Peppermint + Oregano Oil Complex by Natural Factors

POSSIBLY EFFECTIVE

• Dyspepsia. Oral caraway in combination with peppermint and possibly other ingredients, seems to reduce symptoms of dyspepsia. It is unclear if oral caraway alone is beneficial. Details: Several small, low-quality clinical studies and a meta-analysis of this research show that taking proprietary combinations of caraway oil 50 mg and peppermint oil 90 mg (Enteroplant or Menthacarin, Dr Willmar Schwabe GmbH & Co.), 1-3 times daily for 4 weeks, improves quality of life and reduces symptoms of dyspepsia, including feelings of fullness, pain, and mild gastrointestinal (GI) spasms, when compared with placebo (6740,6741,10075,96344,102600). A meta-analysis of three of these clinical studies shows that taking this combination product 2-3 times daily for 4 weeks modestly reduces abdominal pain when compared with placebo (110091). This combination appears to be comparable to cisapride for relieving dyspepsia (6740,6741,10075). It also improves postprandial distress syndrome and epigastric pain syndrome, two subtypes of dyspepsia, when compared with placebo (96344). Another small clinical study in patients with functional dyspepsia shows that taking a combination of caraway oil 50 mg and L-menthol 41.4 mg (equivalent to 100 mg peppermint oil), in a microsphere formulation that releases the oils in the duodenum (FDgard, IM HealthScience LLC), twice daily for 28 days reduces symptoms of postprandial distress syndrome within 24 hours and reduces severe symptoms of epigastric pain syndrome at 28 days when compared with placebo. However, when all patients with functional dyspepsia are considered, symptom scores are not significantly different than placebo at 28 days (103161). Another specific combination product containing caraway, peppermint leaf, clown's mustard plant, German chamomile, licorice root, milk thistle, angelica, celandine, and lemon balm (Iberogast, Steigerwald Arzneimittelwerk GmbH) has also been evaluated in patients with dyspepsia, with promising results (7049). A meta-analysis of three small clinical studies using this combination product shows that taking 1 mL three times daily for 4 weeks reduces severity of acid reflux, epigastric pain, cramping, nausea, and vomiting when compared with placebo (13089). Other clinical research in patients with dyspepsia shows that taking a similar combination product (STW 5-II, Steigerwald Arzneimittelwerk GmbH) that does not contain milk thistle, angelica, or celandine as 1 mL three times daily for up to 8 weeks eliminates gastrointestinal symptoms in 40% more patients when compared with placebo (12724). It is unclear if these findings are due to caraway, other ingredients, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Amenorrhea. Although there has been interest in using oral caraway for amenorrhea, there is insufficient reliable information about the clinical effects of caraway for this purpose.
• Asthma. Oral caraway has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with allergic asthma shows that drinking one cup of tea containing caraway along with anise, black seed, saffron, cardamom, chamomile, fennel, and licorice twice daily for 6 months reduces sleep discomfort, cough frequency, and cough intensity when compared with placebo (19056). It is unclear if these findings are due to caraway, other ingredients, or the combination.
• Constipation. Although there has been interest in using oral caraway for constipation, there is insufficient reliable information about the clinical effects of caraway for this purpose.
• Dysmenorrhea. Although there has been interest in using oral caraway for dysmenorrhea, there is insufficient reliable information about the clinical effects of caraway for this purpose.
• Flatulence. Although there has been interest in using oral caraway for flatulence, there is insufficient reliable information about the clinical effects of caraway for this purpose.
• Irritable bowel syndrome (IBS). It is unclear if topical caraway oil is beneficial in patients with IBS. Details: A small, open-label study in patients with IBS shows that applying a heated poultice of caraway oil 2% to the abdomen for 20-30 minutes at least once daily for 3 weeks modestly improves the severity of IBS symptoms when compared with applying a nonheated, olive oil poultice. However, the improvement may not be clinically meaningful. Also, the heated caraway oil poultice is not more effective than a heated olive oil poultice. This suggests that any possible benefit might relate to the application of heat rather than caraway oil (94085).
• Obesity. It is unclear if oral caraway seed extract is beneficial in patients with obesity. Details: A small clinical study in physically active overweight and obese females shows that taking 30 mL of an aqueous extract providing about 3 grams of caraway seed once daily prior to lunch for 3 months decreases body weight by about 2 kg, body mass index by 0.84 kg/m², percent body fat by 0.7%, and waist circumference by 6 cm, and increases percent muscle mass by 0.19%, when compared to baseline (94088). These improvements are significant when compared with placebo; however, they might not be considered clinically meaningful. Taking caraway seed aqueous extract does not appear to improve blood pressure or lipid levels in these patients (94086). More evidence is needed to rate caraway for these uses.

