Sexual Health by GNC Men's

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Obesity. Oral cola nut has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in overweight and obese adults shows that taking cola nut 1500 mg daily for 3 months, in combination with ephedra and willow bark, modestly increases weight loss (12811). Other preliminary clinical research shows that taking an herbal treatment containing ephedra and cola nut for 6 months reduces body weight by 2.7 kg and body fat by 1.6 kg when compared with placebo in overweight and obese individuals (8647). Ephedra is banned in the US due to the risk for severe adverse effects (10055). More evidence is needed to rate cola nut for this use.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Asthma. Although there has been interest in using oral damiana for asthma, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Cognitive function. Although there has been interest in using oral damiana for cognitive function, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Constipation. Although there has been interest in using oral damiana for constipation, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Depression. Although there has been interest in using oral damiana for depression, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Diabetes. Although there has been interest in using oral damiana for diabetes, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Dyspepsia. Although there has been interest in using oral damiana for dyspepsia, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Erectile dysfunction (ED). Oral damiana has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized, open-label clinical study in adults with mild-to-moderate ED shows that taking a specific combination supplement (Icarifil, Anvest Health S.p.A) containing damiana 100 mg, panax ginseng, L-carnitine, L-citrulline, tribulus, and other ingredients daily for 3 months improves patient-reported erectile function when compared to baseline. Additionally, taking the supplement with tadalafil improves some, but not all, patient-reported assessments of erectile function when compared with taking tadalafil alone (114989). It is unclear if this effect is due to damiana, other ingredients, or the combination. Additionally, the interpretation of these results is limited by poor methodology, including the use of per-protocol analysis and lack of a placebo group.
• Headache. Although there has been interest in using oral damiana for headache, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Menopausal symptoms. Although there has been interest in using oral damiana for menopausal symptoms, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Obesity. Oral damiana has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in overweight adults shows that taking a combination product containing damiana 36 mg, guarana 95 mg, and yerba mate 112 mg, orally three times daily for 45 days increases weight loss when compared with placebo (11866). It is unclear if this effect is due to damiana, other ingredients, or the combination.
• Nocturnal enuresis. Although there has been interest in using oral damiana for nocturnal enuresis, there is insufficient reliable information about the clinical effects of damiana for this purpose.
• Sexual dysfunction. Oral damiana has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a specific combination product containing damiana, L-arginine, Panax ginseng, ginkgo, vitamins, and minerals (ArginMax for Women, Daily Wellness Co.) improves sexual satisfaction and desire, increases orgasm frequency, and reduces vaginal dryness when compared with placebo in females interested in improving their sexual function (46933). It is unclear if this effect is due to damiana, other ingredients, or the combination. More evidence is needed to rate damiana for these uses.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Anxiety. Although there has been interest in using oral GABA for anxiety, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Athletic performance. Although there has been interest in using sublingual GABA for athletic performance, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Attention deficit-hyperactivity disorder (ADHD). Although there has been interest in using oral GABA for ADHD, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Cerebral palsy. It is unclear if oral GABA is beneficial for cerebral palsy in children. Details: Preliminary clinical research in children with cerebral palsy shows that taking a specific product containing GABA (Gammalon) one to four tablets daily (depending on age) for 2 months, in addition to standard therapy for cerebral palsy, improves mental development, learning, vocabulary, physical function, motor strength and activity, and motor hyperactivity in a greater percentage of children when compared with standard therapy alone (19362). These findings are limited by poor study design.
• Chronic bronchitis. It is unclear if oral GABA is beneficial for chronic bronchitis. Details: Preliminary clinical research in adults with chronic bronchitis shows that taking a specific GABA product (Aminalon) 1.5-3 grams daily for 18-20 days, along with conventional treatment for acute exacerbations of bronchitis, increases the duration of subsequent remission by about 3 months when compared with conventional treatment alone (19361).
• Cushing syndrome. It is unclear if oral GABA is beneficial for Cushing syndrome. Details: Preliminary clinical research shows that taking a specific GABA product (Aminalon) 1-3 grams daily for one month decreases plasma levels of adrenocorticotropic hormone (ACTH) 60 minutes after administration, as well as cortisol and ACTH levels up to 2 days after GABA discontinuation, when compared with baseline (19363). The validity of these findings is limited by the lack of a comparator group.
• Depression. Although there has been interest in using oral GABA for depression, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Epilepsy. It is unclear if oral GABA is beneficial for epilepsy. Details: Preliminary clinical research shows that taking a combination of GABA 2.5-3 grams and phosphatidylserine 500 mg daily for 3-8 months reduces seizure frequency when compared with placebo in patients with absence seizures, but not in those with focal aware or focal impaired awareness seizures (19364). Other preliminary clinical research suggests that taking GABA 3 grams with phosphatidylserine 600-1200 mg daily for 2 days does not affect the seizure photosensitivity range in people with photoconvulsive responses (5113).
• Hypertension. Preliminary clinical research suggests that oral GABA may modestly reduce blood pressure in patients with mild or borderline hypertension. Details: Preliminary clinical research in adults with hypertension shows that drinking 100 mL of fermented milk containing GABA 10-12 mg daily at breakfast for 12 weeks reduces systolic and diastolic blood pressure by about 17 mmHg and 7 mmHg, respectively, when compared with baseline. Compared with patients treated with a placebo milk, these reductions were significant. However, it is unclear if the placebo milk also differed from the fermented milk in other ways (19367). Other preliminary clinical research in patients with borderline hypertension shows that taking a chlorella supplement containing GABA 20 mg twice daily for 12 weeks reduces systolic blood pressure when compared with placebo (19368). However, these findings are limited by poor study design.
• Insomnia. It is unclear if oral GABA is beneficial for insomnia. Details: Two small clinical studies in adults with insomnia show that taking fermented rice germ extract, standardized to provide GABA 75 mg or 300 mg, one hour before bedtime for 4 weeks modestly decreases sleep latency when compared with placebo, but does not improve sleep efficacy or reduce episodes of waking after sleep onset (110134,110135). As these doses were evaluated in separate studies, no direct comparison between GABA 75 mg and 300 mg has been conducted.
• Meningitis. It is unclear if oral GABA is beneficial for meningitis. Details: Preliminary clinical research in children aged 7 months to 16 years with meningitis shows that taking a specific GABA product (Aminalon) 0.5-1.5 grams daily, starting within 2-4 weeks of illness and continuing for one month thereafter, decreases the incidence of residual disease manifestations and prevents the development of cerebrospinal syndrome when compared with control (19369). However, this study was conducted prior to the development of current treatment guidelines for meningitis; it is unclear if GABA is beneficial when used in conjunction with current standard care.
• Menopausal symptoms. Although there has been interest in using oral GABA for menopausal symptoms, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Motion sickness. It is unclear if oral GABA is beneficial for motion sickness. Details: Preliminary clinical research shows that taking a specific GABA product (Aminalon) 0.5 grams as a single dose 40-50 minutes before induced motion sickness or three times daily for 4 days significantly delays onset of motion sickness when compared with placebo. GABA also decreases the occurrence of motion sickness symptoms including chills, cold sweats, and pallor when compared with placebo (19370).
• Obesity. Although there has been interest in using oral and sublingual GABA for weight loss, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Pain (acute). Although there has been interest in using oral and sublingual GABA for acute pain, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Post-traumatic stress disorder (PTSD). Although there has been interest in using oral GABA for PTSD, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Prediabetes. It is unclear if oral GABA is beneficial for prediabetes. Details: A small clinical study in adults with prediabetes and overweight or obesity shows that taking GABA 500 mg (GABA, Swanson Health) 3 times daily for 95 days does not improve postprandial glucose response to oral glucose tolerance testing, fasting glucose, glycated hemoglobin (HbA1c), or glycemic variability when compared with placebo (112830).
• Premenstrual syndrome (PMS). Although there has been interest in using oral GABA for PMS, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Psychological well-being. Although there has been interest in using oral and sublingual GABA to improve well-being, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Stress. It is unclear if oral GABA is beneficial for stress. Details: Preliminary clinical research shows that taking a single dose of GABA 100-200 mg by mouth 10-70 minutes prior to completing a mentally stressful task does not appear to reduce subjective measure of stress when compared with placebo (90568). However, it does attenuate alpha wave reduction and reduces beta wave upsurge on the EEG during testing when compared with placebo (19373,90568). More evidence is needed to rate GABA for these uses.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Bronchitis. Although there is interest in using oral horny goat weed for bronchitis, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Coronary heart disease (CHD). Although there is interest in using oral horny goat weed for CHD, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Erectile dysfunction (ED). Although there is interest in using oral horny goat weed for ED, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Fatigue. Although there is interest in using oral horny goat weed for fatigue, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Gulf war syndrome. It is unclear if oral horny goat weed is beneficial in patients with Gulf war syndrome. Details: A small clinical study in males with Gulf war syndrome shows that taking horny goat weed extract 250 mg or 500 mg twice daily, standardized to contain 50 mg or 100 mg of icariin per dose, respectively, for 30 days does not improve symptoms of Gulf war syndrome when compared with placebo (108311).
