well tolerated (11). ...when black pepper oil is inhaled through the nose or as a vapor through the mouth, short-term. Black pepper oil as a vapor or as an olfactory stimulant has been used with apparent safety in clinical studies for up to 3 days and 30 days, respectively (29159,29160,29161,90502). There is insufficient reliable information available about the safety of black pepper when used orally in medicinal amounts.

CHILDREN: LIKELY SAFE
when used orally in amounts commonly found in foods (11).

CHILDREN: POSSIBLY UNSAFE
when used orally in large amounts. Fatal cases of pepper aspiration have been reported in some patients (5619,5620). There is insufficient reliable information available about the safety of topical pepper oil when used in children.

PREGNANCY: LIKELY SAFE
when used orally in amounts commonly found in foods (11).

PREGNANCY: LIKELY UNSAFE
when used orally in large amounts. Black pepper might have abortifacient effects (11,19); contraindicated. There is insufficient reliable information available about the safety of topical pepper when used during pregnancy.

LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods (11). There is insufficient reliable information available about the safety of black pepper when used in medicinal amounts during breast-feeding.

(Read more about BLACK PEPPER)

LIKELY SAFE ...when used orally in amounts typically found in food. Capsicum has Generally Recognized as Safe (GRAS) status in the US (4912). ...when used topically and appropriately (7038,10650,105345). The active capsicum constituent capsaicin is an FDA-approved ingredient used in certain over-the-counter, topical preparations (272).

POSSIBLY SAFE ...when used orally and appropriately, short-term in medicinal amounts. A specific sustained-release chili extract (Capsifen) has been used safely in doses of up to 200 mg daily, for up to 28 days (105196). ...when used intranasally and appropriately, short-term. Capsicum-containing nasal sprays, suspensions, and swabs seem to be safe when applied multiple times over 24 hours or when applied daily or every other day for up to 14 days. Although no serious side effects have been reported in clinical trials, intranasal application of capsicum-containing products can be very painful (14322,14324,14328,14329,14351,14352,14353,14356,14357) (14358,14359,14360,15016,105204). POSSIBLY UNSAFE when used orally, long-term or in high doses. There is concern that long-term use or use of excessive doses might be linked to hepatic or kidney damage, as well as hypertensive crisis (12404,40569,40606). There is insufficient reliable information available about the safety of capsicum when injected.

CHILDREN: POSSIBLY UNSAFE
when used topically in children under 2 years old (272). There is insufficient reliable information available about the safety of capsicum when used orally in children.

PREGNANCY: LIKELY SAFE
when used topically and appropriately (272).

PREGNANCY: POSSIBLY SAFE
when used orally and appropriately, short-term. Capsicum 5 mg daily has been used for up to 28 days during the latter half of the second trimester and the third trimester (96457).

LACTATION: LIKELY SAFE
when used topically and appropriately (272).

LACTATION: POSSIBLY UNSAFE
when used orally. Dermatitis can sometimes occur in infants when foods heavily spiced with capsicum peppers are ingested during lactation (739). Also, observational research suggests that intake of raw capsicum peppers during pregnancy is associated with an increased risk of sensitization to inhalant allergens in children by the age of 2 years (41021).

(Read more about CAPSICUM)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Fenugreek has Generally Recognized as Safe (GRAS) status in the US (4912).

POSSIBLY SAFE ...when the seed is used orally in medicinal amounts. Fenugreek seed powder 5-10 grams daily has been used with apparent safety for up to 3 years. Fenugreek seed extract 1 gram daily has been used with apparent safety for up to 3 months (7389,9783,18359,18362,49868,90112,90113,90117,93419,93420)(93421,93422,93423,96065,103285,108704).

CHILDREN: LIKELY SAFE
when used orally in amounts commonly found in foods (4912). There is insufficient reliable information available about the safety of fenugreek when used in larger amounts. Unusual body and urine odor has been reported after consumption of fenugreek tea. Although the odor appears to be harmless, it may be misdiagnosed as maple syrup urine disease (9782,96068).

PREGNANCY: LIKELY UNSAFE
when used orally in amounts greater than those found in food. Fenugreek has potential oxytoxic and uterine stimulant activity (12531). There are case reports of congenital malformations, including hydrocephalus, anencephaly, cleft palate, and spina bifida, after consumption of fenugreek seeds during pregnancy (96068). Consumption of fenugreek immediately prior to delivery may cause the neonate to have unusual body odor. Although this does not appear to cause long-term sequelae, it may be misdiagnosed as maple syrup urine disease (9781,96068).

LACTATION: POSSIBLY SAFE
when used orally to stimulate lactation, short-term. Although most available clinical studies lack safety testing in the lactating parent or infant (12535,22569,22570), some evidence suggests that taking fenugreek 1725 mg three times daily orally for 21 days does not cause negative side effects in the infant (90115).

(Read more about FENUGREEK)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Licorice has Generally Recognized as Safe (GRAS) status in the US (4912).

POSSIBLY SAFE ...when licorice products that do not contain glycyrrhizin (deglycyrrhizinated licorice) are used orally and appropriately for medicinal purposes. Licorice flavonoid oil 300 mg daily for 16 weeks, and deglycyrrhizinated licorice products in doses of up to 4.5 grams daily for up to 16 weeks, have been used with apparent safety (6196,11312,11313,17727,100984,102960). ...when licorice products containing glycyrrhizin are used orally in low doses, short-term. Licorice extract 272 mg, containing glycyrrhizin 24.3 mg, has been used daily with apparent safety for 6 months (102961). A licorice extract 1000 mg, containing monoammonium glycyrrhizinate 240 mg, has been used daily with apparent safety for 12 weeks (110320). In addition, a syrup providing licorice extract 750 mg has been used twice daily with apparent safety for 5 days (104558). ...when applied topically. A gel containing 2% licorice root extract has been applied to the skin with apparent safety for up to 2 weeks. (59732). A mouth rinse containing 5% licorice extract has been used with apparent safety four times daily for up to one week (104564).

POSSIBLY UNSAFE ...when licorice products containing glycyrrhizin are used orally in large amounts for several weeks, or in smaller amounts for longer periods of time. The European Scientific Committee on Food recommends that a safe average daily intake of glycyrrhizin should not exceed 10 mg (108577). In otherwise healthy people, consuming glycyrrhizin daily for several weeks or longer can cause severe adverse effects including pseudohyperaldosteronism, hypertensive crisis, hypokalemia, cardiac arrhythmias, and cardiac arrest. Doses of 20 grams or more of licorice products, containing at least 400 mg glycyrrhizin, are more likely to cause these effects; however, smaller amounts have also caused hypokalemia and associated symptoms when taken for months to years (781,3252,15590,15592,15594,15596,15597,15599,15600,16058)(59731,59740,59752,59785,59786,59787,59792,59795,59805,59811)(59816,59818,59820,59822,59826,59828,59849,59850,59851,59867)(59882,59885,59888,59889,59895,59900,59906,97213,110305). In patients with hypertension, cardiovascular or kidney conditions, or a high salt intake, as little as 5 grams of licorice product or 100 mg glycyrrhizin daily can cause severe adverse effects (15589,15593,15598,15600,59726).

PREGNANCY: UNSAFE
when used orally. Licorice has abortifacient, estrogenic, and steroid effects. It can also cause uterine stimulation. Heavy consumption of licorice, equivalent to 500 mg of glycyrrhizin per week (about 250 grams of licorice per week), during pregnancy seems to increase the risk of delivery before gestational age of 38 weeks (7619,10618). Furthermore, high intake of glycyrrhizin, at least 500 mg per week, during pregnancy is associated with increased salivary cortisol levels in the child by the age of 8 years. This suggests that high intake of licorice during pregnancy may increase hypothalamic-pituitary-adrenocortical axis activity in the child (26434); avoid using.

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about LICORICE)

LIKELY SAFE ...when used orally, intravenously, intratracheally, or by inhalation and appropriately. N-acetyl cysteine is an FDA-approved prescription drug (832,1539,1705,1710,2245,2246,2252,2253,2254,2256)(2258,2259,2260,5808,6176,6611,7868,10270,10271,16840)(91243,91247,102027,102660,102666,99531).

CHILDREN: LIKELY SAFE
when used orally and appropriately. N-acetyl cysteine has been safely used at doses of 900-2700 mg daily for 8-12 weeks (91235,91239,91241,102666). ...when used intravenously and appropriately. Intravenous N-acetyl cysteine 140 mg/kg/day plus oral N-acetyl cysteine 70 mg/kg four times daily for up to 10 months has been safely used (64547).

PREGNANCY: POSSIBLY SAFE
when used orally, intratracheally, intravenously, or by inhalation. N-acetyl cysteine crosses the placenta, but has not been associated with adverse effects to the fetus (1711,64615,64493,97041). However, N-acetyl cysteine should only be used in pregnancy when clearly indicated, such as in cases of acetaminophen toxicity.

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about N-ACETYL CYSTEINE (NAC))

LIKELY SAFE ...when consumed in amounts commonly found in foods. Onion has Generally Recognized as Safe (GRAS) status in the US (4912). ...when onion extract is used topically (66742,66883,66895,66903,67089,95151,95154,95156).

POSSIBLY SAFE ...when onion extract is used orally and appropriately (2). Onion extract has been used safely in doses of 300 mg three times daily for up to 12 weeks (95149,101747).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using in amounts greater than used in foods.