(Read more about CARAWAY)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there has been interest in using topical oregano oil for acne, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Asthma. Although there has been interest in using oral oregano for asthma, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Bronchitis. Although there has been interest in using oral oregano for bronchitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Canker sores. Although there has been interest in using topical oregano oil for canker sores, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Cough. Although there has been interest in using oral oregano for cough, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Dandruff. Although there has been interest in using topical oregano oil for dandruff, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Diabetes. Although there has been interest in using oral oregano for diabetes, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Dysmenorrhea. Although there has been interest in using oral oregano for dysmenorrhea, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Dyspepsia. Although there has been interest in using oral oregano for dyspepsia, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Gingivitis. Although there has been interest in using topical oregano oil for gingivitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Headache. Although there has been interest in using topical oregano oil for headache, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Insect repellent. Although there has been interest in using topical oregano oil as an insect repellent, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Intestinal parasite infection. It is unclear if oral oregano is beneficial in patients with intestinal parasite infections. Details: In one small, uncontrolled study, taking a specific emulsified oregano leaf oil product (ADP, Biotics Research Corporation) 200 mg orally three times daily with meals for 6 weeks resulted in eradication of Blastocystis hominis, Entamoeba hartmanni, and Endolimax nana from the stool in 10 of 13 patients (6878). The clinical significance of this is unclear since the Centers for Disease Control (CDC) considers Entamoeba hartmanni and Endolimax nana to be non-pathogenic, while blastocystosis caused by Blastocystis hominis is usually self-limiting and does not require treatment.
• Pain (acute). Although there has been interest in using topical oregano oil for the relief of acute pain, including joint and muscle pain, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Psoriasis. Although there has been interest in using topical oregano oil for psoriasis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Rhinosinusitis. Although there has been interest in using oral oregano for rhinosinusitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Seborrheic dermatitis. Although there has been interest in using topical oregano oil for seborrheic dermatitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Tinea capitis. Although there has been interest in using topical oregano oil for tinea capitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Tinea corporis. Although there has been interest in using topical oregano oil for tinea corporis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Tinea pedis. Although there has been interest in using topical oregano oil for tinea pedis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Toothache. Although there has been interest in using topical oregano oil for toothache, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Upper respiratory tract infection (URTI). Although there has been interest in using oral oregano for URTIs, such as the common cold and influenza, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Urinary tract infections (UTIs). Although there has been interest in using oral oregano for UTIs, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Varicose veins. Although there has been interest in using topical oregano oil for varicose veins, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Warts. Although there has been interest in using topical oregano oil for warts, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Wound healing. It is unclear if topical oregano is beneficial for improving healing or preventing infections in people with skin wounds. Details: One small clinical trial shows that applying an ointment containing a 3% concentration of the water-soluble fraction of the oregano plant twice daily for 10-14 days after minor dermatological surgery might reduce infection rates and improve scar formation when compared with petrolatum ointment (67348). More evidence is needed to rate oregano for these uses.

(Read more about OREGANO)

LIKELY EFFECTIVE

• Irritable bowel syndrome (IBS). Oral enteric-coated peppermint oil is conditionally recommended by the American College of Gastroenterology (ACG) for the relief of global IBS symptoms, such as abdominal pain. Details: The ACG conditionally recommends the use of peppermint for the relief of global IBS symptoms. This recommendation is based on an available meta-analysis of generally low-quality clinical research (105124). Several clinical trials and meta-analyses show that taking enteric-coated peppermint oil 1-2 capsules orally two to four times daily reduces abdominal pain, distention, flatulence, and bowel movements in patients with IBS. Each capsule provides approximately 0.2 mL of peppermint oil or 180-225 mg peppermint oil. Most trials have used specific products (Colpermin, Tillotts Pharma; Mintoil, Cadigroup; Ibgard, IM HealthScience, Tempocol) (3802,3803,4469,11778,11779,17681,17682,68467,68515,68522)(68603,68604,68605,96360,99493,109980). The most recent meta-analysis to date shows that four patients would need to take peppermint oil to prevent one patient from having persistent IBS symptoms, and seven patients would need to take peppermint oil to prevent one patient from having abdominal pain. However, the individual studies included in the analysis lasted no more than 12 weeks (109980); any long-term effects are unclear. Although most studies have shown benefit for reducing symptoms, some older studies have found no significant effect (11777,11789) or only short-term benefits (68620). Also, a well-designed study shows that taking peppermint oil capsules designed for either small intestinal release (enteric-coated) or ileocolonic release does not increase the number of people with at least a 30% decrease in abdominal pain over a period of 4 weeks, although symptoms are modestly reduced when compared with placebo (102602). Another clinical trial in patients with moderate to severe IBS shows that taking a specific enteric-coated formulation of peppermint oil (Pepogest; Nature's Way) 180 mg three times daily for 6 weeks does not further improve symptom severity when compared with placebo. However, both groups experienced a large improvement on the IBS-Severity Scoring System (IBS-SSS) and the IBS Global Improvement Scale (107955). The validity of these findings is limited due to lost data and inconsistent follow-up; additionally, adverse effects occurred more frequently in the peppermint oil group. The reasons for these negative findings are unclear but may include short treatment durations and the use of different formulations; additionally, IBS is comprised of various subtypes and symptoms that can range in severity and presentation, which may alter treatment response. Some clinical research has also evaluated a specific combination product (Atrantil, KBS Research) containing peppermint leaf, red quebracho extract, and conker tree extract. Taking this product as needed for 2 weeks seems to reduce constipation and bloating when compared to baseline in patients with constipation-predominant IBS (95429,95430). It is unclear if the effects of this product are due to peppermint, the other ingredients, or the combination.