• Hepatitis. Although there is interest in using oral horny goat weed for hepatitis, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• HIV/AIDS. Although there is interest in using oral horny goat weed for HIV/AIDS, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Hypertension. Although there is interest in using oral horny goat weed for hypertension, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Male infertility. Although there is interest in using oral horny goat weed for male infertility, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Memory. Although there is interest in using oral horny goat weed for memory, there is insufficient reliable information about the clinical effects of horny goat weed for this purpose.
• Myocarditis. Although there is interest in using oral horny goat weed for myocarditis, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Osteoarthritis. Although there is interest in using oral horny goat weed for osteoarthritis, there is insufficient reliable information about the clinical effects of horny goat weed for this condition.
• Osteoporosis. Several small, low-quality clinical studies suggest that horny goat weed may modestly improve bone mineral density (BMD) in patients with osteoporosis. Details: A meta-analysis of 12 small, low-quality clinical studies in patients with osteoporosis shows that taking horny goat weed alone or in combination with conventional therapy improves BMD when compared with a control group. When added to conventional therapy, horny goat weed appears to have a large effect on BMD, while its effect is more modest when used alone. The most common formulations and doses used include granules 1 gram twice daily for 6 months, an extract 600 mg taken in divided doses daily for 6 months, and a decoction 50 mL taken 2-3 times daily for 3-6 months. The pooled analysis suggests that horny goat weed decoctions are more effective than other formulations (109578). Additionally, a small clinical study in postmenopausal patients not included in the analysis above shows that taking a specific extract of horny goat weed containing 60 mg icariin, 15 mg daidzein, and 3 mg genistein (Xianling Gubao; Tong Ji Tang Pharmacal Company) daily, in addition to calcium 300 mg daily, for 24 months attenuates loss of BMD of the lumbar spine and femoral neck when compared with placebo plus calcium. BMD increased by 1.6% and 1.3% at each site, respectively, compared with decreases of 1.8% and 2.4%, respectively, with placebo (14900).
• Postmenopausal conditions. It is unclear if oral horny goat weed is beneficial in patients with postmenopausal conditions. Details: Preliminary clinical research in postmenopausal patients shows that taking horny goat weed water extract 300 mL daily for 6 months slightly decreases triglyceride and total cholesterol levels and can increase estradiol levels when compared with placebo (55452). The clinical significance of these effects is unclear.
• Sexual dysfunction. Although there is interest in using oral horny goat weed for sexual dysfunction, there is insufficient reliable information about the clinical effects of horny goat weed for this condition. More evidence is needed to rate horny goat weed for these uses.

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POSSIBLY EFFECTIVE

• Angina. Oral L-arginine seems to improve symptoms and exercise tolerance in patients with angina. Details: Clinical research shows that taking L-arginine orally seems to decrease symptoms and improve exercise tolerance and quality of life in patients with mild to severe angina (3593,7815,7816,31866,31923). Some patients with severe angina who have frequent attacks at rest despite treatment with standard antianginal agents might also benefit from L-arginine (3593). However, L-arginine does not seem to improve objective measures of blood vessel dilation or increase circulating concentrations of nitric oxide (7817,99262). Also, when used in combination with ten 200 mcg injections of vascular endothelial growth factor (VEGF)-165 plasmid DNA, L-arginine 6 grams daily orally for 3 months does not improve angina severity in patients with coronary artery disease who underwent surgical angiogenesis compared to patients who did not receive this combination (32001). In addition, intravenous infusion of arginine 10% solution does not improve exercise capacity in patients with stable angina when compared with placebo (31843,32293).
• Erectile dysfunction (ED). Oral L-arginine might improve symptoms of ED. When taken with phosphodiesterase type 5 (PDE5) inhibitors, L-arginine seems to provide a small additional benefit. Details: Taking L-arginine orally in high doses, 5 grams daily, improves subjective assessment of sexual function in males with organic ED when compared with placebo (222,102586). Additionally, a meta-analysis of 4 small clinical studies in patients with ED, including those with diabetes and/or cardiovascular disease risk factors, shows that although PDE5 inhibitors improve sexual function better than L-arginine, the combination of PDE5 inhibitors and L-arginine may be more effective than either treatment alone (105065). In most clinical trials, doses of L-arginine 2.5-5 mg daily for 6-12 weeks were used alone or in addition to PDE5 inhibitors such as sildenafil 50 mg or tadalafil 5-10 mg daily (102586,102587,102592,104222). Higher doses have also been investigated. One clinical trial shows that taking L-arginine (Bioarginina, Farmaceutici Damor S.p.A., Napoli, Italy), 2 grams three times daily for 3 months improves sexual function compared with placebo (110387). However, taking lower doses, 1.5 grams daily, might not be effective in patients with mixed-type ED (2038). L-arginine has also been examined in combination with other ingredients. A meta-analysis of 2 small clinical studies in males with mild-to-moderate ED shows that taking L- arginine, up to 3 grams daily, in combination with maritime pine for 1-6 months improves a subjective assessment of sexual function when compared with control (112715). Some preliminary clinical evidence suggests that taking L-arginine orally in low doses, 1.7 grams daily in combination with maritime pine bark extract (Pycnogenol) or taking 0.69 grams daily along with maritime pine bark extract and aspartic acid (Edicare, Kobayashi Pharmaceutical Co. Ltd.) modestly improves symptoms of ED (10416,50924). Another preliminary clinical trial has investigated the effects of a combination of L-arginine 2.5 grams daily for 6 months and tadalafil 5 mg daily for 3 months, both starting with the initiation of weekly extracorporeal shock wave (ESW) therapy. When compared with ESW alone, this combination modestly improves sexual function for up to 12 months (110388). The effect of L-arginine alone is not clear from these studies.
• Hypertension. Oral L-arginine can modestly reduce systolic and diastolic blood pressure. Details: Oral L-arginine seems to have additive vasodilating effects when used with angiotensin converting enzyme (ACE) inhibitors or nitrate vasodilators such as isosorbide mononitrate (7822,20192,31916). A meta-analysis of clinical research in a variety of populations shows that taking L-arginine reduces systolic and diastolic blood pressure (SBP; DPB) by an average of 6.40 mmHg and 2.64 mmHg, respectively. Sub-analyses show that these reductions occur in both normotensive and hypertensive individuals. Beneficial effects were limited to adults with a body mass index (BMI) of 18.5 to 19.9 kg/m² (110384). The effect of L-arginine on blood pressure levels in adults exposed to traffic-related air pollution (TRAP) has also been investigated. Clinical research in adults with hypertension shows that taking L-arginine 3 grams three times daily for 2 weeks modestly reduces SBP and DBP elevations following a 2-hour exposure to TRAP during an outdoor walk compared with taking placebo (110383). Doses have included 4-24 grams daily, with the best evidence of benefit for doses of less than 9 grams daily, for 2-24 weeks (7818,10636,31871,31923,32167,32201,110383,110384).
• Necrotizing enterocolitis (NEC). Oral L-arginine may help prevent NEC in premature infants. Details: In a meta-analysis of 3 clinical trials, L-arginine 260 mg/kg orally in a single dose or two divided doses daily reduces the absolute risk of NEC in premature infants by about 62% when compared with placebo. To prevent one case of NEC, 6 infants would need to be treated with L-arginine (8474,91194,96803).
• Peripheral arterial disease (PAD). Short-term use of intravenous or oral L-arginine may improve symptoms of PAD, but long-term use does not seem to be beneficial. Details: Clinical research shows that using L-arginine intravenously or orally for up to 8 weeks increases flow-mediated dilation and improves symptoms of intermittent claudication associated with PAD (3465,31857,31905). However, long-term administration of L-arginine orally for up to 6 months does not improve walking speed, walking distance, or absolute claudication distance in patients with PAD and intermittent claudication (31957,31985).