(Read more about ONION)

LIKELY SAFE ...when used topically and appropriately. PABA is FDA approved for topical use and there have not been reports of significant toxicity (266,272).

POSSIBLY SAFE ...when used orally and appropriately (10). PABA is an FDA-approved drug, but some potentially serious side effects have been reported (10).

POSSIBLY UNSAFE ...when used orally in high doses. Doses greater than 12 grams per day have been associated with leukopenia (1061).

CHILDREN: LIKELY SAFE
when used topically and appropriately (266,272).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately (10). PABA is an FDA-approved drug for use in children, but serious side effects have been reported (10).

CHILDREN: POSSIBLY UNSAFE
when used orally in high doses. Doses greater than 220 mg/kg/day have been associated with fatal toxic effects (1061).

PREGNANCY AND LACTATION: LIKELY SAFE
when used topically and appropriately (266,272). There is insufficient reliable information available about the safety of the oral use of PABA during pregnancy and breast-feeding; avoid using.

(Read more about PARA-AMINOBENZOIC ACID (PABA))

POSSIBLY UNSAFE ...when used orally. Pleurisy root contains digitalis-like cardenolide glycosides (4). When taken in large doses, it can cause digitalis-like poisoning symptoms (18). Canadian regulations do not allow pleurisy root as an ingredient in oral products (12).

PREGNANCY: UNSAFE
when used orally (12). Pleurisy root might have uterine stimulant and estrogenic activity (19).

LACTATION: POSSIBLY UNSAFE
when used orally (12); avoid using.

(Read more about PLEURISY ROOT)

There is insufficient reliable information available about the safety of skullcap.

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

(Read more about SKULLCAP)

LIKELY SAFE ...when used in amounts commonly found in foods. Thyme has Generally Recognized as Safe (GRAS) status in the US (4912).

POSSIBLY SAFE ...when thyme is used orally and appropriately in supplemental amounts. Orally, thyme, in combination with other herbs, has been used safely for up to 23 days (13557,49219,49223,78133). ...when diluted thyme oil is used topically, short-term. Diluted thyme oil has been used with apparent safety for up to 7 months (5177). There is insufficient reliable information available about the safety of thyme oil when used orally or when inhaled.

CHILDREN: LIKELY SAFE
when used in amounts commonly found in foods. Thyme has Generally Recognized as Safe (GRAS) status in the US (4912).

CHILDREN: POSSIBLY SAFE
when thyme is used orally in medicinal amounts in combination with English ivy. Thyme has been used with apparent safety in combination with English ivy for up to 10 days (78181). There is insufficient reliable information available about the safety of thyme oil when used orally or topically in children.

PREGNANCY AND LACTATION: LIKELY SAFE
when used in amounts commonly found in foods. Thyme has Generally Recognized as Safe (GRAS) status in the US (4912). There is insufficient reliable information available about the safety of thyme when used in medicinal amounts during pregnancy and breast-feeding; avoid using.

(Read more about THYME)

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, alfalfa might increase the risk of hypoglycemia when taken with antidiabetes drugs.  Details Animal research suggests that alfalfa decreases blood sugar in diabetic mice (30605). Also, in one case report, a diabetic patient experienced hypoglycemia after consuming alfalfa extract (30608). Monitor blood glucose levels closely. Dose adjustments might be necessary.

CONTRACEPTIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, alfalfa might interfere with the activity of contraceptive drugs.  Details Alfalfa contains coumestrol, a phytoestrogen, and isoflavonoids, which have estrogenic effects (4,30592).

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, alfalfa might interfere with hormone therapy.  Details Alfalfa contains coumestrol, a phytoestrogen, and isoflavonoids, which have estrogenic effects (4,30592).

IMMUNOSUPPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, alfalfa might decrease the efficacy of immunosuppressive therapy.  Details In vitro research and human case reports suggest that alfalfa may have immunostimulant effects (12174,14828,14829).

PHOTOSENSITIZING DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of alfalfa with photosensitizing drugs might have additive effects.  Details Animal research suggests that excessive doses of alfalfa may increase photosensitivity, possibly due to its chlorophyll content (106043). It is unclear if this effect would be clinically relevant in humans.

WARFARIN (Coumadin) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Theoretically, alfalfa might reduce the anticoagulant activity of warfarin.  Details Alfalfa contains a large amount of vitamin K (4,6). This could theoretically interfere with the activity of warfarin.

(Read more about ALFALFA)

AMOXICILLIN (Amoxil, Trimox) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase the effects and side effects of amoxicillin.  Details Animal research shows that taking piperine, a constituent of black pepper, with amoxicillin increases plasma levels of amoxicillin (29269). This has not been reported in humans.

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase the risk of bleeding when taken with antiplatelet or anticoagulant drugs.  Details In vitro research shows that piperine, a constituent of black pepper, seems to inhibit platelet aggregation (29206). This has not been reported in humans.

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase the risk of hypoglycemia when taken with antidiabetes drugs.  Details Animal research shows that piperine, a constituent of black pepper, can reduce blood glucose levels (29225). Monitor blood glucose levels closely. Dose adjustments might be necessary.

ATORVASTATIN (Lipitor) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase blood levels of atorvastatin.  Details Animal research shows that taking piperine, a constituent of black pepper, 35 mg/kg can increase the maximum serum concentration of atorvastatin three-fold (104188). This has not been reported in humans.

CARBAMAZEPINE (Tegretol) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, black pepper might increase blood levels of carbamazepine, potentially increasing the effects and side effects of carbamazepine.  Details One clinical study in patients taking carbamazepine 300 mg or 500 mg twice daily shows that taking a single 20 mg dose of purified piperine, a constituent of black pepper, increases carbamazepine levels. Piperine may increase carbamazepine absorption by increasing blood flow to the GI tract, increasing the surface area of the small intestine, or inhibiting cytochrome P450 3A4 (CYP3A4) in the gut wall. Absorption was significantly increased by 7-10 mcg/mL/hour. The time to eliminate carbamazepine was also increased by 4-8 hours. Although carbamazepine levels were increased, this did not appear to increase side effects (16833). In vitro research also shows that piperine can increase carbamazepine levels by 11% in a time-dependent manner (103819).

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase the effects and side effects of cyclosporine.  Details In vitro research shows that piperine, a constituent of black pepper, increases the bioavailability of cyclosporine (29282). This has not been reported in humans.

CYTOCHROME P450 1A1 (CYP1A1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase levels of drugs metabolized by CYP1A1.  Details In vitro research suggests that piperine, a constituent of black pepper, inhibits CYP1A1 (29213). This has not been reported in humans.

CYTOCHROME P450 2B1 (CYP2B1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase levels of drugs metabolized by CYP2B1.  Details In vitro research suggests that piperine, a constituent of black pepper, inhibits CYP2B1 (29332). This has not been reported in humans.

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase levels of drugs metabolized by CYP2D6.  Details In vitro research suggests that some constituents of black pepper inhibit CYP2D6 (29207,29212,38375). This has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase levels of drugs metabolized by CYP3A4.  Details In vitro research shows that piperine, a constituent of black pepper, as well as the pepper fruit seem to inhibit CYP3A4 (14375,29212). This has not been reported in humans.

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, black pepper might increase blood levels of lithium due to its diuretic effects. The dose of lithium might need to be reduced.  Details Black pepper is thought to have diuretic properties (11).

NEVIRAPINE (Viramune) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Black pepper might increase blood levels of nevirapine.  Details Clinical research shows that piperine, a constituent of black pepper, increases the plasma concentration of nevirapine. However, no adverse effects were observed in this study (29209).

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase levels of P-glycoprotein substrates.  Details In vitro research shows that piperine, a constituent of black pepper, seems to inhibit P-glycoprotein (14375,29281,29283).

PENTOBARBITAL (Nembutal) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, black pepper might increase the sedative effects of pentobarbital.  Details Animal research shows that piperine, a constituent of black pepper, increases pentobarbital-induced sleeping time (29214).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Black pepper might increase blood levels of phenytoin.  Details Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption, slow elimination, and increase levels of phenytoin (537,14442). Taking a single dose of black pepper 1 gram along with phenytoin seems to double the serum concentration of phenytoin (14375). Consuming a soup with black pepper providing piperine 44 mg/200 mL of soup along with phenytoin also seems to increase phenytoin levels when compared with consuming the same soup without black pepper (14442).

PROPRANOLOL (Inderal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Black pepper might increase blood levels of propranolol.  Details Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and slow elimination of propranolol (538).

RIFAMPIN (Rifadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Black pepper might increase blood levels of rifampin.  Details Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and serum levels of rifampin (14375,29284).

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Black pepper might increase blood levels of theophylline.  Details Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and slow elimination of theophylline (538).

(Read more about BLACK PEPPER)

ACE INHIBITORS (ACEIs) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, using topical capsaicin may increase the risk of ACE inhibitor-induced cough.  Details There is one case report of a topically applied capsaicin cream contributing to the cough reflex in a patient using an ACEI (12414). However, it is unclear if this interaction is clinically significant.