POSSIBLY EFFECTIVE

• Barium enema-related colonic spasm. Rectal peppermint, as part of barium enema preparations, seems to reduce colonic spasms during examination. Oral peppermint also seems to be beneficial. Details: Rectal use of peppermint oil, added as an ingredient in barium enema preparations, seems to relax the colon during barium enema examination and reduce the percentage of patients who experience colonic spasms by about 25% to 30% (6739,6749,12009). Adding peppermint oil to the barium enema seems to be at least as effective as using systemic scopolamine (Buscopan). Adding peppermint oil to the barium solution also does not seem to impair image quality (12009). Some clinical research also shows that taking peppermint oil orally before the start of a double-contrast barium enema examination decreases spasms and might also increase diagnostic quality (14467).
• Chemotherapy-induced nausea and vomiting (CINV). Oral and inhaled peppermint seem to reduce nausea and vomiting in patients with CINV. Details: Clinical research shows that adding peppermint oil, 40 drops in 20 mL water, every 8 hours following chemotherapy treatment to treatment with standard antiemetics reduces the severity of nausea, vomiting, and anorexia by moderate to large amounts over 48 hours when compared with a plain water placebo (105123). The use of peppermint oil aromatherapy has also been investigated. Clinical research shows that adding 2 drops of peppermint oil to a cool, damp washcloth for use on the neck as aromatherapy for about 30 minutes helps relieve chemotherapy-induced nausea by a small amount when compared with a washcloth without peppermint oil (102603). Additional clinical research in patients receiving standard antiemetics after chemotherapy shows that applying one drop of peppermint oil below the nose three times daily for 5 days reduces the severity of nausea and the frequency of nausea, vomiting, and retching by a moderate to large amount when compared with the antiemetics alone. These parameters were not improved following treatment with cisplatin (105122). In children with acute leukemia, a small clinical study shows that aromatherapy with 2 drops of peppermint oil and 3 drops of lemon oil in 80 mL of water diffused 30 minutes prior to and 2 and 4 hours after chemotherapy once weekly for 4 weeks decreases the severity of nausea, vomiting, and retching, and improves quality of life scores when compared with diffused water or no intervention (112015). The validity of these findings is limited by the use of patient-reported outcomes.
• Dyspepsia. Oral peppermint, in combination with caraway and possibly other ingredients, seems to reduce symptoms of dyspepsia. It is unclear if oral peppermint alone is beneficial. Details: Some clinical research shows that taking specific products containing peppermint and caraway oil (Enteroplant, Dr Willmar Schwabe Pharmaceuticals; Menthacarin, Dr Willmar Schwabe GmbH & Co.) improves quality of life and reduces symptoms of dyspepsia, including feelings of fullness, pain, and mild gastrointestinal spasms (6740,6741,10075,96344,102600). A meta-analysis of three of these clinical studies shows that taking this combination product 2-3 times daily for 4 weeks modestly reduces abdominal pain when compared with placebo (110091). Taking this combination twice daily for 4 weeks also improves postprandial distress syndrome and epigastric pain syndrome, two subtypes of dyspepsia, when compared with placebo (96344). The combination of enteric-coated peppermint oil 90 mg and caraway oil 50 mg appears to be comparable to cisapride for relieving dyspepsia when taken 2-3 times daily for up to 4 weeks (6740,6741,10075). However, most trials investigating this combination are small and/or of overall low quality (102600). A specific combination product containing peppermint leaf (Iberogast, Steigerwald Arzneimittelwerk GmbH) also seems to improve symptoms of dyspepsia. The combination includes peppermint leaf plus clown's mustard plant, German chamomile, caraway, licorice, milk thistle, angelica, celandine, and lemon balm (7049). A meta-analysis of studies using this combination product shows that taking 1 mL orally three times daily over a period of 4 weeks reduces the severity of acid reflux, epigastric pain, cramping, nausea, and vomiting when compared with placebo (13089). A similar combination product containing extracts from peppermint leaf, clown's mustard plant, German chamomile flower, caraway, licorice root, and lemon balm (STW 5-II, Steigerwald Arzneimittelwerk GmbH) 1 mL taken three times daily for up to 8 weeks eliminates gastrointestinal symptoms in 40% more dyspepsia patients when compared with placebo (12724).
• Endoscopy-associated adverse effects. Intraluminal peppermint seems to reduce spasticity during an endoscopy. It is unclear if oral peppermint is beneficial for reducing adverse effects related to endoscopy. Details: A meta-analysis of four clinical trials show that peppermint oil, administered orally or intraluminally, reduces the incidence of spasticity by about 41% when compared with placebo in patients undergoing endoscopy, with severe spasticity occurring at about 30% the rate of those taking placebo. However, there was no effect on subjective pain (102604). Individual clinical studies show that intraluminal peppermint oil can reduce both pain and spams in patients undergoing endoscopy (18220,68371,68395,68445,68532). However, there are limitations with this form of administration, including cost and practicality, which has led to interest in the use of oral formulations (104221). Studies evaluating oral extended-release peppermint have been conflicting. While one study shows that a specific extended-release peppermint oil product (Colpermin) 187 mg or 0.2 mL taken orally 4 hours prior to a colonoscopy reduces procedure time, pain, and spasticity (68532), a study using another specific extended-release peppermint oil (IBGard) did not show an effect on colonic spasms, procedure time, or adenoma detection rate when compared with placebo (104221). These differing outcomes may be due to timing of administration. The study that showed benefit administered the treatment 4 hours prior to endoscopy, whereas the study showing no benefit administered the treatment only 1 hour prior. This suggests that extended-release peppermint may need to be administered at least 4 hours prior to the procedure to allow for adequate colonic release (68532,102604,104221).
• Nipple fissures. Topical peppermint seems to reduce cracked skin and pain in the nipples due to breastfeeding. Details: Clinical research shows that topical application of peppermint oil in gel or water reduces cracked skin and pain in the nipple area from breastfeeding when compared with using placebo, lanolin, or the expressed breast milk technique (68454,68462). Other research shows that applying peppermint oil in cream immediately after breastfeeding for 2 weeks decreases pain and trauma in the nipple area similarly to the topical application of dexpanthenol or lanolin (96365).