• Pre-eclampsia. Intravenous L-arginine may have beneficial effects in pre-eclampsia. However, it is unclear if oral L-arginine is effective. Details: One small clinical study shows that intravenous L-arginine 30 grams as a one-time dose decreases systolic blood pressure (SBP) by 5 mmHg and diastolic blood pressure by 11 mmHg when compared to baseline in pregnant patients with hypertension or pre-eclampsia (31847), while intravenous L-arginine 20 grams daily for 5 days decreases SBP and DBP by about 2% when compared with placebo (31978). Another small clinical study shows that oral use of L-arginine 3 grams daily for 3 weeks reduces SBP and DBP by around 7 and 5 mmHg, respectively, when compared with placebo (31938); however, taking L-arginine 12 grams daily by mouth for 5 days does not seem to improve blood pressure in these patients (11828). Another preliminary clinical trial allowing for both oral and intravenous dosing shows that taking L-arginine 3.5 grams by mouth every 6 hours or 10 grams via intravenous infusion every 8 hours shortly before or immediately after delivery and continuing until postpartum day 3 does not improve blood pressure when compared with placebo (31959). The reasons for the disparate findings are unclear, but the small study sizes, as well as variations in the dose, duration, and timing of therapy before and/or after delivery, may explain some of the differences. Oral L-arginine has also been evaluated for the prevention of pre-eclampsia. One clinical study in patients at high risk for pre-eclampsia shows that taking L-arginine 3 grams daily starting the 20th week of gestation reduces the risk of pre-eclampsia by about 74% when compared with placebo (96811). Based on these results, one case of pre-eclampsia is prevented for every 6 high-risk pregnant patients treated with L-arginine 3 grams daily. Another clinical study also shows that taking two bars of a specific medical food (Heart Bars, Nellson Nutraceutical) containing L-arginine 6.6 grams and antioxidant vitamins daily starting at 14-32 weeks gestation and continuing until delivery reduces the risk of pre-eclampsia by 44% when compared with a bar containing antioxidant vitamins alone in patients at high risk of pre-eclampsia (91197). Based on these results, one case of pre-eclampsia is prevented for every 11 high risk patients treated with this L-arginine-containing medical food.
• Pregnancy-induced hypertension. Intravenous L-arginine may have beneficial effects in pregnancy-induced hypertension. Details: Some clinical research in patients with pregnancy-induced hypertension shows that intravenous infusion of L-arginine 20 grams daily for up to 5 days decreases systolic blood pressure by 2% to 3% and diastolic blood pressure by about 3% when compared with placebo (31933,31961,31978). Clinical research in patients with pre-existing hypertension has also been conducted. One clinical trial shows that taking L-arginine 4 grams by mouth daily for 10-12 weeks does not seem to reduce blood pressure in those with pre-existing hypertension or mild gestational hypertension. However, these results are confounded by the fact that more patients taking placebo needed to be placed on antihypertensive therapy during the study. L-arginine reduced the risk of being placed on antihypertensive drug therapy during the pregnancy by 47% when compared with placebo (32191). Based on this study, for every 5 patients with pregnancy-induced hypertension treated with L-arginine over placebo, antihypertensive drug therapy is avoided in one additional patient. L-arginine has also been investigated in combination with other ingredients in patients with pre-existing hypertension. Preliminary clinical research in patients with pre-existing hypertension and a previous history of pre-eclampsia, stillbirth, intrauterine growth restriction (IUGR), or other placenta vascular disorder shows that taking L-arginine and other ingredients starting at 14 weeks gestation prevents an increase in blood pressure and reduces the percentage of patients requiring new antihypertensive medication by about 73% compared with 24.5% of those not taking this combination. In this study, L-arginine 3 grams daily was taken with magnesium 350 mg and salicylate 100 mg. Therefore, the effect of L-arginine alone is unclear. All patients in the study were taking low dose aspirin 100 mg daily (110382).

POSSIBLY INEFFECTIVE

• Chronic kidney disease (CKD). Oral or intravenous L-arginine does not seem to improve CKD. Details: Most preliminary clinical research shows that taking L-arginine, either orally for up to 6 months or intravenously short-term, does not improve kidney function, glomerular filtration rate, or renal plasma flow in patients with CKD, although proteinuria may be reduced in some patients (31844,31904,32235,32303).
• Hypercholesterolemia. Oral L-arginine does not seem to reduce cholesterol levels. Details: Preliminary clinical research in patients with hypercholesterolemia shows that taking L-arginine 21 grams daily for 4 weeks does not reduce plasma lipids (1363). Furthermore, meta-analyses of clinical research show that taking L-arginine for up to about 6 months does not reduce total or low-density lipoprotein (LDL) cholesterol levels in populations of healthy individuals or those with cardiovascular disease risk factors. However, there was a very small effect on fasting triglyceride levels (102590,102591).
• Myocardial infarction (MI). Oral L-arginine does not seem to improve outcomes after MI. Details: Patients who have had an ST-segment MI who take L-arginine within 24 hours to 21 days, titrated up to a dose of 3 grams three times a day for up to 6 months, do not seem to have reduced vascular stiffness or increased ejection fraction (13221,32137). Also, there is some concern that long-term use of L-arginine might actually worsen outcomes and increase mortality in these patients (13221). Population studies also suggest that intake of L-arginine does not reduce the risk of experiencing an acute coronary event such as MI or coronary heart disease-related mortality (3332,6896,7821,10637).
• Tuberculosis. Oral L-arginine does not seem to improve symptoms or the clearance of tuberculosis infection. Details: Clinical research shows that taking L-arginine (ArgimaxH) 6 grams daily orally for 8 weeks, with or without vitamin D, does not improve symptoms of tuberculosis or the clearance of tuberculosis infection when used with standard treatment (91196).
• Wound healing. Oral L-arginine does not seem to improve wound healing. Details: Clinical research shows that taking L-arginine (as arginine aspartate) 17 grams orally in three divided doses daily for 2 weeks does not improve epithelialization in healthy, elderly patients with catheter wounds, although it may improve collagen deposition (32247). Also, taking L-arginine (as L-arginine hydrochloride) 26 grams daily for 5 days perioperatively does not improve angiogenesis, re-epithelialization, or neutrophil count in patients undergoing skin graft donation when compared with placebo (20692). In addition, taking a wound-specific oral nutrition supplement containing L-arginine 4.5 grams, zinc, and vitamin C twice daily for 4 weeks, along with standard wound care for 8 weeks, is no more effective for wound healing than a standard oral nutrition supplement along with standard wound care (90198). L-arginine has also been studied in combination with other ingredients. Taking L-arginine enterally or orally, before or after surgery, in combination with ribonucleic acid (RNA) and either eicosapentaenoic acid (EPA) or fish oil, seems to improve wound healing when compared with a control group (5531,32174). Another observational study conducted in Italy in newborns shows that applying a specific topical powder containing L-arginine, arnica extract, zinc oxide, and other ingredients (Cicaben, Orsana Italia S.r.l.) to the newborn's umbilical cord stump 3 to 4 times daily until stump detachment reduces the rates of mild complications 48 hours after discharge such as a wet cord stump but does not change the time to cord stump detachment or the rates of purulent secretions or umbilical granulomas when compared with standard dry care. However, no differences were noted between the groups one week after discharge (113662). The validity of these results is limited by the observational nature of the study and the ability of the parents to select a treatment group. It is unclear if the effects in these studies are due to L-arginine, other ingredients, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acute respiratory distress syndrome (ARDS). Small clinical studies suggest that oral L-arginine may prevent ARDS. Details: A meta-analysis of three small studies shows that taking L-arginine 3 grams daily, starting in the second or third trimester usually until delivery, reduces the risk of ARDS in the infant by about 54% when compared to control, including placebo or no treatment (110379).
• Altitude sickness. It is unclear if oral L-arginine is beneficial in patients with altitude sickness. Details: Preliminary clinical research shows that taking L-arginine 4 grams orally three times daily for 2 days while ascending to a high altitude and for 24 hours while at high altitude does not reduce altitude sickness when compared with placebo (31955).
• Anthracycline cardiotoxicity. Although there is interest in using oral L-arginine for anthracycline cardiotoxicity, there is insufficient reliable information about the clinical effects of L-arginine for this purpose.
• Anemia of chronic disease. It is unclear if oral L-arginine is beneficial for anemia in patients with chronic kidney disease. Details: One very small clinical study in elderly adults with chronic kidney disease and anemia shows that taking L-arginine orally 1.3 grams daily might increase hemoglobin and erythropoietin levels in some patients when compared to baseline (31988). The validity of these findings is limited by the small study size and the lack of a comparator group.