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, capsicum may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details In vitro research shows that capsicum might increase the effects of antiplatelet drugs (12406,12407). Also, population research shows that capsicum is associated with an increased risk of self-reported bleeding in patients taking warfarin (12405,20348). However, clinical research shows that taking a single dose of capsaicin (Asian Herbex Ltd.), the active ingredient in capsicum, 400-800 mcg orally in combination with aspirin 500 mg does not decrease platelet aggregation when compared with taking aspirin 500 mg alone. Also, there was no notable effect on measures of platelet aggregation with capsaicin (92990). It is unclear whether capsaicin must be used in more than a single dose to affect platelet aggregation.

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking capsicum with antidiabetes drugs might increase the risk of hypoglycemia.  Details Preliminary clinical research shows that consuming capsicum 5 grams along with a glucose drink attenuates the rise in plasma glucose after 30 minutes by 21%, decreases the 2-hour postprandial area under the curve of plasma glucose by 11%, and increases the 2-hour postprandial area under the curve of plasma insulin by 58% in healthy individuals when compared with placebo (40453,40614). Other clinical research shows that taking capsicum 5 mg daily for 28 days significantly reduces postprandial blood glucose and insulin levels, but not fasting blood glucose and insulin levels, in patients with gestational diabetes (96457).

ASPIRIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking capsicum with aspirin might reduce the bioavailability of aspirin.  Details Animal research shows that acute or chronic intake of capsicum pepper reduces oral aspirin bioavailability (22617). This has not been shown in humans.

CIPROFLOXACIN (Cipro) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking capsicum with ciprofloxacin might increase levels and adverse effects of ciprofloxacin.  Details Animal research shows that concomitant use of capsaicin, the active constituent of capsicum, and ciprofloxacin increases the bioavailability of ciprofloxacin by up to 70% (22613).

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking capsicum with theophylline might increase the levels and adverse effects of theophylline.  Details In animal research, oral administration of capsicum reduced excretion of theophylline (12405). However, capsicum does not seem to affect the pharmacokinetics of theophylline when administered intravenously (22616).

(Read more about CAPSICUM)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, fenugreek might have additive effects when used with anticoagulant or antiplatelet drugs.  Details Some of the constituents in fenugreek have antiplatelet effects in animal and in vitro research. However, common fenugreek products might not contain sufficient concentrations of these constituents for clinical effects. A clinical study in patients with coronary artery disease or diabetes shows that taking fenugreek seed powder 2.5 grams twice daily for 3 months does not affect platelet aggregation, fibrinolytic activity, or fibrinogen levels (5191,7389,49643).

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, fenugreek seed might have additive hypoglycemic effects when used with antidiabetes drugs.  Details Clinical research shows that fenugreek seed can reduce fasting blood glucose and 2-hour postprandial glucose levels in adults with type 2 diabetes (10284,90112,96065,105016).

CLOPIDOGREL (Plavix) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fenugreek seed might alter the clinical effects of clopidogrel by inhibiting its conversion to the active form.  Details Animal research shows that fenugreek seed 200 mg/kg daily for 14 days increases the maximum serum concentration of clopidogrel by 21%. It is unclear how this affects the pharmacokinetics of the active metabolite of clopidogrel; however, this study found that concomitant use of fenugreek seed and clopidogrel prolonged bleeding time by an additional 11% (108701).

METOPROLOL (Toprol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, fenugreek seed might have additive hypotensive effects when used with metoprolol.  Details Animal research shows that fenugreek seed 300 mg/kg daily for 2 weeks decreases systolic and diastolic blood pressure by 9% and 11%, respectively, when administered alone, and by 15% and 22%, respectively, when given with metoprolol 10 mg/kg (108703).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fenugreek might decrease plasma levels of phenytoin.  Details Animal research shows that taking fenugreek seeds for 1 week decreases maximum concentrations and the area under the curve of a single dose of phenytoin by 44% and 72%, respectively. This seems to be related to increased clearance (110905). So far, this interaction has not been reported in humans.

SILDENAFIL (Viagra) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concurrent use of sildenafil and fenugreek might reduce levels and therapeutic effects of sildenafil.  Details Animal research shows that taking fenugreek seeds for 1 week reduces maximum concentrations and the area under the curve of a single dose of sildenafil by 27% and 48%, respectively (110898). So far, this interaction has not been reported in humans.

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fenugreek may reduce the levels and clinical effects of theophylline.  Details Animal research shows that fenugreek 50 grams daily for 7 days reduces the maximum serum concentration (Cmax) of theophylline by 28% and the area under the plasma drug concentration-time curve (AUC) by 22% (90118).

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, fenugreek might have additive effects with warfarin and increase the international normalized ratio (INR).  Details Some fenugreek constituents have antiplatelet effects, although these might not be present in concentrations that are clinically significant (7389). In one case report, a patient taking warfarin experienced an increased INR when starting to take fenugreek in combination with boldo (5191).

(Read more about FENUGREEK)

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, licorice might reduce the effects of antihypertensive drugs.  Details In human research, licorice increases blood pressure in a dose-dependent manner (1372,7620,59877).

CISPLATIN (Platinol-AQ) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might reduce the effects of cisplatin.  Details In animal research, licorice diminished the therapeutic efficacy of cisplatin (59763).

CORTICOSTEROIDS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of licorice and corticosteroids might increase the side effects of corticosteroids.  Details Case reports suggest that concomitant use of licorice and oral corticosteroids, such as hydrocortisone, can potentiate the duration of activity and increase blood levels of corticosteroids (3252,12672,20040,20042,48429,59756). Additionally, in one case report, a patient with neurogenic orthostatic hypertension stabilized on fludrocortisone 0.1 mg twice daily developed pseudohyperaldosteronism after recent consumption of large amounts of black licorice (108568).

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might decrease the levels and clinical effects of CYP1A2 substrates.  Details In vitro research shows that licorice induces CYP1A2 enzymes (111404).

CYTOCHROME P450 2B6 (CYP2B6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might increase levels of drugs metabolized by CYP2B6.  Details In vitro research shows that licorice extract and glabridin, a licorice constituent, inhibit CYP2B6 isoenzymes (10300,94822). Licorice extract from the species G. uralensis seems to inhibit CYP2B6 isoenzymes to a greater degree than G. glabra extract in vitro (94822). Theoretically, these species of licorice might increase levels of drugs metabolized by CYP2B6; however, these interactions have not yet been reported in humans.

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might increase levels of drugs metabolized by CYP2C19.  Details In vitro, licorice extracts from the species G. glabra and G. uralensis inhibit CYP2C19 isoenzymes in vitro (94822). Theoretically, these species of licorice might increase levels of drugs metabolized by CYP2C19; however, this interaction has not yet been reported in humans.

CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might increase levels of drugs metabolized by CYP2C8.  Details In vitro, licorice extract from the species G. glabra and G. uralensis inhibits CYP2C8 isoenzymes (94822). Theoretically, these species of licorice might increase levels of drugs metabolized by CYP2C8; however, this interaction has not yet been reported in humans.

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might increase or decrease levels of drugs metabolized by CYP2C9.  Details There is conflicting evidence about the effect of licorice on CYP2C9 enzyme activity. In vitro research shows that extracts from the licorice species G. glabra and G. uralensis moderately inhibit CYP2C9 isoenzymes (10300,94822). However, evidence from an animal model shows that licorice extract from the species G. uralensis can induce hepatic CYP2C9 activity (14441). Until more is known, licorice should be used cautiously in people taking CYP2C9 substrates.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, licorice might increase or decrease levels of drugs metabolized by CYP3A4.  Details Pharmacokinetic research shows that the licorice constituent glycyrrhizin, taken in a dosage of 150 mg orally twice daily for 14 days, modestly decreases the area under the concentration-time curve of midazolam by about 20%. Midazolam is a substrate of CYP3A4, suggesting that glycyrrhizin modestly induces CYP3A4 activity (59808). Animal research also shows that licorice extract from the species G. uralensis induces CYP3A4 activity (14441). However, licorice extract from G. glabra species appear to inhibit CYP3A4-induced metabolism of testosterone in vitro. It is thought that the G. glabra inhibits CYP3A4 due to its constituent glabridin, which is a moderate CYP3A4 inhibitor in vitro and not present in other licorice species (10300,94822). Until more is known, licorice should be used cautiously in people taking CYP3A4 substrates.

DIGOXIN (Lanoxin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of licorice with digoxin might increase the risk of cardiac toxicity.  Details Overuse or misuse of licorice with cardiac glycoside therapy might increase the risk of cardiac toxicity due to potassium loss (10393).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of licorice with diuretic drugs might increase the risk of hypokalemia.  Details Overuse of licorice might compound diuretic-induced potassium loss (10393,20045,20046,59812). In one case report, a 72-year-old male with a past medical history of hypertension, type 2 diabetes, hyperlipidemia, arrhythmia, stroke, and hepatic dysfunction was hospitalized with severe hypokalemia and uncontrolled hypertension due to pseudohyperaldosteronism. This was thought to be provoked by concomitant daily consumption of a product containing 225 mg of glycyrrhizin, a constituent of licorice, and hydrochlorothiazide 12.5 mg for 1 month (108577).

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might increase or decrease the effects of estrogen therapy.  Details Theoretically, licorice might interfere with estrogen therapy due to estrogenic and anti-estrogenic effects (7860,16058).