• Pressure ulcers. Topical peppermint seems to reduce the risk of pressure ulcers. Details: Clinical research in bedridden patients shows that prophylactic application of a topical gel containing peppermint oil 0.2% three times daily for up to 14 days results in pressure injuries in about 23% of patients compared with 77% of those given a placebo gel (102605).
• Tension headache. Topical peppermint seems to relieve tension headaches. Details: Clinical research shows that topical application of peppermint oil 10% relieves tension headaches when compared with placebo (3801,6190).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Abdominal pain. Although there has been interest in using oral peppermint for abdominal pain, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Anxiety. It is unclear if inhaled peppermint oil is beneficial for reducing anxiety. Details: A clinical trial in patients presenting to the emergency department for an acute coronary syndrome event shows that placing 3 drops of peppermint oil on a cotton ball and inhaling for 1 hour improves anxiety and respiratory rate when compared with baseline or placebo (107958). Due to the single-dose nature of this study, the effects of repeated inhalation of peppermint oil are unclear.
• Breast cancer-related hot flashes. It is unclear if topical peppermint is beneficial for reducing hot flashes in patients with breast cancer. Details: Preliminary clinical research shows that using a spray containing a combination of peppermint and neroli hydrolat does not alleviate hot flashes in most patients receiving chemotherapy for breast cancer when compared with using a plain water spray (68481).
• Cognitive function. It is unclear if inhaled peppermint oil is beneficial for improving cognitive function. Details: Preliminary clinical research shows that inhalation of peppermint oil slightly improves memory and the performance of cognitive tasks such as typing, alphabetization, and ordering, but not attention and speed of task completion, when compared with control (56954,68416,68466).
• Common cold. Although there has been interest in using oral, topical, or inhaled peppermint for the common cold, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Dental plaque. Topical peppermint has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that rinsing the mouth for one minute with 10 mL of a specific combination product (HiOra, Himalaya Herbal Healthcare) containing peppermint oil and numerous other ingredients twice daily for two days reduces plaque index or plaque area when compared with placebo; however, it was not as effective as chlorhexidine 0.2% solution (68530). It is unclear if these effects are due to peppermint oil, other ingredients, or the combination.
• Diffuse esophageal spasm. It is unclear if oral peppermint oil is beneficial for diffuse esophageal spasm. Details: A small exploratory study in adults with diffuse esophageal spasm shows that drinking a solution of peppermint oil, 5 drops in 10 mL of water, can resolve esophageal contractions when compared with baseline (13415). The validity of this finding is limited by the lack of a comparator group.
• Dysmenorrhea. It is unclear if oral peppermint oil is beneficial for reducing menstrual pain. Details: Preliminary clinical research shows that taking three capsules of peppermint oil (Colpermin; Tillotts Company or Razak company) daily for 3 days, starting on the first day of menstruation, is as effective as mefenamic acid 250 mg three times daily for reducing pain, and more effective for reducing nausea and vomiting, associated with dysmenorrhea. However, mefenamic acid was more effective for reducing bleeding and analgesic use (105125).
• Fatigue. It is unclear if inhaled peppermint oil improves fatigue in patients with cardiac disease. Details: A clinical trial in hospitalized patients with various forms of cardiac disease shows that placing 3 drops of peppermint oil on a cotton ball and inhaling for 20 minutes nightly for 7 days improves fatigue scores when compared with placebo. These improvements were similar to those seen with lavender oil inhalation. Fatigue scores decreased by 24 and 21 points in the peppermint and lavender groups, respectively, compared with a 2-point reduction in the placebo group (107959). The validity of these findings is limited due to the short duration of treatment.
• Halitosis. Peppermint has only been evaluated in combination with other ingredients as a mouthwash; its effect when used alone is unclear. Details: Preliminary clinical research shows that rinsing the mouth with a specific combination of tea tree oil, peppermint, and lemon essential oil once for three minutes improves breath smell when compared with placebo or benzydamine hydrochloride (19177).
• Insomnia. It is unclear if inhaled peppermint oil is beneficial for insomnia. Details: Preliminary clinical research in cancer patients shows that receiving aromatherapy as three drops of peppermint oil applied to a cotton ball and attached to the collar for 20 minutes at bedtime for one week improves sleep when compared with baseline. However, it seems to be no better than using lavender oil aromatherapy or using a control of lavender oil 1% (103063).
• Menopausal symptoms. Although there has been interest in using inhaled peppermint oil for menopausal symptoms, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Migraine headache. It is unclear if intranasal peppermint oil is beneficial for migraine headache. Details: Preliminary clinical research shows that using 1-2 doses of intranasal peppermint oil 1.5% (Poursina Company) at the start of migraine pain is as effective as intranasal lidocaine 4%, and more effective than placebo, for reducing migraine headache intensity. Approximately 42% of those using peppermint oil indicated a high level of headache reduction, compared with 42% of those using lidocaine and 5% of those using placebo. Also, pain relief was felt within 5 minutes in more patients using peppermint than placebo (105126). However, it is unclear if participants were truly blinded to the use of peppermint oil.
• Mosquito repellent. Although there has been interest in using topical peppermint oil as a mosquito repellent, there is insufficient reliable information about the clinical effects of peppermint for this purpose.
• Myalgia. Although there has been interest in using topical peppermint oil for myalgia, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Oral mucositis. Topical peppermint has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in adults undergoing stem cell transplantation shows that using an oral rinse containing peppermint oil and German chamomile three times daily, in addition to standard treatment with sodium chloride and chlorhexidine, reduces the duration and severity of mucositis and the use of narcotic analgesics when compared with placebo and standard treatment. However, this oral rinse does not reduce or delay the occurrence of mucositis or affect the duration of hospitalization (96363). Another small clinical study in adults with head and neck cancers undergoing radiation shows that rinsing with 5 mL of a polyherbal mouthwash containing peppermint oil, German chamomile, aloe vera, and honey for 1 minute 3 times daily for 6 weeks reduces oral mucositis incidence, severity, and pain when compared with chlorhexidine 0.2% and placebo (111291). Clinical research in adults receiving treatment with 5-fluorouracil shows that using an oral rinse containing peppermint, sage tea, and thyme in addition to basic oral care, starting on the first day of chemotherapy and continuing for 14 days, delays the onset of mucositis, but not the rate or severity of mucositis, when compared with basic oral care alone (96364). It is unclear if these effects are due to peppermint oil, other ingredients, or the combinations.