• Asthma. It is unclear if oral L-arginine is beneficial in patients with asthma. Details: Preliminary clinical research in adults with severe asthma shows that taking L-arginine 0.05 gram/kg ideal body weight twice daily does not reduce asthma exacerbations when compared with placebo (104223). This study may have been inadequately powered to detect a difference in exacerbation rates between groups. While other studies have shown adverse airway effects in patients with asthma (121,31849), this study demonstrated no change in exacerbations and reported no adverse airway effects.
• Athletic performance. Small clinical studies suggest that oral L-arginine may improve measures of athletic performance. Details: A meta-analysis of 5 small clinical trials shows that taking L-arginine seems to modestly improve measures of cardiorespiratory fitness, as measured by a 0.07 L/minute increase in maximal oxygen uptake, when compared with control (105064). L-arginine has also been examined for its effects on athletic performance. Most research suggests that taking L-arginine does not improve athletic performance. However, clinical trials are small and may not be adequately powered to detect a difference in these outcomes Taking L-arginine as a single dose of 5 or 6 grams or as 5-10 grams daily for 2-4 weeks does not improve grip strength, strength during resistance exercise, power output during cycling, or muscle function during recovery from intense resistance exercise in healthy adults (91190,97393,99265,110381,110389). Also, taking L-arginine 5 grams daily for 4 weeks (Bioarginina Farmaceutici Damor) or 8 grams daily for 8 days does not increase swim speed (110381,110386). In contrast, some research suggests that drinking a single beverage containing the same dose of L-arginine 6 grams increases the time to exhaustion during high-intensity exercise when compared with placebo (32180). Also, a meta-analysis of small clinical trials shows that supplementation with L-arginine has a large beneficial effect on aerobic performance and a small beneficial effect on anaerobic performance. However, publication bias was evident in the aerobic performance data, limiting these conclusions. Doses found to be beneficial in this analysis included an acute dose of L-arginine 0.15 gram/kg 60-90 minutes before performance or chronic dosing of 1.5 grams to 2 grams daily for 4-7 weeks for aerobic performance. The chronic dose of L-arginine most likely to be beneficial for anaerobic performance is unclear from this analysis due to inclusion of studies using arginine alpha-ketoglutarate (110395). With the exception of a few studies which include a very small number of healthy females (99265,110395,110386), research on the use of L-arginine for athletic performance has focused almost exclusively on healthy males. Also, studies are heterogeneous with respect to sport and endpoints. Therefore, whether results can be applied to females or specific athletes is unclear. L-arginine has also been evaluated in overweight males. One small clinical study shows that taking a single dose of L-arginine 6 grams 90 minutes prior to high-intensity interval training seems to improve exercise tolerance by improving ventilation, heart rate, and oxygen uptake when compared with placebo (105060). L-arginine has also been evaluated in combination with other ingredients. Research in male soccer players shows that taking L-arginine 1.2 grams and L-citrulline 1.2 grams daily for 7 days increases total power output over a 10-minute cycling test and improves subjective perceptions of exertion when compared with placebo (100956). Another study shows that taking L-arginine 1.5 or 3 grams daily, in combination with grape seed extract, increases physical working capacity at fatigue threshold when compared with pretreatment in untrained, college-aged males (32164).
• Beta-thalassemia. It is unclear if oral L-arginine is beneficial in children with beta-thalassemia. Details:Preliminary clinical research in children aged 6-18 years treated conventionally for pulmonary hypertension related to beta-thalassemia shows that taking L-arginine 0.1 mg/kg daily for 60 days reduces Doppler echocardiography pulmonary arterial pressure by 35% compared with baseline. This measurement was increased by up to 15% in children given conventional treatments only; however, a statistical comparison between these treatment groups was lacking (110391).
• Breast cancer. It is unclear if oral L-arginine is beneficial in patients with breast cancer. Details: Preliminary clinical research shows that taking L-arginine 30 grams daily for 3 days prior to chemotherapy does not improve the clinical response rate in breast cancer patients when compared with placebo (32282).
• Cognitive impairment. It is unclear if oral L-arginine is beneficial in patients with cognitive impairment. Details: A small clinical trial in frail adults aged 65 years of age and up with hypertension shows that taking L-arginine (Bioarginina) 1.66 grams twice daily for 4 weeks modestly improves cognitive function when compared to placebo (110385).
• Congestive heart failure (CHF). It is unclear if oral L-arginine is beneficial in patients with CHF. Details: One small clinical study in patients with CHF stage 2-3 shows that taking L-arginine 15 grams daily for 5 days, in combination with conventional treatment, seems to improve glomerular filtration rate (GFR), creatinine clearance, and sodium and water elimination after saline loading, indicating an improvement in kidney function (3596).
• Coronavirus disease 2019 (COVID-19). It is unclear if oral L-arginine is beneficial in patients with severe COVID-19 infection. Details: A small clinical trial in patients with severe COVID-19 shows that receiving oral L-arginine (Argin, Nutrigrow, India) 3 grams daily for a maximum of 10 days while on oxygen support does not affect the percentage of patients weaned off oxygen support after 10 days, the length of time requiring oxygen support, the duration of hospitalization, or the incidence of adverse thrombotic events, compared with placebo (110392). This study may not have been adequately powered to detect differences between groups. An interim analysis of a small clinical trial in patients hospitalized with severe COVID-19 shows that adding oral L-arginine (Bioarginina, Farmaceutici Damor) 1.66 grams twice daily to standard therapy throughout hospitalization increases the rate of respiratory support reduction by 60% after 10 days of therapy, but not after 20 days of therapy, when compared with placebo. L-arginine also significantly reduced the length of hospital stay. The median hospital stay was 25 days and 46 days, respectively, for L-arginine and placebo (106500). L-arginine has also been investigated in combination with other ingredients for post-acute COVID symptoms. Preliminary clinical research in adults with persistent fatigue following a COVID infection shows that taking L-arginine 1.66 grams plus vitamin C 500 mg (Bioarginina C, Farmaceutici Damor) twice daily for 28 days increases the distance walked in 6 minutes by 30 meters and reduces the percentage of patients with fatigue by about 89%, when compared with placebo. Grip strength was also increased (110390).
• Coronary artery bypass graft (CABG) surgery. It is unclear if oral L-arginine is beneficial for preventing complications after CABG surgery. Details: Preliminary clinical research shows that venous infusion of L-arginine hydrochloride 30 grams as a 10% solution over 15 minutes helps maintain mean arterial pressure, coronary vascular resistance, and graft blood flow when compared with a placebo infusion in patients that have undergone CABG (31840). Administering L-arginine 7.5 grams in 500 mL of cardioplegic solution also seems to reduce wedge pressure and intensive care unit stay in patients undergoing CABG; however, it does not reduce hospital stay duration or postoperative complications when compared with cardioplegic solution alone (31958,31886).
• Critical illness (trauma). Oral L-arginine has only been evaluated in combination with other ingredients; its effects when used alone are unclear. Details: A meta-analysis of clinical research shows that taking L-arginine orally with glutamine, nucleotides, and omega-3 fatty acids reduces the recovery time, the need for ventilation, and infection rates in critically ill patients, but does not reduce the risk of mortality (31853).
• Cyclosporine-induced nephrotoxicity. Although there is interest in using oral L-arginine for cyclosporine-induced nephrotoxicity, there is insufficient reliable information about the clinical effects of L-arginine for this purpose.
• Cystic fibrosis. It is unclear if oral L-arginine is beneficial in patients with cystic fibrosis. Details: Preliminary clinical research in teens and adults with cystic fibrosis shows that twice daily inhalation with L-arginine 500 mg for 2 weeks does not improve lung function when compared with inhaling 2.6% hypertonic saline twice daily (96807).
• Dental caries. Small clinical studies suggest that using a dentifrice containing L-arginine might prevent dental caries. Details: A meta-analysis of small studies shows that use of a dentifrice containing L-arginine 1.5% w/w in combination with calcium base (Dical or calcium carbonate) and fluoride 1450 ppm 2-3 times daily for up to 2 years reduces the risk of developing dental caries by a small to moderate amount when compared with a dentifrice containing only fluoride in children and adults (96806). Also, preliminary clinical research shows that using a confection containing an L-arginine complex (CaviStat) for one year reduces the number of dental caries in molars of children when compared with a sugarless mint control (32011). L-arginine has also been investigated as a prebiotic in combination with probiotics. In 5- to 9-year-old children with low caries risk, clinical research shows that taking one lozenge daily for 10-12 months containing arginine 20 mg along with Lacticaseibacillus paracasei and Lacticaseibacillus rhamnosus, modestly reduces caries severity, but does not reduce caries progression, active caries lesions, plaque, or gingivitis, when compared with placebo (113241,113242).