LOOP DIURETICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, loop diuretics might increase the mineralocorticoid effects of licorice.  Details Theoretically, loop diuretics might enhance the mineralocorticoid effects of licorice by inhibiting the enzyme that converts cortisol to cortisone; however, bumetanide (Bumex) does not appear to have this effect (3255).

METHOTREXATE (Trexall, others) Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, licorice might increase levels of methotrexate.  Details Animal research suggests that intravenous administration of glycyrrhizin, a licorice constituent, and high-dose methotrexate may delay methotrexate excretion and increase systemic exposure, leading to transient elevations in liver enzymes and total bilirubin (108570). This interaction has not yet been reported in humans.

MIDAZOLAM (Versed) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, licorice might decrease levels of midazolam.  Details In humans, the licorice constituent glycyrrhizin appears to moderately induce the metabolism of midazolam (59808). This is likely due to induction of cytochrome P450 3A4 by licorice. Until more is known, licorice should be used cautiously in people taking midazolam.

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might decrease the absorption of P-glycoprotein substrates.  Details In vitro research shows that licorice can increase P-glycoprotein activity (104561).

PACLITAXEL (Abraxane, Onxol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might decrease plasma levels and clinical effects of paclitaxel.  Details Multiple doses of licorice taken concomitantly with paclitaxel might reduce the effectiveness of paclitaxel. Animal research shows that licorice 3 grams/kg given orally for 14 days before intravenous administration of paclitaxel decreases the exposure to paclitaxel and increases its clearance. Theoretically, this occurs because licorice induces cytochrome P450 3A4 enzymes, which metabolize paclitaxel. Notably, a single dose of licorice did not affect exposure or clearance of paclitaxel (102959).

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, licorice might decrease plasma levels and clinical effects of warfarin.  Details Licorice seems to increase metabolism and decrease levels of warfarin in animal models. This is likely due to induction of cytochrome P450 2C9 (CYP2C9) metabolism by licorice (14441). Advise patients taking warfarin to avoid taking licorice.

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(Read more about MULLEIN)

ACTIVATED CHARCOAL Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D N-acetyl cysteine might reduce the effects of activated charcoal, while activated charcoal might reduce the absorption of N-acetyl cysteine.  Details N-acetyl cysteine appears to reduce the capacity of activated charcoal to adsorb acetaminophen and salicylic acid (7869). Conversely, although clinical research suggests that although activated charcoal can reduce the absorption of N-acetyl cysteine by up to 40%, it does not seem to reduce its clinical effects (1755,22774,22775,64501,64647). Other clinical evidence suggests that activated charcoal does not affect the absorption of N-acetyl cysteine (22776,22777).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, N-acetyl cysteine might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.  Details Clinical research suggests that intravenous N-acetyl cysteine decreases prothrombin time, prolongs coagulation time, decreases platelet aggregation, and increases blood loss in surgical patients (64511,64644). Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin (22780,64780).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, N-acetyl cysteine might increase the risk of hypotension when taken with antihypertensive drugs.  Details Animal research suggests that N-acetyl cysteine potentiates the hypotensive effects of the angiotensin-converting enzyme inhibitors (ACEIs) captopril and enalaprilat (22785). Theoretically, combining N-acetyl cysteine with other antihypertensive drugs might increase the risk of hypotension.

CHLOROQUINE (Aralen) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, N-acetyl cysteine might interfere with the antimalarial effects of chloroquine.  Details Animal research suggests that N-acetyl cysteine might reduce the antimalarial effects of chloroquine by increasing cellular levels of glutathione (22786).

NITROGLYCERIN Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B N-acetyl cysteine can increase the risk for hypotension and headaches when taken with intravenous or transdermal nitroglycerin.  Details Clinical research shows that concomitant administration of N-acetyl cysteine and intravenous or transdermal nitroglycerin can cause severe hypotension (2246) and intolerable headaches (2245,2280). Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin (22780,64780).

(Read more about N-ACETYL CYSTEINE (NAC))

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of anticoagulant or antiplatelet drugs with onion might increase the risk of bleeding.  Details In vitro research shows that onion inhibits platelet aggregation (19,66898).

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Concomitant use of antidiabetes drugs with onion may increase the risk of hypoglycemia.  Details Animal research and clinical research shows that taking onion can lower blood glucose levels (19,66800,66812,66859,66982,67033,67043,67053,67072,95148,95160). Monitor blood glucose levels closely.

ASPIRIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Concomitant use of aspirin with onion may worsen onion allergy.  Details In one case report, a patient with a mild onion allergy reported worsening allergy, including swelling and severe urticaria, after taking aspirin (5054).

CYTOCHROME P450 2E1 (CYP2E1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking onion might increase the levels and clinical effects of drugs metabolized by CYP2E1.  Details Animal research shows that taking onion powder inhibits CYP2E1 (19653). However, this interaction has not been reported in humans.

(Read more about ONION)

CORTISONE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of PABA and cortisone may increase the effects of cortisone.  Details Preliminary clinical research shows that PABA decreases the metabolism of cortisone (4488). Dose adjustments of cortisone may be necessary.

DAPSONE (Avlosulfon) Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = D Theoretically, concomitant use of PABA and dapsone may decrease the effects of dapsone.  Details Preliminary clinical research shows that PABA inhibits the antibacterial effects of dapsone (4488). Avoid concurrent use (266).

SULFONAMIDE ANTIBIOTICS Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = D Theoretically, concomitant use of PABA and sulfonamide antibiotics inhibits the antibacterial effects of sulfonamide.  Details Sulfonamide antibiotics competitively inhibit folic acid synthesis from PABA. Excess PABA may overcome the folate depleting effect of the sulfonamides (10). Avoid concurrent use.

(Read more about PARA-AMINOBENZOIC ACID (PABA))

(Read more about PLEURISY ROOT)

CNS DEPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, skullcap can have additive effects when used with other CNS depressants.  Details Animal and clinical research suggests that skullcap can cause sedation and cognitive impairment (12216,74008).

(Read more about SKULLCAP)

ANTICHOLINERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concurrent use of anticholinergic drugs and thyme essential oil might reduce the effects of anticholinergic drugs.  Details In vitro evidence suggests that thyme essential oil and specific essential oil constituents like thymohydroquinone and carvacrol can inhibit acetylcholinesterase (AChE) (78155). However, this effect has not been observed in humans.

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, thyme leaf extract might have additive effects with anticoagulant or antiplatelet drugs.  Details In vitro and animal research suggests that thyme leaf extract has antiplatelet effects (13457,18335,49445). However, this effect has not been observed in humans.

CHOLINERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concurrent use of cholinergic drugs and thyme essential oil might cause additive cholinergic effects.  Details In vitro evidence suggests that thyme essential oil and specific essential oil constituents like thymohydroquinone and carvacrol can inhibit acetylcholinesterase (AChE) (78155). However, this effect has not been observed in humans.

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, thyme might competitively inhibit the effects of estrogen replacement therapy.  Details In vitro research shows that thyme has estrogen receptor-binding activity and phytoestrogen content (3701). However, this effect has not been observed in humans.

(Read more about THYME)

General ...Orally, alfalfa leaf seems to be well tolerated. However, a thorough evaluation of safety outcomes has not been conducted.
Most Common Adverse Effects:
Orally: Abdominal discomfort, diarrhea, and flatulence.
Serious Adverse Effects (Rare):
Orally: Lupus-like syndrome after chronic ingestion of alfalfa.

Dermatologic ...Dermatitis associated with alfalfa use has been reported. In a 1954 publication, dermatitis was noted in a 61-year-old female consuming 4-6 cups of tea made with two tablespoonfuls of alfalfa seeds for approximately two months prior to onset. Examination revealed diffuse, confluent edema and erythema on the face, eyelids, ears, hands, forearms, and distal humeral regions. The dermatitis improved with treatment; re-exposure to alfalfa resulted in a similar reaction (30609).

Endocrine ...Alfalfa contains constituents, including coumestrol, with reported estrogenic activity (30586,30592,4753). Effects in humans are not known.
One case report documents hypokalemia in a female who had been drinking a "cleansing tea" containing alfalfa, licorice, and stinging nettle. The potassium level returned to normal after discontinuing the tea and initiating potassium supplementation. The specific cause of the hypokalemia is not clear. Notably, both stinging nettle and licorice have been associated with hypokalemia and may have been responsible for this effect (30562).

Gastrointestinal ...Orally, flatulence and bulkier feces were reported during the first week of a case series of three subjects ingesting alfalfa (30598). In a case series of 15 patients ingesting alfalfa, increased fecal volume and increased stool frequency was reported. Additional adverse effects included abdominal discomfort in two patients, diarrhea in two patients, loose stools in six patients, and intestinal gas in 13 patients (5816).

Hematologic ...Pancytopenia and splenomegaly were reported in a 59-year-old male who had been taking 80-160 grams of ground alfalfa seeds for up to six weeks at a time, for a five month period. Hematologic values and spleen size returned to normal when alfalfa was discontinued (381).