• Osteoarthritis. Although there has been interest in using topical peppermint oil for osteoarthritis, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Pain (acute). It is unclear if inhaled peppermint oil is beneficial for acute pain. Details: Preliminary clinical research in cardiac patients shows that peppermint oil aromatherapy reduces pain associated with intravenous catheterization by a small amount when compared with a distilled water control (102601).
• Postherpetic neuralgia. Although there has been interest in using topical peppermint oil for postherpetic neuralgia, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Postoperative ileus. It is unclear if oral peppermint oil is beneficial for the prevention of postoperative ileus. Details: Clinical research shows that taking a specific peppermint oil product (Colpermin, Tillotts Pharma) as two capsules three times daily for 5 days after routine gynecological surgery does not prevent postoperative abdominal distension and dyspepsia when compared with placebo (68602). Conversely, a small clinical study in patients undergoing elective cesarean section shows that taking 20 drops of peppermint oil 4 hours after surgery and then hourly for a total of three doses reduces the time to first bowel sounds by around 3.3 hours, first flatulence by 4.4 hours, and first stool by 5 hours when compared with placebo (110092).
• Postoperative nausea and vomiting (PONV). Some preliminary clinical studies suggest that inhaled peppermint may be beneficial for PONV. However, it is unclear if the benefit is due to aromatherapy or improved breathing patterns. Details: Some preliminary clinical research shows that using peppermint aromatherapy helps relieve postoperative nausea (3804,13415,68524,104219,104220). Inhaling peppermint oil 10% and 30% as aromatherapy reduces the severity of nausea when compared with placebo, with no significant difference between concentrations (104220). Small clinical trials show improvement in PONV within the first 4 hours after surgery. However, this effect diminishes beyond 4 hours (104219). Other preliminary clinical research shows that peppermint oil aromatherapy is no more effective for reducing postoperative nausea than inhaling isopropyl alcohol or saline (13416,68529). It is possible that any relief of postoperative nausea observed with peppermint aromatherapy results from improved breathing patterns after surgery rather than peppermint oil itself (13416,90512). One small study shows that inhaling peppermint oil while practicing controlled breathing does not appear to relieve PONV better than practicing controlled breathing alone (90512). Some preliminary clinical research shows that inhaling vapors from a mixture of peppermint, ginger, spearmint, and cardamom essential oils reduces symptoms of postoperative nausea in approximately 15% more patients when compared with inhaling ginger essential oils alone, and in approximately 43% more patients when compared with inhaling saline (89888). However, it is not clear if the effect is due to peppermint, the other oils, or the combination.
• Pre-procedural anxiety. It is unclear if inhaled peppermint oil is beneficial for reducing anxiety prior to a medical procedure. Details: Preliminary clinical research in cardiac patients shows that peppermint oil aromatherapy does not reduce anxiety associated with intravenous catheterization when compared with a distilled water control (102601).
• Pregnancy-induced nausea and vomiting. Inhaled peppermint oil has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that aromatherapy with a mixture of 5% lemon and 5% peppermint essential oils modestly reduces the intensity of nausea and vomiting on days 2-4, but not day 1, when compared with placebo aromatherapy. When nauseated, patients placed three drops of the essential oil mixture (Barij Essence Co.) onto a cotton ball held 3 cm from the nose. This action could be repeated after 5 minutes if needed (105121).
• Pruritus. Some preliminary clinical studies suggest that topical peppermint oil improves itching of various etiologies. Details: Preliminary clinical research in adults with renal, hepatic, or diabetic pruritus shows that topical application of peppermint oil 5% in petrolatum twice daily for 2 weeks improves symptoms of pruritus when compared with petrolatum alone (96361). Preliminary clinical research in patients with severe or intractable pruritus secondary to burn scars shows that applying a specific product (Chongqing No.1, CQ-01, MJ Medical Gel Systems Ltd.) containing peppermint oil 3.6%, menthol 1.4%, and methyl salicylate 2.5%, covered with gauze for 24 hours, reduces the severity of pruritus for up to 7 days after application when compared with hydrogel covered with gauze or with gauze alone (96362). Preliminary clinical research in females experiencing itchy skin due to intrahepatic cholestasis of pregnancy also shows that applying peppermint oil 0.5% in sesame oil twice daily for 2 weeks reduces pruritus severity approximately 1.8-fold when compared with sesame oil alone (89478).
• Small intestinal bacterial overgrowth (SIBO). Although there has been interest in using oral peppermint for SIBO, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Stress. It is unclear if inhaled peppermint oil is beneficial for stress. Details: Clinical research shows that peppermint aromatherapy decreases physical and perceived levels of stress when compared with baseline (68422,68517). A small clinical study in adults undergoing a virtual reality (VR) driving scenario to test road rage shows that exposure to peppermint oil (Pure Essential Oil of Peppermint, Tisserand Aromatherapy) 5 drops via fan diffuser improves aggressive driving behavior scores but does not seem to improve self-reported stress, aggression, alertness, happiness, or calmness when compared with controls that did not receive aromatherapy during the VR session (112017).
• Toothache. Although there has been interest in using topical peppermint oil for toothache, there is insufficient reliable information about the clinical effects of peppermint for this condition.
• Urticaria. Although there has been interest in using topical peppermint oil for urticaria, there is insufficient reliable information about the clinical effects of peppermint for this condition. More evidence is needed to rate peppermint for these uses.