• Dental hypersensitivity. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that using a toothpaste containing L-arginine, calcium, and fluoride twice daily reduces dentin hypersensitivity when compared with pretreatment or control (32130,32131,32132,32177). Another moderate-sized clinical study in adults shows that applying a topical combination of L-arginine 10% and ibuprofen to tooth enamel surfaces for 10 minutes prior to in-office tooth bleaching reduces the risk and intensity of tooth sensitivity when compared with placebo (115354). It is unclear whether the effects are due to L-arginine, other ingredients, or the combination.
• Diabetes. Small, low-quality studies suggest that oral L-arginine does not improve glycemic control in people with type 2 diabetes. Details: A meta-analysis of small, low-quality studies shows that taking L-arginine 2-20 grams daily for up to 77 weeks decreases fasting blood glucose and serum insulin levels in adults without diabetes. However, no improvements occurred in adults WITH type 2 diabetes. This may be explained by previous studies which suggest L-arginine affects glucose control only in the early steps of beta-cell dysfunction. L-arginine did not improve insulin resistance or glycated hemoglobin (HbA1c) in patients with or without diabetes (104225). Also, a prospective observational study in patients with type 1 or type 2 diabetes has found that taking a specific product (Flebotrofine, AMNOL Chimica Biologica) containing L-arginine for 3 months is not associated with improvements in HbA1c, cholesterol, or triglyceride levels when compared with baseline. Other ingredients in this product included diosmin, troxerutin, hesperidin, black currant extract, and gotu kola extract (108151). The validity of these findings is limited by the lack of a comparator group.
• Diabetic foot ulcers. It is unclear if oral or subcutaneous L-arginine is beneficial in patients with diabetic foot ulcers. Details: A very small clinical study shows that administering L-arginine subcutaneously at the site of diabetic foot ulcers does not decrease healing time or rate of amputation when combined with conventional therapies (14914). Also, taking a specific drink containing L-arginine 7 grams, L-glutamine 7 grams, and calcium hydroxymethylbutyrate (HMB) 1.5 grams (Juven/Abound, Abbott Nutrition) orally twice daily for 16 weeks does not improve diabetic foot ulcer healing when compared with a control drink in non-ischemic patients or those with normal albumin levels. However, in specific populations with low albumin and/or poor limb perfusion, up to 74% more patients had total wound healing when compared with the control drink (96637).
• Diabetic neuropathy. It is unclear if oral L-arginine is beneficial in patients with diabetic neuropathy. Details: Preliminary clinical research shows that taking L-arginine 3 grams daily for 3 months does not improve circulation, disability, or nerve function in patients with diabetic neuropathy when compared with placebo (32145).
• Head and neck cancer. It is unclear if oral L-arginine is beneficial in patients with head and neck cancer. Details: Small clinical studies suggest that enteral nutrition supplemented with L-arginine does not seem to have any beneficial effects on markers of immune function such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), length of postoperative hospital stay, or fistula rates; however, it seems to reduce wounds and general infections after surgery in patients with head and neck cancer when compared with control (10160,32008).
• Heart failure. It is unclear if oral L-arginine is beneficial in patients with heart failure. Details: Preliminary clinical research in adults with heart failure shows that taking L-arginine 3.0-12.6 grams orally daily for 6-12 weeks does not consistently improve exercise tolerance or peripheral vascular resistance (3595,6028,32138). However, some research shows that taking L-arginine 1000 mg three times daily for 10 weeks modestly improves measures of cardiac function compared with placebo (110380). Although some research disagrees (32138), most research shows that taking L-arginine modestly improves quality of life (3595,110380).
• Heart transplant complications. It is unclear if oral L-arginine is beneficial in patients that have received a heart transplant. Details: Preliminary clinical research shows that taking L-arginine 6 grams orally twice daily for 6 weeks increases walking distance and oxygen uptake and delays the ventilatory threshold in heart transplant patients when compared with baseline (32150).
• HIV/AIDS-related wasting. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical study in patients with HIV/AIDS shows that taking L-arginine orally, in combination with hydroxymethylbutyrate (HMB) and glutamine for 8 weeks, increases body weight, particularly lean body mass, and positively affects immune status when compared with placebo (1909). However, other clinical research in HIV-positive patients shows that taking L-arginine 7.4 grams daily orally, in combination with omega-3 fatty acids and a balanced oral nutritional supplement for 6 months, does not improve body weight or fat mass, total energy intake, or immune status when compared to taking the nutritional supplement alone (113).
• Impaired glucose tolerance (prediabetes). It is unclear if oral L-arginine can prevent the development of type 2 diabetes in adults with prediabetes. Details: Clinical research shows that taking L-arginine (Bioarginine, Farmaceutici Damor) 3.2 grams orally twice daily for 18 months does not reduce the incidence of diabetes in patients with impaired glucose tolerance (prediabetes). However, when assessed one year after treatment discontinuation, patients who took L-arginine had a 58% lower risk of developing diabetes when compared with placebo (91195).
• Infertility. It is unclear if oral L-arginine improves outcomes in people undergoing an assisted reproductive technology (ART) program. Details: Some preliminary clinical research shows that taking L-arginine 16 grams daily decreases the cancellation rate of in vitro fertilization (IVF) and increases the number of oocytes collected in females undergoing an ART program when compared with control. However, taking L-arginine does not seem to improve the number of viable pregnancies (31842). A small clinical study of females undergoing an ART program shows that taking a combination product containing L-arginine 1 gram with folate 200 mcg or L-arginine 2 grams, folate 400 mcg, and vitamin E 10 mg daily for 12 weeks does not affect the hCG-positive rate or clinical pregnancy rate when compared with placebo. A subgroup analysis suggests that taking these combination products might improve HCG-positive and clinical pregnancy rates in females who are undergoing ART due to male infertility (104224). However, this small study was not adequately powered to detect a difference in these outcomes, limiting the validity of these findings.
• Interstitial cystitis. Small clinical studies suggest that oral L-arginine may improve pain in interstitial cystitis. Details: Taking L-arginine orally seems to reduce some symptoms, especially pain, that are associated with interstitial cystitis (107,114,3460,31855,32267). Research shows that patients with interstitial cystitis having a bladder capacity greater than 800 mL and/or a history of recurrent genitourinary infections might respond more favorably to L-arginine than patients with bladder capacity less than 800 mL and/or no history of recurrent genitourinary infections. Three months of treatment may be necessary before significant symptom improvement occurs (3460). However, L-arginine does not seem to reduce the need to urinate at night or improve urgency or frequency of urination (3460,31855).
• Intrauterine growth restriction (IUGR). Small clinical studies suggest that oral or intravenous L-arginine may increase birthweight in IUGR. Details: A meta-analysis of mainly small studies shows that L-arginine given orally or intravenously in the third trimester for a time period of 7 days or until delivery increases the birthweight by up to 650 grams in patients with an IUGR pregnancy. Furthermore, there is evidence from a small number of these studies that L-arginine supplementation decreases the risk of neonatal respiratory distress syndrome and fetal intracranial hemorrhage (96804). A more recent meta-analysis of small studies also shows that taking L-arginine 3 grams daily, starting in the second or third trimester usually until delivery, reduces the risk of an IUGR infant by about 32% when compared to control, including placebo or no treatment (110379). Doses used in clinical research have usually been 3 grams daily orally, although some studies have used up to 20 grams intravenously (31930,31937,96804,110379). However, supplementation with L-arginine does not seem to increase birthweight or reduce neonatal mortality or morbidity when compared with placebo in patients with severe IUGR (32083).
• Kidney transplant. Small clinical studies suggest that oral L-arginine may not improve kidney function in patients after kidney transplantation. Details: Although preliminary clinical research showed some benefit, evidence from other clinical research shows that infusion with L-arginine does not increase renal plasma flow or glomerular filtration rate in kidney transplant patients treated with cyclosporine, including those experiencing transplant dysfunction (112,31876,32229). Other evidence suggests that intravenous L-arginine improves kidney function only in transplant patients receiving organs with a short cold ischemia time or those receiving kidneys from young donors (31887).
• Male infertility. It is unclear if oral L-arginine is beneficial in males with infertility. Details: Preliminary clinical research shows that taking L-arginine 4 grams daily for 12 weeks does not improve semen quality in males with oligospermia when compared with placebo (32209). However, one small clinical study shows that a specific formulation of L-arginine aspartate and maritime pine bark extract (Prelox), taken for 6 months, improves sperm quality in males with idiopathic male infertility when compared to baseline (32061). The validity of this finding is limited by the lack of a comparator group. Additionally, it is unclear if this effect is due to L-arginine, maritime pine bark, or the combination.