Other ...Alfalfa products, including sprouts, seeds, and tablets, have been found to be contaminated with Escherichia coli, Salmonella, and Listeria monocytogenes, which have caused documented infections (5600,30566,30568,30572,30569,30564,30604,30610,30563,30607) (30566,30564,30604,30610,30563,30607,30576).
Orally, alfalfa has been associated with the development of a lupus-like syndrome in animals and humans (30594,14828,14830,30602), as well as with possible exacerbations of lupus in patients with known systemic lupus erythematosus (SLE). These reactions may be associated with the amino acid L-canavanine (30594), which appears to be present in alfalfa seeds and sprouts, but not leaves, and therefore should not be present in alfalfa tablets manufactured from the leaves (30601). However, case reports have included individuals ingesting tablets. A lupus-like syndrome was described in four patients taking 12-24 alfalfa tablets per day. Symptoms included arthralgias, myalgias, and rash; positive antinuclear antibodies (ANA) arose anywhere from three weeks to seven months after initiating alfalfa therapy. Upon discontinuation of alfalfa tablets, all four patients became asymptomatic. In two patients, ANA levels normalized (14828). Two additional reports have documented possible exacerbation or induction of SLE associated with alfalfa use. One case involved a female with a 26-year history of SLE, who had been taking 15 tablets of alfalfa daily for nine months prior to an exacerbation. Because of the delay in onset of the exacerbation from the initiation of alfalfa therapy, causation cannot be clearly established (30575). In a different report, SLE and arthritis were found in multiple family members who had been taking a combination of vitamin E and alfalfa tablets for seven years (30602). It is not known what other environmental or genetic factors may have affected these individuals, and the association with alfalfa is unclear.

(Read more about ALFALFA)

General ...Orally, black pepper seems to be well tolerated when used in the amounts found in food or when taken as a medicine as a single dose. Topically and as aromatherapy, black pepper oil seems to be well tolerated.
Most Common Adverse Effects:
Orally: Burning aftertaste, dyspepsia, and reduced taste perception.
Inhalation: Cough.
Serious Adverse Effects (Rare):
Orally: Allergic reaction in sensitive individuals.

Gastrointestinal ...Orally, black pepper can cause a burning aftertaste (5619) and dyspepsia (38061). Single and repeated application of piperine, the active constituent in black pepper, to the tongue and oral cavity can decrease taste perception (29267). By intragastric route, black pepper 1.5 grams has been reported to cause gastrointestinal microbleeds (29164). It is not clear if such an effect would occur with oral administration.

Immunologic ...In one case report, a 17-month-old male developed hives, red eyes, facial swelling, and a severe cough following consumption of a sauce containing multiple ingredients. Allergen skin tests were positive to both black pepper and cayenne, which were found in the sauce (93947).

Ocular/Otic ...Topically, ground black pepper can cause redness of the eyes and swelling of the eyelids (5619).

Pulmonary/Respiratory ...When inhaled through the nose as an olfactory stimulant, black pepper oil has been reported to cause cough in one clinical trial (29162).

(Read more about BLACK PEPPER)

General ...Orally, capsicum is generally well tolerated in amounts typically found in food or when the extract is used in doses of up to 200 mg daily. Topically and intranasally, capsaicin, a constituent of capsicum, is generally well tolerated.
Most Common Adverse Effects:
Orally: Belching, bloating, burning, diarrhea, dyspepsia, gas, headache, mild constipation, nausea, rhinorrhea, skin flushing, and sweating.
Serious Adverse Effects (Rare):
Orally: Cases of myocardial infarction and hypertensive crisis have been reported.

Cardiovascular ...Orally, palpitation was reported in one clinical trial (105196).
One case of myocardial infarction has been reported in a 41-year-old male without cardiovascular risk factors; the event was attributed to the use of an oral capsicum pepper pill that the patient had been taking for weight loss (40768). Another case of coronary vasospasm and acute myocardial infarction has been reported for a healthy 29-year-old male; the event was attributed to the use of a topical capsicum-containing patch that the patient had been applying to the middle of the back for 6 days (40658). Two cases of arterial hypertensive crisis have been reported for individuals who ingested a large amount of peppers and chili peppers the day before. One of the patients also had an acute myocardial infarction, and the other had high levels of thyroid stimulating hormone (40569,40606).

Dermatologic ...Orally, capsicum or its constituent capsaicin may cause urticaria and skin wheals in rare cases (96457,105203).
Topically, capsicum can cause a prickling sensation, itching, pain, burning, edema, stinging, irritation, rash, and erythema. About 1 in 10 patients who use capsaicin topically discontinue treatment because of adverse effects. These effects seem to occur more often with topical formulations containing higher concentrations of capsaicin, the active constituent of capsicum. Side effects tend to diminish with continued use (12401,15260,15261,40358,40439,40483,40547,40676,40682,40719)(40784,40847,92979,92983,92984,96453,105193,105197,105202,111514). In one case, application of a capsaicin 8% patch (Qutenza) for 60 minutes caused a second-degree burn, characterized by burning, erythema, severe pain, and blistering at the administration site. The burn was treated with topical corticosteroids, but 9 months later neuropathic pain persisted, resulting in limited mobility. It is unclear whether the mobility sequalae were caused by topical capsaicin or the patient's pre-existing neurological disorders (111514). Skin contact with fresh capsicum fruit can also cause irritation or contact dermatitis (12408).
Intranasally, capsaicin can cause nasal burning and pain in most patients. It also often causes lacrimation, sneezing, and excessive nasal secretion; however, these side effects appear to diminish with repeat applications (14323,14329,14358). In some cases, the burning sensation disappears after 5-8 applications (14351,14358). In some cases, patients are pretreated with intranasal lidocaine to decrease the pain of intranasal capsaicin treatment. However, even with lidocaine pretreatment, patients seem to experience significant pain (14324).

Gastrointestinal ...Orally, capsicum can cause upper abdominal discomfort, including irritation, fullness, dyspepsia, gas, bloating, nausea, epigastric pain and burning, anal burning, diarrhea, mild constipation, and belching (12403,12410,40338,40427,40456,40503,40560,40584,40605,40665)(40718,40725,40745,40808,40828,96456,96457,105194,105196). There is a case report of a 3-year-old female who experienced a burning and swollen mouth and lips after touching the arm of a parent that had been treated with a capsaicin patch and then placing the fingers in the mouth (105199). Excessive amounts of capsaicin can lead to gastroenteritis and hepatic necrosis (12404). In a case report, a 40-year-old male with diabetes consumed white wine daily and chewed cayenne which was thought to result in black teeth stains and loss of enamel (40809). Some preliminary research links ingestion of capsaicin with stomach and gallbladder cancer; however the link may be due to contamination of capsaicin products with carcinogens (40771).
Topically, capsaicin can cause diarrhea and vomiting (105202).

Immunologic ...In a case report, a 34-year-old female had anaphylaxis involving difficulty breathing and stupor and also urticaria after consuming a red bell pepper, which is in the capsicum genus. The causal chemical was theorized to be 1,3-beta-glucanase (92978). In another case report, a 33-year-old female experienced angioedema, difficulty breathing and swallowing, and urticaria after ingesting raw green and red peppers (92982).

Neurologic/CNS ...Orally, capsicum can cause sweating and flushing of the head and neck, lacrimation, headache, faintness, and rhinorrhea (7005,12410,105196,105203). Topically, applying capsaicin can cause headache (96450,105202). Injection of capsaicin into the intermetatarsal space has also been associated with headache (96454).

Ocular/Otic ...Topically, capsicum can be extremely irritating to the eyes and mucous membranes. Capsicum oleoresin, an oily extract in pepper self-defense sprays, causes intense eye pain. It can also cause erythema, blepharospasm, tearing, shortness of breath, and blurred vision. In rare cases, corneal abrasions have occurred (12408,12409,40345,40348,40383,40720,40857).
Inhalation of capsicum can cause eye irritation, and allergic alveolitis (5885). In a case report, a 38-year-old female had acute anterior uveitis that developed about 12 hours after using a specific patch (Isola Capsicum N Plus) that contained capsaicin 1.5 mg per patch and methyl salicylate 132 mg per patch for neck pain. The uveitis was controlled with topical steroids and did not recur (92977).

Oncologic ...Population research suggests that moderate to high intake of capsaicin, the active constituent of capsicum, is associated with an increased risk of gastric cancer, while low intake is associated with a decreased risk. It is not clear from the study what amount of capsaicin is considered high versus low intake (92988). Additionally, some research suggests that any link may be due to contamination of capsaicin products with carcinogens (40771).

Pulmonary/Respiratory ...Orally, difficulty breathing was reported in a clinical trial (105196).
Topically, nasopharyngitis related to the use of a cream containing capsaicin has been reported (105202).
Inhalation of capsicum and exposure to capsicum oleoresin spray can cause cough, dyspnea, pain in the nasal passages, sneezing, rhinitis, and nasal congestion (5885,15016,40522,40546,40647). In rare cases, inhalation of the capsicum oleoresin or pepper spray has caused cyanosis, apnea, respiratory arrest and death in people. Death was caused by asphyxiation probably due to acute laryngeal edema and bronchoconstriction from inhalation of the capsicum oleoresin spray (40546,40672,40837,40879).
In a case report, a 47-year-old female who was exposed to capsaicin gas for more than 20 minutes experienced acute cough, shortness of breath, short-term chest pain, wheezing, and difficulty breathing for months afterwards (92980). In rare cases, exposure to capsicum oleoresin spray resulted in apnea, pulmonary injury, cyanosis, and even respiratory arrest (40383,40546).

(Read more about CAPSICUM)

General ...Orally, fenugreek seed is generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, bloating, diarrhea, dyspepsia, flatulence, hypoglycemia, and nausea.
Serious Adverse Effects (Rare):
All ROA: Severe allergic reactions including angioedema, bronchospasm, and shock.