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

POSSIBLY SAFE ...when caraway oil is used orally in medicinal amounts. Caraway oil has been used with apparent safety at a dose of up to 150 mg daily for up to 4 weeks, in combination with peppermint oil (6740,6741,6742,10075,96344). ...when caraway seed is used orally, short-term. An aqueous caraway seed extract has been used with apparent safety at a dose of 3 grams daily for up to 3 months (94086,94087,94088). ...when used topically and appropriately. A heated poultice containing caraway oil 2% has been used with apparent safety for up to 3 weeks (94085).

PREGNANCY: POSSIBLY UNSAFE
when used in medicinal amounts (4912,6746). Caraway oil has been used to stimulate menstruation (6746); avoid using.

LACTATION:
Insufficient reliable information available; avoid using.

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LIKELY SAFE ...when used orally in amounts commonly found in foods. Oregano leaf and oil have Generally Recognized as Safe (GRAS) status in the US (4912). There is insufficient reliable information available about the safety of oregano when used orally in amounts greater than those found in food. There is also insufficient reliable information available about the safety of oregano when used topically. Oregano oil in concentrations of greater than 1% may be irritating when applied to mucous membranes (67348,88188).

PREGNANCY: POSSIBLY UNSAFE
when used orally in medicinal amounts. Oregano is thought to have abortifacient and emmenagogue effects (19,7122,19104).

LACTATION:
There is insufficient reliable information available about the safety of oregano when used in medicinal amounts; avoid amounts greater than those found in food.