• Mitochondrial myopathies. Small clinical studies suggest that intravenous L-arginine may modestly improve symptoms in patients with MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes syndrome). Details: Preliminary clinical research shows that infusions of L-arginine, 0.5 grams/kg administered within one hour of stroke-like symptoms, improves headaches, nausea, vomiting, transient blindness, and the appearance of bright spots when compared to pretreatment in patients with MELAS (31943,99263). Also, taking oral L-arginine 4-24 grams daily for 18 months seems to reduce the frequency and severity of stroke-like symptoms associated with MELAS when compared to baseline (31943). However, other preliminary clinical research shows that taking oral L-arginine 0.3-0.5 grams/kg daily in three divided doses for 2 years does not reduce the severity of MELAS symptoms, including migraine and stroke-like episodes. If a stroke-like episode did occur, administration of intravenous L-arginine 0.5 grams/kg improved headache, nausea, vomiting, and visual disturbance (99263). The validity of this research is limited by the small study sizes and the absence of comparator groups.
• Migraine headache. Although there is interest in using oral L-arginine for migraine, there is insufficient reliable information about the clinical effects of L-arginine for this condition.
• Muscular dystrophy. There is limited evidence on the oral use of L-arginine in patients with Duchenne muscular dystrophy. Details: A very small study in five children with Duchenne muscular dystrophy, shows that drinking a beverage containing L-arginine hydrochloride (L-Arginine Hydrochloride, Selectchemie) 2.5 grams three times daily, in addition to metformin 250 mg twice daily, for 16 weeks improves motor function by 4% and increases distance walked in two minutes by 9.6 meters when compared to baseline (96805). The validity of these findings is limited by the very small study size and lack of a comparator group.
• Nitrate tolerance. It is unclear if oral L-arginine is beneficial for nitrate tolerance. Details: A very small crossover study in adults with stable angina shows that taking L-arginine orally 700 mg four times daily for up to 10 days seems to prevent tolerance to transdermal nitrate when compared with placebo (8475).
• Obesity. Small clinical studies suggest that oral L-arginine may be beneficial for weight loss. Details: A meta-analysis of mainly small clinical trials shows that taking L-arginine daily for at least 8 weeks modestly reduces body weight, body mass index (BMI), and waist circumference when compared with placebo. However, when taking L-arginine for less than 8 weeks, BMI and body weight were not affected. The optimal dose of L-arginine was 2-6 grams (110398). An additional small clinical study suggests that taking a specific arginine supplement (NOW Foods) 3 grams by mouth three times daily for 12 weeks, in addition to receiving dietary counseling, reduces waist circumference by 4-6 cm and reduces body weight by 1.8-2.9 kg when compared to baseline in obese females 18-40 years of age (91193). The validity of these findings is limited by the lack of a comparator group.
• Oral mucositis. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study shows that taking a specific combination of L-arginine 7 grams, L-glutamine 7 grams, and hydroxymethylbutyrate (HMB) 1.2 grams (Abound; Abbott) in water twice daily during chemoradiotherapy treatment for head and neck cancer does not reduce the incidence of severe oral mucositis when compared with a historical control (99243). The validity of this finding is limited by the lack of a placebo control. Additionally, a small open-label study in patients undergoing chemoradiation for head and neck cancer shows that taking a specific combination product (Abound, Abbot) containing L-arginine, glutamine, and HMB twice daily throughout chemoradiation treatments decreases the incidence of grade 3 or higher oral mucositis and ameliorates body weight loss when compared with no intervention (113726). However, the incidence of grade 2 or higher oral mucositis was not reduced. It is unclear if this effect is due to L-arginine, other ingredients, or the combination. Additionally, the validity of the study is limited by the lack of blinding.
• Periodontitis. It is unclear if oral L-arginine is beneficial in patients with periodontitis. Details: Preliminary clinical research in patients with chronic periodontitis shows that using L-arginine aspartate (Yuria-Pharm, Ukraine) 1 gram three times daily orally for 10 days after scaling and root planing, modestly reduces bleeding on probing but not periodontal pocket depth, when compared with untreated controls (108926).
• Physical performance. It is unclear if oral L-arginine is beneficial for improving physical performance in older adults. Details: A small study in physically active females 65 years of age and older shows that taking L-arginine 8 grams as a single dose does not improve lower body strength, measured by knee flexion and extension tests, or functional performance, measured by sit-stand, tandem gait, and timed up-and-go tests, when compared with placebo (96812).
• Polycystic ovary syndrome (PCOS). Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a combination of N-acetylcysteine 1200 mg daily plus L-arginine 1600 mg daily for 6 months modestly improves menstrual function and decreases insulin resistance in patients with PCOS when compared to baseline (32094). The validity of these findings is limited by the lack of a comparator group.
• Postoperative infection. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Small clinical studies show that taking L-arginine, enterally or orally, either before or after surgery, in combination with fish oil, or with ribonucleic acid (RNA) and eicosapentaenoic acid (EPA), seems to reduce the rate of perioperative infection when compared with a control group. The risk of infection was 41% lower when compared to taking no arginine-based formulations. However, there is no good evidence to support the use of L-arginine alone for this purpose, and it is possible that this effect is due to the other ingredients or the combination of ingredients (5531,32174,32196).
• Postoperative recovery. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Small clinical studies show that taking L-arginine, enterally or orally, either before or after surgery, in combination with fish oil, or with ribonucleic acid (RNA) and eicosapentaenoic acid (EPA), seems to reduce the recovery time after surgery or serious illness when compared with a control group. This seems to be related to a reduced number of perioperative infections and improved wound healing. However, there is no good evidence to support the use of L-arginine alone for this purpose, and it is possible that this effect is due to the other ingredients or the combination of ingredients (5531,32174,32196). The effect of another combination product containing L-arginine is unclear. In one clinical study, taking a combination product (Abound, Abbott) containing L-arginine 7 grams, glutamine 7 grams, and hydroxymethylbutyrate 1.2 grams orally daily for 3 days before and 7 days after abdominal surgery did not reduce the incidence of wound infection or other complications when compared with placebo (99413). However, when a similar combination of L-arginine 14 grams, glutamine 14 grams, and hydroxymethylbutyrate 3 grams (Heallagen) was taken orally daily for one month before heart surgery, the length of hospital and ICU stay were reduced by about one day. Recovery, based on some but not all biochemical or other measurements, was also improved. However, there was no difference in risk of overall postoperative complications (110394). The discrepancies between these two studies may be related to differences in the dose or duration of the combination product and/or the type of surgery.
• Pressure ulcers. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Oral L-arginine has been evaluated in combination with other ingredients for the treatment of grade II-IV pressure ulcers. Two small clinical studies in hospitalized patients show that administering an oral nutritional supplement enriched with L-arginine, zinc, and vitamin C improves ulcer healing when compared with a standard diet (31953,87173). A small preliminary clinical study in sedentary older adults in care facilities shows that giving an oral or enteral combination of L-arginine 7.4 grams, L-glutamine 7.4 grams, and hydroxymethylbutyrate (HMB) 1.3 grams (Abound, Abbott) daily for 20 weeks reduces median time to healing by 48 days when compared with standard care only (110396). Also, preliminary clinical research in patients living in long-term care facilities with grade II-IV pressure ulcers shows that taking an oral nutritional supplement enriched in protein, energy, L-arginine, vitamin C, and zinc daily for 9 weeks reduces ulcer area and decreases oozing when compared to baseline (32045). The validity of this finding is limited by the lack of a comparator group.
• Preterm labor. Small clinical studies suggest that oral L-arginine may prevent preterm labor. Details: A meta-analysis of three small studies shows that taking L-arginine 3-6.6 grams daily, starting in the second or third trimester usually until delivery, reduces the risk of preterm labor by about 50% when compared to control, usually placebo (110379).
• Pulmonary hypertension. It is unclear if oral L-arginine is beneficial in children with pulmonary hypertension related to beta-thalassemia. Details: Preliminary clinical research in children aged 6-18 years treated conventionally for pulmonary hypertension related to beta-thalassemia shows that taking L-arginine 0.1 mg/kg daily for 60 days reduces Doppler echocardiography pulmonary arterial pressure by 35% compared with baseline. This measurement was increased by up to 15% in children given conventional treatments only; however, a statistical comparison between these treatment groups was lacking (110391).