Endocrine ...Orally, large doses of fenugreek seed, 100 grams daily of defatted powder, have caused hypoglycemia (164,96068).

Gastrointestinal ...Orally, fenugreek seed can cause mild gastrointestinal symptoms, such as diarrhea, dyspepsia, abdominal distention and pain, nausea, and flatulence, especially when taken on an empty stomach (622,12534,18349,93421,96065,96068,105016).

Immunologic ...Fenugreek can cause allergic reactions when used orally and topically, and when the powder is inhaled (719,96068). Orally, fenugreek has caused bronchospasm, diarrhea, and itching, and skin reactions severe enough to require intravenous human immunoglobulin (96068). Topically, fenugreek paste has resulted in facial swelling, wheezing, and numbness around the head (719,96068). When used both orally and topically by a single individual, asthma and rhinitis occurred (96068). Inhalation of fenugreek powder has resulted in fainting, sneezing, runny nose, and eye tearing (719,96068).

Neurologic/CNS ...Orally, loss of consciousness has occurred in a 5 week-old infant drinking tea made from fenugreek (9782). Dizziness and headaches have been reported in clinical research of fenugreek extract (49551,93419). However, these events are rare.

Renal ...Orally, fenugreek aqueous see extract may increase the frequency of micturition, although this even appears to be rare (49551).

Other ...Consumption of fenugreek during pregnancy, immediately prior to delivery, may cause the neonate to have an unusual body odor, which may be confused with maple syrup urine disease. It does not appear to cause long-term sequelae (9781). This unusual body odor may also occur in children drinking fenugreek tea. A case of a specific urine and sweat smell following oral fenugreek extract use has been reported for a patient in one clinical trial (18349).
In 2011, outbreaks of enteroaggregative hemorrhagic Escherichia coli (EATEC) O104:H4 infection occurred in Germany and Spain. Epidemiological studies linked the outbreaks to fenugreek seeds that had been imported from Africa. However, laboratory analyses were unable to isolate the causative strain of bacteria from fenugreek seed samples (49776,49777,49781,90114).

(Read more about FENUGREEK)

General ...Orally, licorice is generally well tolerated when used in amounts commonly found in foods. It seems to be well tolerated when licorice products that do not contain glycyrrhizin (deglycyrrhizinated licorice) are used orally and appropriately for medicinal purposes or when used topically, short-term.
Most Common Adverse Effects:
Orally: Headache, nausea, and vomiting.
Topically: Contact dermatitis.
Intravenously: Diarrhea, itching, nausea, and rash.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about acute renal failure, cardiac arrest, cardiac arrhythmias, hypertension, hypokalemia, muscle weakness, paralysis, pseudohyperaldosteronism, and seizure associated with long-term use or large amounts of licorice containing glycyrrhizin.

Cardiovascular ...Orally, excessive licorice ingestion can lead to pseudohyperaldosteronism, which can precipitate cardiovascular complications such as hypertension and hypertensive crisis, ventricular fibrillation or tachycardia, sinus pause, and cardiac arrest. These effects are due to the licorice constituent glycyrrhizin and usually occur when 20-30 grams or more of licorice product is consumed daily for several weeks (781,15590,15592,15594,15596,15597,15599,15600,16835,97213) (104563,108574,108576,110305,112234). In one case report, an 89-year-old female taking an herbal medicine containing licorice experienced a fatal arrhythmia secondary to licorice-induced hypokalemia. The patient presented to the hospital with recurrent syncope, weakness, and fatigue for 5 days after taking an herbal medicine containing licorice for 2 months. Upon admission to the hospital, the patient developed seizures, QT prolongation, and ventricular arrhythmia requiring multiple defibrillations. Laboratory tests confirmed hypokalemia and pseudohyperaldosteronism (112234).
However, people with cardiovascular or kidney conditions may be more sensitive, so these adverse events may occur with doses as low as 5 grams of licorice product or glycyrrhizin 100 mg daily (15589,15593,15598,15600,59726). A case report in a 54-year-old male suggests that malnutrition might increase the risk of severe adverse effects with excessive licorice consumption. This patient presented to the emergency room with cardiac arrest and ventricular fibrillation after excessive daily consumption of licorice for about 3 weeks. This caused pseudohyperaldosteronism and then hypokalemia, leading to cardiovascular manifestations. In spite of resuscitative treatment, the patient progressed to kidney failure, refused dialysis, and died shortly thereafter (103791).

Dermatologic ...There have been reports of contact allergy, resulting in an itchy reddish eruption, occurring in patients that applied cosmetic products containing oil-soluble licorice extracts (59912). There have also been at least 3 cases of allergic contact dermatitis reported with the topical application of glycyrrhizin-containing products to damaged skin. In one case report, a 31-year-old female with acne presented with a 2-year history of pruritic erythematous-scaly plaques located predominantly on the face and neck after the use of a cosmetic product containing licorice root extract 1%. The patient had a positive skin patch test to licorice root extract, leading the clinicians to hypothesize that the use of benzoyl peroxide, a strong irritant, might have sensitized the patient to licorice (108578). Burning sensation, itching, redness, and scaling were reported rarely in patients applying a combination of licorice, calendula, and snail secretion filtrate to the face. The specific role of licorice is unclear (110322).
In rare cases, the glycyrrhizin constituent of licorice has caused rash and itching when administered intravenously (59712).

Endocrine ...Orally, excessive licorice ingestion can cause a syndrome of apparent mineralocorticoid excess, or pseudohyperaldosteronism, with sodium and water retention, increased urinary potassium loss, hypokalemia, and metabolic alkalosis due to its glycyrrhizin content (781,10619,15591,15592,15593,15594,15595,15596,15597,15598)(15600,16057,16835,25659,25660,25673,25719,26439,59818,59822)(59832,59864,91722,104563,108568,108574,110305,112234). These metabolic abnormalities can lead to hypertension, edema, EKG changes, fatigue, syncope, arrhythmias, cardiac arrest, headache, lethargy, muscle weakness, dropped head syndrome (DHS), rhabdomyolysis, myoglobinuria, paralysis, encephalopathy, respiratory impairment, hyperparathyroidism, and acute kidney failure (10393,10619,15589,15590,15593,15594,15596,15597,15599)(15600,16057,16835,25660,25673,25719,26439,31562,59709,59716)(59720,59740,59787,59820,59826,59882,59889,59900,91722,97214,100522) (104563,108576,108577). These effects are most likely to occur when 20-30 grams of licorice products containing glycyrrhizin 400 mg or more is consumed daily for several weeks (781,15590,15592,15594,15596,15597,15599,15600,16835,108574). However, some people may be more sensitive, especially those with hypertension, diabetes, heart problems, or kidney problems (15589,15593,15598,15600,59726,108576,108577) and even low or moderate consumption of licorice may cause hypertensive crisis or hypertension in normotensive individuals (1372,97213). The use of certain medications with licorice may also increase the risk of these adverse effects (108568,108577). One case report determined that the use of large doses of licorice in an elderly female stabilized on fludrocortisone precipitated hypokalemia and hypertension, requiring inpatient treatment (108568). Another case report describes severe hypokalemia necessitating intensive care treatment due to co-ingestion of an oral glycyrrhizin-specific product and hydrochlorothiazide for 1 month (108577). Glycyrrhetinic acid has a long half-life, a large volume of distribution, and extensive enterohepatic recirculation. Therefore, it may take 1-2 weeks before hypokalemia resolves (781,15595,15596,15597,15600). Normalization of the renin-aldosterone axis and blood pressure can take up to several months (781,15595,108568). Treatment typically includes the discontinuation of licorice, oral and intravenous potassium supplementation, and short-term use of aldosterone antagonists, such as spironolactone (108574,108577).
Chewing tobacco flavored with licorice has also been associated with toxicity. Chewing licorice-flavored tobacco, drinking licorice tea, or ingesting large amounts of black licorice flavored jelly beans or lozenges has been associated with hypertension and suppressed renin and aldosterone levels (12671,12837,97214,97215,97217,108574). One case report suggests that taking a combination product containing about 100 mg of licorice and other ingredients (Jintan, Morishita Jintan Co.) for many decades may be associated with hypoaldosteronism, even up to 5 months after discontinuation of the product (100522). In another case report, licorice ingestion led to hyperprolactinemia in a female (59901). Licorice-associated hypercalcemia has also been noted in a case report (59766).

Gastrointestinal ...Nausea and vomiting have been reported rarely following oral use of deglycyrrhizinated licorice (25694,59871). Intravenously, the glycyrrhizin constituent of licorice has rarely caused gastric discomfort, diarrhea, or nausea (59712,59915).

Immunologic ...There have been reports of contact allergy, resulting in an itchy reddish eruption, occurring in patients that applied cosmetic products containing oil-soluble licorice extracts (59912). There have also been at least 3 cases of allergic contact dermatitis reported with the topical application of glycyrrhizin-containing products to damaged skin. In one case report, a 31-year-old female with acne presented with a 2-year history of pruritic erythematous-scaly plaques located predominantly on the face and neck after the use of a cosmetic product containing licorice root extract 1%. The patient had a positive skin patch test to licorice root extract, leading the clinicians to hypothesize that the use of benzoyl peroxide, a strong irritant, might have sensitized the patient to licorice (108578).