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LIKELY SAFE ...when peppermint oil is used orally, topically, or rectally in medicinal doses. Peppermint oil has been safely used in multiple clinical trials (3801,3804,6190,6740,6741,10075,12009,13413,14467,17681)(17682,68522,96344,96360,96361,96362,96363,96364,96365,99493).

POSSIBLY SAFE ...when peppermint leaf is used orally and appropriately, short-term. There is some clinical research showing that peppermint leaf can be used safely for up to 8 weeks (12724,13413). The long-term safety of peppermint leaf in medicinal doses is unknown. ...when peppermint oil is used by inhalation as aromatherapy (7107). There is insufficient reliable information available about the safety of using intranasal peppermint oil.

CHILDREN: POSSIBLY SAFE
when used orally for medicinal purposes. Enteric-coated peppermint oil capsules have been used with apparent safety under medical supervision in children 8 years of age and older (4469).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods (96361). There is insufficient information available about the safety of using peppermint in medicinal amounts during pregnancy or lactation; avoid using.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might increase the risk of hypoglycemia when used with antidiabetes drugs.  Details Animal research suggests that caraway can reduce blood glucose levels (12736,39844). Monitor blood glucose levels closely. Medication dose adjustments may be necessary.

CNS DEPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might increase the effects and adverse effects of CNS depressants.  Details Animal research suggests that (S)-(+)-carvone, a major constituent of caraway seed extract, has sedative effects (39800).

CYTOCHROME P450 1A1 (CYP1A1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might increase the levels and clinical effects of CYP1A1 substrates.  Details In vitro evidence suggests that caraway extract can inhibit the activity of CYP1A1 in a dose-dependent manner (39780). This interaction has not been reported in humans.

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might increase the risk of hypokalemia when used with diuretics that deplete potassium.  Details Animal research suggests that a single dose of caraway fruit extract can promote diuresis and increase the urinary excretion of sodium and potassium. However, sub-chronic use of caraway fruit extract does not seem to significantly increase potassium excretion, although urine output continues to be increased for up to 6 days (39797).

ISONIAZID Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might increase the effects and adverse effects of isoniazid.  Details Animal research suggests that a specific fraction of caraway seed extract (CC-1a) can increase plasma levels of isoniazid when administered concomitantly (25529). This interaction has not been reported in humans.

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might reduce excretion and increase levels of lithium due to diuretic effects.  Details Animal research suggests that caraway fruit extract has diuretic properties (39797).

PYRAZINAMIDE Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might increase the effects and adverse effects of pyrazinamide.  Details Animal research suggests that a specific fraction of caraway seed extract (CC-1a) can increase plasma levels of pyrazinamide when administered concomitantly (25529). This interaction has not been reported in humans.

RIFAMPIN (Rifadin) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, caraway might increase the effects and adverse effects of rifampin.  Details Animal research suggests that a specific fraction of caraway seed extract (CC-1a) can increase plasma levels of rifampin when administered concomitantly (25529). This interaction has not been reported in humans.

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ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, oregano might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.  Details In vitro research shows that aristolochic acid isolated from oregano leaves has antithrombin activity (67164). It has also been reported that oregano oil inhibits arachidonic acid-induced, and ADP-induced, platelet aggregation (49445).

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, oregano might increase the risk for hypoglycemia when taken with antidiabetes drugs.  Details In vitro and animal research shows that oregano extracts might lower blood glucose levels (67191,67204,110122).

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CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, peppermint oil might increase the levels and adverse effects of cyclosporine.  Details In animal research, peppermint oil inhibits cyclosporine metabolism and increases cyclosporine levels. Inhibition of cytochrome P450 3A4 (CYP3A4) may be partially responsible for this interaction (11784). An interaction between peppermint oil and cyclosporine has not been reported in humans.

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, peppermint might increase the levels of CYP1A2 substrates.  Details In vitro and animal research shows that peppermint oil and peppermint leaf inhibit CYP1A2 (12479,12734). However, in clinical research, peppermint tea did not significantly affect the metabolism of caffeine, a CYP1A2 substrate. It is possible that the 6-day duration of treatment may have been too short to identify a difference (96359).

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, peppermint might increase the levels of CYP2C19 substrates.  Details In vitro research shows that peppermint oil inhibits CYP2C19 (12479). So far, this interaction has not 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, peppermint might increase the levels of CYP2C9 substrates.  Details In vitro research shows that peppermint oil inhibits CYP2C9 (12479). So far, this interaction 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 = B Theoretically, peppermint might increase the levels of CYP3A4 substrates.  Details Clinical research in healthy volunteers shows that a single dose of peppermint oil 600 mg inhibits CYP3A4 enzymes and increases the AUC of felodipine, a CYP3A4 substrate (11783). However, in vitro research suggests that peppermint oil only inhibits CYP3A4 at very high concentrations (12479).

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General ...Orally, caraway oil seems to be well tolerated.

Gastrointestinal ...Orally, caraway oil, when used in combination with peppermint oil, may cause a substernal burning sensation, belching, nausea, and vomiting (6741,6742,10075,96344). It is unclear if these adverse effects are due to caraway oil, peppermint oil, or the combination. Peppermint oil, when used alone, has been reported to cause similar adverse effects.