• Radiation dermatitis. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with head and neck cancer shows that taking a combination of L-arginine 7 grams, L-glutamine 7 grams, and hydroxymethylbutyrate (HMB) 1.2 grams (Abound, Abbott) in water twice daily from the first day of radiation to approximately 1 week after completion does not reduce the number of patients with severe dermatitis when compared with taking no supplement. However, there was a 34% reduction in the incidence of moderate dermatitis and the overall duration of dermatitis was reduced (96639).
• Restenosis. It is unclear if intravenous L-arginine helps to prevent restenosis after stent implantation. Details: Some clinical research suggests that intravenous and intracoronary infusion of L-arginine during stent implantation followed by oral L-arginine for 2 weeks does not reduce the risk of restenosis when compared with placebo (31925). However, local delivery of 6 mL of L-arginine 100 mg/mL for 15 minutes after stent deployment seems to reduce neointimal formation at 6 months after stent placement when compared with placebo (31883).
• Respiratory tract infections. Although there is interest in using oral L-arginine for respiratory tract infections, there is insufficient reliable information about the clinical effects of L-arginine for these conditions.
• Schizophrenia. It is unclear if oral L-arginine is beneficial in patients with schizophrenia. Details: A small clinical study shows that taking L-arginine 3 grams twice daily for 3 weeks, in conjunction with an individualized medication regimen, does not improve positive, negative, or depressive symptoms associated with schizophrenia when compared with taking the medication regimen alone (99264).
• Sexual dysfunction. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in females with sexual dysfunction who are taking oral contraceptives shows that taking a specific combination product (Lady Prelox, Horphag Research) containing L-arginine, maritime pine bark extract, L-citrulline, and rose hip extract daily for 8 weeks improves symptoms of sexual dysfunction by 18% when compared with a control group (91963). Taking the same product in a dose of 2 tablets twice daily for 8 weeks, in addition to the lifestyle management program, improves vaginal dryness in pre- and post-menopausal patients when compared with lifestyle management alone (103611). It is unclear if this effect is due to L-arginine, the other ingredients, or the combination.
• Sickle cell disease. Small clinical studies suggest that oral or intravenous L-arginine may modestly improve complications in patients with sickle cell disease. Details: Two small clinical studies in hospitalized children aged 3-19 years with sickle cell disease-related veno-occlusive crisis shows that administering L-arginine intravenously or orally 100 mg/kg three times daily for 5 days or until discharge reduces total opioid use by 26% to 54%, pain scores at discharge by 23%, and median length of hospital stay by about 36 hours when compared with placebo (97392,105063). Another very small clinical study in patients aged 13-63 years with sickle cell disease shows that taking L-arginine 0.1 grams/kg orally three times daily for 5 days reduces pulmonary hypertension when compared to baseline (11428).
• Stress. Oral L-arginine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in healthy adults shows that taking a single dose of L-arginine 50 mg plus L-theanine 200 mg modestly reduces stress associated with a stress-loading test when compared with placebo, but was no more effective than taking L-theanine alone (110393).
• Valproic acid-induced toxicities. Although there is interest in using intravenous L-arginine for valproic acid toxicity, there is insufficient reliable information about the clinical effects of L-arginine for this purpose. More evidence is needed to rate L-arginine for these uses.

(Read more about L-ARGININE)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related testosterone deficiency. It is unclear if oral maca is beneficial for age-related testosterone deficiency. Details: A moderate-size clinical study in eugonadal males age 65 years on average with symptoms related to late-onset hypogonadism shows that taking maca 1.66 grams three times daily for 12 weeks improves physical, sexual, and psychological symptom scores when compared with placebo. However, maca did not lead to a significant difference in testosterone levels between groups (112012). The interpretation of these findings is limited by the use of patient-reported outcomes.
• Amenorrhea. Although there has been interest in using oral maca for amenorrhea, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Anemia of chronic disease. Although there has been interest in using oral maca for anemia of chronic disease, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Antidepressant-induced sexual dysfunction. It is unclear if oral maca is beneficial in patients with sexual dysfunction due to antidepressants. Details: Preliminary clinical research shows that taking maca 1.5 grams twice daily for 12 weeks modestly increases remission rates in females experiencing antidepressant-induced sexual dysfunction (90278).
• Athletic performance. It is unclear if oral maca is beneficial for athletic performance. Details: A small clinical study in male elite athletes shows that taking maca 2500 mg twice daily for 8 weeks may improve some measures of physical performance, including grip strength, power, or agility, when compared to baseline (112014). However, the interpretation of this study is limited by the lack of a control group, inconsistent results among the various types of athletes included in the study, and unreported habitual activities, such as diet, that may confound results.
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral maca for CFS, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Depression. Although there has been interest in using oral maca for depression, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Fatigue. Although there has been interest in using oral maca for fatigue, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Leukemia. Although there has been interest in using oral maca for leukemia, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Male infertility. It is unclear if oral maca is beneficial for male infertility. Details: Clinical research shows that taking a specific maca product (Maca Gelatinizada La Molina, Laboratorios Hersil) 1.5-3 grams daily for 4 months increases semen volume, sperm count, and sperm motility in healthy males aged 22-44 years (18289). Conversely, a meta-analysis of 2 small clinical studies in males with infertility shows that taking 2-2.8 grams of maca daily for 12-16 weeks does not improve the concentration of semen when compared with placebo (112011). However, the interpretation of this finding is limited by the heterogeneity of the included studies.
• Memory. Although there has been interest in using oral maca for memory, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Osteoporosis. Although there has been interest in using oral maca for osteoporosis, there is insufficient reliable information about the clinical effects of maca for this purpose.
• Postmenopausal conditions. It is unclear if oral maca is beneficial for postmenopausal conditions. Details: Two small clinical trials show that taking powdered maca (Maca Power, Incan Food, Healthychoices) 3.3 or 3.5 grams daily as a single dose or in two divided doses for 6 weeks modestly reduces anxiety, depression, and sexual dysfunction when compared with placebo (90606,99792). However, these changes are generally small and of questionable clinical significance (90606).
• Sexual desire. It is unclear if oral maca improves male sexual desire; it has not been evaluated for female sexual desire. Details: Preliminary clinical research shows that taking a specific maca product (Maca Gelatinizada La Molina, Laboratorios Hersil), 1.5-3 grams daily in three divided doses for 12 weeks can increase subjective feelings of sexual desire in healthy males aged 21 to 57 years (9928).
• Tuberculosis. Although there has been interest in using oral maca for tuberculosis, there is insufficient reliable information about the clinical effects of maca for this purpose. More evidence is needed to rate maca for these uses.

(Read more about MACA)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Erectile dysfunction (ED). Preliminary clinical research in middle-aged men with ED shows that taking two capsules of a specific combination product (Revactin, MD Concepts LLC) containing muira puama, ginger root, guarana, and L-citrulline twice daily for 3 months improves scores related to erectile function and intercourse satisfaction, but does not improve sexual desire or orgasmic function scores, when compared to baseline (103224). This study is limited by the lack of a placebo control, the use of per-protocol analysis, and a high dropout rate. In fact, 44% of patients withdrew in order to resume use of phosphodiesterase type 5 (PDE5) inhibitors. Further, it is unclear if these effects are due to muira puama, other ingredients, or the combination.
• Sexual dysfunction. Preliminary clinical research in women with a low sex drive shows that taking 2-6 tablets of a specific combination product (Herbal vX) containing muira puama extract (HV-430) 350-1050 mg and ginkgo extract 32-96 mg modestly improves sexual desire and the frequency of sexual intercourse when compared with baseline (63920). The lack of control group limits the validity of these findings. Further, it is unclear if these effects are due to muira puama, ginkgo, or the combination. More evidence is needed to rate muira puama for these uses.

(Read more about MUIRA PUAMA)

LIKELY EFFECTIVE

• Coronary heart disease (CHD). A diet high in soluble fiber, such as that found in oats, reduces the risk of CHD. Details: Clinical research shows that a diet containing foods high in fiber, such as oats, oat bran, or whole oat flour, reduces the risk of CHD (2737,4960,4962,4963,4964,4965,4966,4967,4968). In 1993, the US Food and Drug Administration (FDA) approved a health claim stating that consuming at least 3 grams of soluble fiber per day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of CHD (102336). However, clinical studies show that at least 3.6 grams of soluble fiber daily is needed to reduce the risk of CHD (5786,5787,5788,5794,5795,5796).