Musculoskeletal ...In a case report, excessive glycyrrhizin-containing licorice consumption led to water retention and was thought to trigger neuropathy and carpal tunnel syndrome (59791).

Neurologic/CNS ...Orally, licorice containing larger amounts of glycyrrhizin may cause headaches. A healthy woman taking glycyrrhizin 380 mg daily for 2 weeks experienced a headache (59892). Intravenously, the glycyrrhizin constituent of licorice has rarely caused headaches or fatigue (59721). In a case report, licorice candy ingestion was associated with posterior reversible encephalopathy syndrome accompanied by a tonic-clonic seizure (97218).

Ocular/Otic ...Orally, consuming glycyrrhizin-containing licorice 114-909 grams has been associated with transient visual loss (59714).

Pulmonary/Respiratory ...Orally, large amounts of licorice might lead to pulmonary edema. In one case report, a 64-year old male consumed 1020 grams of black licorice (Hershey Twizzlers) containing glycyrrhizin 3.6 grams over 3 days, which resulted in pulmonary edema secondary to pseudohyperaldosteronism (31561). Intravenously, the glycyrrhizin constituent of licorice has caused cold or flu-like symptoms, although these events are not common (59712,59721).

(Read more about LICORICE)

General ...Information regarding the adverse effects of mullein is limited. A thorough evaluation of safety outcomes has not been conducted.

Dermatologic ...Two case reports have described dermatitis, with positive patch tests, after topical exposure to the whole plant, or by occupational inhalation of plant dust (92839,97316). In the case of topical exposure, the patient also had positive patch tests to other plants.

(Read more about MULLEIN)

General ...Orally, intravenously, and as an inhalation, N-acetyl cysteine is generally well-tolerated when used in typical doses. Most adverse effects to N-acetyl cysteine occur when single doses of greater than 9 grams are used or when a regimen of greater than 30 grams daily is followed.
Most Common Adverse Effects:
Orally: Diarrhea, dry mouth, dyspepsia, heartburn, loss of appetite, nausea, and vomiting.
Intravenously: Skin rash and hypersensitivity reactions.
Inhaled: Bronchospasm, cough, epigastric pain, throat irritation, and wheezing.
Serious Adverse Effects (Rare):
Orally: Chest tightness, hemoptysis, and palpitations have been reported.
Intravenously: Anaphylaxis, angina, dystonic reactions, tachycardia, and transient sinus bradycardia have been reported.

Cardiovascular ...Intravenously, N-acetyl cysteine has been reported to significantly increase systolic and diastolic blood pressure after exposure to nitroglycerin when compared with placebo (2280). Tachycardia, chest pain, angina, and transient sinus bradycardia have been rarely reported after administration of intravenous N-acetyl cysteine (2280,7872,64658).
Intratracheally, infants receiving 5% N-acetyl cysteine every four hours for chronic lung disease have developed bradycardia (64490).
Orally, palpitations and chest tightness have been reported rarely in clinical research evaluating oral N-acetyl cysteine at doses up to 600 mg twice daily (64675,64717,64762).

Dermatologic ...Orally, N-acetyl cysteine may cause hives (64713,64739,64813), flushing (2260,64715), and edema (64714). Rash has also been reported (64510,64715,64717,102656). In one study, flushing was reported in 2% of patients receiving 600 mg of N-acetyl cysteine orally twice daily for six months (2260).
Intravenously, N-acetyl cysteine may cause rash, and the occurrence seems to be more common than with oral use (2254,64492,64562,64658,64759,64794). Hives (2280,64794), facial edema (2280), flushing (64412), and pruritus (64658,64763) have also been reported. In a small case series of 10 healthy male patients receiving 150 mg/kg of intravenous N-acetyl cysteine for muscle fatigue, erythema was experienced 30 minutes after infusion. Other side effects reported by these patients include facial erythema, palmar erythema, and sweating (64763). In other clinical research, three patients developed an erythematous flare at the sites of previous venipunctures after receiving 5.5 gm/m2 of N-acetyl cysteine with doxorubicin therapy (64712). Pain, inflammation, and excoriation of the skin have been reported after a 20% N-acetyl cysteine solution leaked from the catheter in one patient (64726).

Gastrointestinal ...Orally, gastrointestinal complaints are the most common adverse effects reported with N-acetyl cysteine. These include heartburn (64608,64715,64717,64738,64739,102666), dyspepsia (1710,64715,64717,64724,64738), and epigastric pain (2260,10429,64715,64717). In one case report, esophagitis related to ulcerations occurred following intake of N-acetyl cysteine while in the supine position with inadequate water (102655). Other common side effects include loss of appetite (64715,64812), flatulence (2256,64510), diarrhea (64713,64715,97049), constipation (64715), dry mouth (64715,64724), nausea (7868,11430,64715,64724,64738,64812,97049), vomiting (64717,64724,64715,97049), gastric upset (64510,64545,97045,97049), acid reflux (108450), changes in bowel habits (108450), and intolerance to taste and odor (64510,64545). N-acetyl cysteine's unpleasant odor makes it difficult for some patients to take orally. Using a straw to drink N-acetyl cysteine solutions can improve tolerability. Additionally, placement of a nasogastric or duodenal tube and administration of metoclopramide or ondansetron can be helpful for patients unable to tolerate oral N-acetyl cysteine (17).
Intravenously, N-acetyl cysteine may cause diarrhea (64712), dyspepsia, nausea, vomiting (64763), mild gastrointestinal upset (102657), and metallic taste (64763).
When inhaled, N-acetyl cysteine may cause epigastric pain and throat irritation (64703,64707,64674).

Genitourinary ...Orally, dysuria was reported in 2% of patients receiving 600 mg of N-acetyl cysteine twice daily for 6 months in one clinical trial (2260).

Hematologic ...In general, hematologic adverse reactions are reported more frequently with intravenous N-acetyl cysteine compared with oral use. In surgical patients, decreased prothrombin time (1341,64511), prolonged coagulation time (64511), increased blood loss (64511,64644), and decreased platelet aggregation (64511) have been reported after administration of IV N-acetyl cysteine. In one clinical trial, six healthy patients were administered a loading dose of IV N-acetyl cysteine 10 mg/kg followed by 10 mg/kg per hour for 32 hours. All patients experienced a decrease in prothrombin time by 30% to 40%. The decrease prothrombin time (25.4 sec to 20.6 sec) reached a steady state after 16 hours (1341). In a clinical trial evaluating patients with acute myocardial infarction, hemorrhage occurred in three patients taking intravenous N-acetyl cysteine 10 mg/min, heparin (per study protocol), and aspirin (7872). Two pediatric patients receiving intravenous N-acetyl cysteine (loading dose: 140 mg/kg followed by 70 mg/kg) experienced episodes of coagulopathy; however, patients were being treated for acetaminophen overdose (64794).
Hemoptysis was reported in six patients receiving 200 mg of N-acetyl cysteine orally twice daily for 6 months for treatment of chronic bronchitis (64739).

Immunologic ...Orally, anaphylaxis to N-acetyl cysteine has been rarely reported (64794). However, anaphylactic reactions to intravenous N-acetyl cysteine appear to be more common (1716,64412,64449,64628,64710,64711,64721,64786,64789).
Anaphylactic reactions to N-acetyl cysteine have involved rash, angioedema, hypotension, and bronchospasm (64449,64711,64720). The mechanism of this reaction is unclear, but some data suggest it is not an immunologic hypersensitivity reaction but rather an acute toxic effect of N-acetyl cysteine (64786,64641,64720). Management guidelines for the treatment of anaphylactoid reactions to intravenous N-acetyl cysteine have been published. In most cases, treatment is not required or treatment with diphenhydramine or salbutamol is sufficient to continue or restart N-acetyl cysteine infusion. Antihistamines are useful in controlling and preventing recurrence of anaphylactoid symptoms (1716).

Musculoskeletal ...In one clinical trial, joint pain was reported in more than 15% of patients receiving oral N-acetyl cysteine (64608). In other research, one patient experienced pain in the legs while taking 600 mg of N-acetyl cysteine twice daily for the treatment of chronic bronchitis (64762).

Neurologic/CNS ...Orally, headache has been frequently reported with N-acetyl cysteine in clinical research (7873,11430,64510,64608,64672,64713,64715,64724,64762). Other less common adverse effects reported in patients taking oral N-acetyl cysteine at a total daily dose of 600-1200 mg include dizziness (64715,64717,64724,64762), tiredness (64675,64717), vivid dreams (102666), disorientation, and inability to concentrate (64673). One pediatric patient receiving oral N-acetyl cysteine (loading dose: 140 mg/kg followed by 70 mg/kg) experienced encephalopathy (64794).
Intravenously, N-acetyl cysteine has been associated with rare neurologic adverse reactions , including headache (7872), lightheadedness (64763), and dystonic reactions (64794). In a previously healthy 2-year-old female, status epilepticus occurred during intravenous N-acetyl cysteine therapy for paracetamol ingestion (64781). Increased deterioration in bulbar function in patients with amyotrophic lateral sclerosis has also been reported with IV N-acetyl cysteine (2254).