Immunologic ...Orally, an allergic reaction has been reported after use of caraway oil in combination with peppermint oil in a patient with a history of bronchial asthma (96344). It is unclear if this adverse effect is due to caraway oil, peppermint oil, or the combination.

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General ...Orally, oregano is well tolerated when used in amounts typically found in foods. There is currently a limited amount of information available about the safety of oregano when used in larger amounts as medicine.
Most Common Adverse Effects:
Orally: Gastrointestinal upset.
Topically: Dermatitis in sensitive individuals.
Serious Adverse Effects (Rare):
Orally: Systemic allergic reactions, including anaphylaxis, in sensitive individuals.

Dermatologic ...Oregano has been reported to cause allergic contact dermatitis (46902). Topically, oregano oil in concentrations of greater than 1% has been reported to cause irritation when applied to mucous membranes (67348,88188).

Gastrointestinal ...Orally, large amounts of oregano can cause gastrointestinal upset. Concentrated, non-emulsified oil of oregano can cause localized irritation of the gastrointestinal tract (6878).

Immunologic ...Systemic allergic reactions have been reported with oregano. A 45-year-old male developed pruritus, respiratory difficulty, hypotension, swelling of the lips and tongue, and facial edema after ingesting pizza seasoned with oregano. He had 2 similar episodes after ingesting foods seasoned with thyme, another member of the Lamiaceae family. He did not react to similar foods without the seasoning, and he had positive skin tests to plants of the Lamiaceae family (3705).

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General ...Orally, topically, or rectally, peppermint oil is generally well tolerated. Inhaled, peppermint oil seems to be well tolerated. Intranasally, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted. Orally, peppermint leaf seems to be well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, anal burning, belching, diarrhea, dry mouth, heartburn, nausea, and vomiting.
Topically: Burning, dermatitis, irritation, and redness.

Dermatologic ...Topically, peppermint oil can cause skin irritation, burning, erythema, and contact dermatitis (3802,11781,31528,43338,68473,68457,68509,96361,96362). Also, a case of severe mucosal injury has been reported for a patient who misused an undiluted over the counter mouthwash that contained peppermint and arnica oil in 70% alcohol (19106).
In large amounts, peppermint oil may cause chemical burns when used topically or orally. A case of multiple burns in the oral cavity and pharynx, along with edema of the lips, tongue, uvula, and soft palate, has been reported for a 49-year-old female who ingested 40 drops of pure peppermint oil. Following treatment with intravenous steroids and antibiotics, the patient's symptoms resolved over the course of 2 weeks (68432). Also, a case of chemical burns on the skin and skin necrosis has been reported for a 35-year-old male who spilled undiluted peppermint oil on a previous skin graft (68572). Oral peppermint oil has also been associated with burning mouth syndrome and chronic mouth ulceration in people with contact sensitivity to peppermint (6743). Also, excessive consumption of mint candies containing peppermint oil has been linked to cases of stomatitis (13114).

Gastrointestinal ...Orally, peppermint oil can cause heartburn, nausea and vomiting, anal or perianal burning, abdominal pain, belching, dry mouth, diarrhea, and increased appetite (3803,6740,6741,6742,10075,11779,11789,17682,68497,68514)(68532,68544,96344,96360,102602,104219,107955). Enteric-coated capsules might help to reduce the incidence of heartburn (3802,4469,6740,11777). However, in one clinical study, a specific enteric-coated formulation of peppermint oil (Pepogest; Nature's Way) taken as 180 mg three times daily was associated with a higher rate of adverse effects when compared with placebo (48% versus 31%, respectively). Specifically, of the patients consuming this product, 11% experienced belching and 26% experienced heartburn, compared to 2% and 12%, respectively, in the placebo group (107955). A meta-analysis of eight small clinical studies in patients with irritable bowel syndrome shows that taking enteric-coated formulations of peppermint oil increases the risk of gastroesophageal reflux symptoms by 67% when compared with a control group (109980). Enteric-coated capsules can also cause anal burning in people with reduced bowel transit time (11782,11789).

Genitourinary ...Orally, a sensitive urethra has been reported rarely (102602).

Hepatic ...One case of hepatocellular liver injury has been reported following the oral use of peppermint. Symptoms included elevated liver enzymes, fatigue, jaundice, dark urine, and signs of hypersensitivity. Details on the dosage and type of peppermint consumed were unavailable (96358).

Immunologic ...One case of IgE-mediated anaphylaxis, characterized by sudden onset of lip and tongue swelling, tightness of throat, and shortness of breath, has been reported in a 69-year-old male who consumed peppermint candy (89479). An allergic reaction after use of peppermint oil in combination with caraway oil has been reported in a patient with a history of bronchial asthma (96344). It is not clear if this reaction occurred in response to the peppermint or caraway components.

Neurologic/CNS ...Orally, headache has been reported rarely (102602).

Ocular/Otic ...Orally, peppermint has been reported to cause blurry vision (3803).

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