Ocular/Otic ...While rare, blurred vision has been reported in research on oral N-acetyl cysteine (64715). Additionally, in a previously healthy 2-year-old female, status epilepticus followed by cortical blindness occurred during intravenous N-acetyl cysteine therapy for paracetamol ingestion. In this case, vision was almost completely recovered 18-months later (64781).

Psychiatric ...Intravenously, dysphoria was experienced 30 minutes after infusion of N-acetyl cysteine in 8 of 10 healthy males assessed in one clinical study (64763).

Pulmonary/Respiratory ...Respiratory adverse reactions to N-acetyl cysteine are most commonly reported with inhalable dosage forms. These include wheezing (64455,64707), bronchospasm (64455,64699), and cough (64455,64456,64703,64811). While less frequent, wheezing (64675), bronchospasm (64675), increased sputum production (7868), cough (7868,64510), decreased peak flow (64510), dyspnea (64714), and cold symptoms (64510) have been reported with oral N-acetyl cysteine in clinical research. A few cases of wheezing (64718,64719), cough (64763), and bronchospasm (64658) have also been reported with intravenous N-acetyl cysteine. Additionally, respiratory arrest has been reported in one case where a 16 year-old female was being treated for acetaminophen toxicity with intravenous N-acetyl cysteine (64450).
Two premature infants receiving 5% N-acetyl cysteine via intratracheal instillation for the treatment of chronic lung disease had an increased frequency of cyanotic spells (64490).

Other ...Injection site reactions, including burning and phlebitis, have been reported in patients receiving IV N-acetyl cysteine (1341,64763). Fever associated with IV N-acetyl cysteine was reported in one patient during clinical research (64759).

(Read more about N-ACETYL CYSTEINE (NAC))

General ...Orally, onion is well tolerated. Topically, onion is generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, heartburn.
Topically: Eczema, irritation.
Serious Adverse Effects (Rare):
All ROAs: Anaphylaxis in sensitive individuals.

Dermatologic ...Topically, frequent contact with onions can result in hand eczema, pemphigus, sensitization, and irritation (18,5004,51303,67066,67093).

Gastrointestinal ...The consumption of large quantities of onions or onion powder can cause stomach distress or heartburn (18,95155,104772). Stomach distress from onion powder appears to be transient (104772). In one case report, consumption of raw onions led to esophageal spasm (66841).

Immunologic ...Allergy to onion is rare, although there are reports of symptoms to both oral and topical exposure (41752,101743). In one case, oral exposure or the aroma of onions caused the sensation of throat closing in an allergic woman (88404). In a 35-year-old man, cooked onion ingestion triggered anaphylaxis (101742). In another case, the smell of onion was identified as a trigger for migraines in a 32-year-old female. Because the patient had a positive allergy skin test for onion, allergenic or immunogenic mechanisms were considered to be the origin of the migraines (88404).

Ocular/Otic ...Exposure to onion aroma can cause excessive tearing (67049).

(Read more about ONION)

General ...Orally and topically, PABA is generally well tolerated.
Most Common Adverse Effects:
Orally: Anorexia, dyspepsia, fever, nausea, rash, vomiting.
Topically: Dermatitis, paradoxical photosensitivity.
Serious Adverse Effects (Rare):
Orally: Hepatotoxicity.

Dermatologic ...Topically, PABA can cause contact dermatitis and sometimes paradoxical photosensitivity (272).

Gastrointestinal ...Orally, the most commonly reported side effects of PABA are diarrhea, nausea, vomiting, anorexia, dyspepsia, fever, and rash (1074). PABA should be discontinued if adverse effects prevent the patient from eating (10). In one report, up to 25% of patients discontinued PABA due to intolerance of side effects (1074).

Hematologic ...High dose PABA (up to 48 grams per day) can cause decreased white blood count below 4000 mm3 in approximately 30% of patients (1061).

Hepatic ...Liver toxicity, including fatal hepatitis has been reported in patients taking PABA in high doses (12-48 grams per day) (1061,1094). In one case, 12 grams per day for 2 months caused liver toxicity (1094). Increased liver function tests from PABA have also been noted (1084), and jaundice was reported in one case of treatment with PABA (68049). Despite these reports, a study reviewing the charts of 274 patients with scleroderma who were taking the potassium salt form of PABA as treatment found no evidence of hepatotoxicity (1065).

Immunologic ...Orally, PABA can cause allergic reactions including fever and skin rash (1074).

Neurologic/CNS ...Orally, PABA may cause headaches, which resolve upon discontinuation of treatment (1074).

Other ...Death has been reported in 3 children treated with 24 grams of PABA per day for rheumatic fever or arthritis. At autopsy, all had fatty changes in the liver, kidney, and myocardium (1061). Topical PABA and its derivatives have a tendency to discolor clothing due to a photo-oxidative reaction (68025).

(Read more about PARA-AMINOBENZOIC ACID (PABA))

General ...Orally, pleurisy root can cause gastrointestinal irritation, nausea, and vomiting (19). When consumed in large quantities, pleurisy root may cause digitalis-like poisoning symptoms (18). Acute digitalis poisoning symptoms include gastrointestinal upset, contracted pupils, blurred vision, strong slow pulse, nausea, vomiting, dizziness, excessive urination, fatigue, muscle weakness and tremors, stupor, confusion, convulsions, atrial arrhythmias, bradycardia, AV block, cardiovascular shock, and death (6,159,501).
Topically, pleurisy root may cause dermatitis (19).

Cardiovascular ...Orally, consuming large quantities of pleurisy root may cause digitalis-like poisoning symptoms (18). Acute digitalis poisoning symptoms include strong slow pulse, atrial arrhythmias, bradycardia, AV block, cardiovascular shock, and death (6,159,501).

Dermatologic ...Topically, pleurisy root may cause dermatitis (19).

Gastrointestinal ...Orally, pleurisy root can cause gastrointestinal irritation, nausea, and vomiting (19). When consumed in large quantities, pleurisy root may cause digitalis-like poisoning symptoms (18). Acute digitalis poisoning symptoms include nausea, vomiting, and gastrointestinal upset (6,159,501).

Neurologic/CNS ...Orally, consuming large quantities of pleurisy root may cause digitalis-like poisoning symptoms (18). Acute digitalis poisoning symptoms include dizziness, stupor, confusion, convulsions, and fatigue (6,159,501).

Ocular/Otic ...Orally, consuming large quantities of pleurisy root may cause digitalis-like poisoning symptoms (18). Acute digitalis poisoning symptoms include contracted pupils and blurred vision (6,159,501).

Renal ...Orally, consuming large quantities of pleurisy root may cause digitalis-like poisoning symptoms (18). Acute digitalis poisoning symptoms include excessive urination (6,159,501).

(Read more about PLEURISY ROOT)

General ...There is currently a limited amount of information available on the adverse effects of skullcap.
Most Common Adverse Effects:
Orally: Cognitive impairment, digestive disturbances, sedation.

Gastrointestinal ...Orally, mild digestive disturbances were reported in around 9% of patients taking skullcap 350 mg three times daily for 2 weeks (91690).

Hepatic ...There are four reports of hepatotoxicity associated with products thought to contain skullcap. However, it is uncertain whether the products actually contained skullcap. It is thought that the products might have been contaminated with an adulterant such as germander (515), which is known to cause liver damage.

Neurologic/CNS ...A single skullcap extract dose of 100 mg does not seem to have adverse CNS effects. However, a higher dose of 200 mg might cause sedation and cognitive impairment (12216). One patient taking skullcap 350 mg three times daily for 2 weeks reported vivid dreams (91690). It is unclear if this event was associated with skullcap.

(Read more about SKULLCAP)

General ...Orally, thyme is well tolerated when used in food and seems to be well tolerated when used medicinally. Topically, thyme seems to be generally well tolerated.
Most Common Adverse Effects:
Orally: Allergic reactions, diarrhea, dizziness, headache, heartburn, nausea, or vomiting.
Topically: Contact dermatitis and skin irritation.

Dermatologic ...Topically, thyme, thyme oil, or the constituent thymol can cause contact dermatitis and skin irritation (13463,78252,78362,78384,77982,78154,78310,78313,78384). In one study of 100 patients with contact allergies, 5% were attributed to thyme oil as an allergen contained in wound dressings (78362). Toothpastes containing thymol have been associated with cheilitis and glossitis (13463).

Gastrointestinal ...Orally, thyme and thyme oil may cause heartburn, nausea, vomiting, stomach upset, or diarrhea (13557,94033). In a clinical study, two patients using extracts of thyme herb and ivy leaves experienced temporary stomach ache and mild nausea (78181).
Intravaginally, cream containing thyme and garlic has been associated with reports of nausea and vomiting in one clinical study (88387). It is not clear if these adverse effects were associated with thyme, garlic, or the combination.

Genitourinary ...Intravaginally, cream containing thyme and garlic has been associated with reports of vaginal dryness and vaginal irritation in one clinical study (88387). It is not clear if these adverse effects were associated with thyme, garlic, or the combination.

Immunologic ...Orally, thyme can cause allergic reactions; however, this is uncommon (13463). Allergic reactions to thyme might be more common in people who are also allergic to oregano and other Lamiaceae species (3808).

Neurologic/CNS ...Orally, thyme may case headache or dizziness (94033).

Pulmonary/Respiratory ...By inhalation, occupational exposure to thyme dust can cause acute airway obstruction (783,13463,13464,77982,78098).

(Read more about THYME)