• Dyslipidemia. A diet rich in soluble fiber, such as that found in oats, can reduce cholesterol by a moderate amount. Details: Oats, oat bran, and other soluble fibers can modestly reduce total and low-density lipoprotein (LDL) cholesterol, especially when consumed as part of a diet low in saturated fat. Consuming 56-150 grams of whole oat products such as oatmeal and oat bran, containing 3.6-10 grams of soluble fiber daily, can significantly lower total and LDL cholesterol levels. For each gram of soluble fiber consumed, total cholesterol decreases by about 1.4 mg/dL and LDL by about 1.2 mg/dL. Eating 3-10 grams of soluble fiber daily can reduce total cholesterol by about 4-14 mg/dL (4976,4977,5786,5788,5792,5794,5795,8521,107749,113488,113495). For example, eating 3 bowls of oatmeal (28 gram servings) daily, providing a total of 3 grams of soluble fiber daily, can decrease total cholesterol by about 5 mg/dL (5788). However, consuming more than 10 grams of soluble fiber daily doesn't seem to increase effectiveness (5788). A meta-analysis comparing the effects of oats and isolated beta-glucans shows that both products similarly impact lipid profiles, suggesting that the bioactive component of oats are beta-glucans (113488). Oat bran products, such as oat bran muffins and oat bran flakes, may vary in their ability to lower cholesterol, depending on the total soluble fiber content and other dietary variables (6188). Whole oat products might be more effective for lowering LDL and total cholesterol than foods containing oat bran plus soluble fiber (10145). Although oats are shown to lower total and LDL cholesterol, a meta-analysis and a small clinical study in adults with and without dyslipidemia shows that consuming oatmeal or oat products does not reduce triglycerides or increase high-density lipoprotein (HDL) cholesterol when compared with controls (113488,113495).

POSSIBLY EFFECTIVE

• Diabetes. A diet rich in whole grains, such as oats, may help prevent diabetes or improve blood glucose control in patients with type 1, type 2, or gestational diabetes. Details: Population research shows that for every 16 gram daily serving of whole grains, including oats, there is a 7% to 11% lower risk of developing type 2 diabetes (100622). There is also evidence that consuming oats can decrease blood glucose and insulin levels, as well as lipid levels, in patients with diabetes. The glycemic effects of oats depend on the level of processing of the oat products. Consuming intact oat kernels or thick-cut oats (>0.6 mm) reduces postprandial blood glucose and insulin, but consuming thin-cut, or "quick", oats has no effect (105536). Clinical research shows that consuming oats and oat bran for 4-8 weeks decreases pre-prandial blood glucose, 24-hour plasma glucose, glycated hemoglobin (HbA1c), insulin levels, and low-density lipoprotein (LDL) cholesterol in people with type 2 diabetes (4980,4982,6266,103345). Various doses have been used, including 3 grams of soluble fiber daily, or bread providing 34 grams of total fiber daily (9 grams of soluble fiber) (4961,4980). Additional clinical research in obese adults with type 2 diabetes shows that eating whole grain oats 50-100 grams daily in place of other carbohydrates reduces postprandial blood glucose by 19-27 mg/dL when compared with other carbohydrates in a healthy diet. After 1 year, the groups consuming 50 grams and 100 grams of oats had an additional 0.48% and 0.64% reduction in HbA1c, respectively, when compared with the regular healthy diet group (97520). There is also some evidence that consuming oats 50 grams daily, containing 25 grams of soluble fiber, might be more effective for improving glycemic control and decreasing hyperinsulinemia than the standard moderate fiber diet recommended by the American Diabetes Association (ADA) (6266). Oats have also been evaluated in adolescents with type 1 diabetes. One very small clinical study shows that taking 50 grams of a specific oat product (Betaglucare), providing beta-glucans 6 grams, in three divided doses daily for one week is beneficial for glycemic control and variability when compared with a standard diet without beta-glucans or with taking only 25 grams of the product daily. Maximal, mean, and pre- and post-meal blood glucose levels were modestly lower, and minimal blood glucose levels were modestly higher. Most measures of glycemic variability were statistically different, although there were no differences in the duration of hypoglycemia or hyperglycemia between groups (105261). Oats have also been evaluated in patients with gestational diabetes. A randomized, controlled trial shows that taking 30 grams of a specific oat bran product (OAB; Golden Light Cup Company) orally twice daily at lunch and dinner for 4 weeks improves mean fasting blood glucose and two-hour postprandial glucose when compared with a control group. After 4 weeks, the mean fasting blood glucose and 2-hour postprandial glucose in the treatment group were 85 mg/dL and 104 mg/dL, respectively, compared with 93 mg/dL and 117 mg/dL, respectively, in the control group (107751). The validity of this study is limited by the short treatment duration and lack of follow-up.
• Gastric cancer. A diet rich in soluble fiber, such as that found in oats, might reduce the risk of gastric cancer. Details: Observational research has found that consuming a diet that includes cereal fiber, such as oats and oat bran, might reduce the incidence of gastric cancer (10435).

POSSIBLY INEFFECTIVE

• Colorectal cancer. Regular consumption of oats does not seem to reduce the risk of colorectal cancer. Details: Observational research has found that consuming oat bran or oats orally doesn't seem to reduce the risk of colon cancer. Additionally, consuming fiber, including oat-bran fiber, is not associated with a reduction in the risk for recurrence of colorectal adenomas (4820,5104).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there is interest in using topical oats for acne, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Anxiety. Although there is interest in using oral oats for anxiety, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Atopic dermatitis (eczema). Topical colloidal oatmeal cream may be beneficial in patients with atopic dermatitis. Details: Preliminary clinical research shows that applying a cream containing colloidal oatmeal 1% daily for 2 weeks moderately reduces the severity of atopic dermatitis when compared with baseline (103344). The validity of this finding is limited by the lack of a comparator group. Other research suggests that colloidal oatmeal may be beneficial when used in combination with topical steroids. Clinical research shows that the benefits obtained from applying an ointment containing fluocinolone 0.025% to the hands for 2 weeks were better maintained in the patients who also used a cream containing colloidal oatmeal 1% during this time period and for an additional 4 weeks when compared with patients using fluocinolone and the cream base without colloidal oatmeal. Quality of life was also improved in the patients using colloidal oatmeal (103340).
• Breast cancer. Observational research suggests that regular oatmeal intake may be associated with reduced mortality from breast cancer. Details: Population research in postmenopausal patients has found that those who have eaten 50 grams of oatmeal daily prior to a breast cancer diagnosis have a 20% reduced risk of all-cause mortality in the 7 years following the diagnosis when compared with patients who have not eaten oatmeal. However, no benefit was seen when post-diagnostic oatmeal intakes were examined (103343).
• Burns. Although there is interest in using topical oats for burns, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Chronic fatigue syndrome (CFS). Although there is interest in using oral oats for CFS, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Cognitive function. It is unclear if oral oats are beneficial in healthy adults with mild memory impairment. Details: Preliminary clinical research in healthy middle-aged adults with self-reported memory decline shows that consuming a specific wild green-oats extract (Neuravena, Frutarom) 800 mg as a single dose improves overall speed, but not overall accuracy, of cognitive performance when compared with placebo. However, a higher dose of 1600 mg was ineffective (97519).
• Dry skin. It is unclear if applying lotion containing colloidal oat extract improves dry skin to a greater extent than other lotion products. Details: Preliminary clinical research shows that applying a lotion containing colloidal oat extract (Aveeno Active Naturals Skin Relief 24Hr Moisturizing Lotion, Johnson & Johnson) twice daily for 2 weeks improves itchiness, cracking, scaling, dryness, and roughness when compared to baseline in females with dry skin (91458). Additional preliminary clinical research shows that applying a colloidal oatmeal lotion to the legs twice daily for three weeks reduces skin dryness and improves skin integrity when compared to baseline in adults with dry skin (97518). The validity of these findings is limited by the lack of a comparator group.
• Exercise-induced muscle soreness. It is unclear if oral oats are beneficial for exercise-induced muscle soreness. Details: A small clinical trial shows that eating two cookies containing oat flour 60 grams daily for 8 weeks reduces muscle soreness 48 or 72 hours after downhill running when compared with baseline (103341).
• Fat redistribution syndrome. It is unclear if oral oats are beneficial for fat redistribution syndrome. Details: Consumption of a high fiber diet, including oats, with adequate energy and protein might prevent fat deposition in patients with HIV. A one-gram increase in total dietary fiber may decrease the risk of fat deposition by 7% (12517).
• Gallbladder disease. Although there is interest in using oral oats for gallbladder disease, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Hypertension. It is unclear if oral oats are beneficial for hypertension. Details: A meta-analysis of 21 clinical studies in healthy adults and those with a variety of metabolic conditions including hypertension shows that consumption of oat products reduces systolic blood pressure (SBP) by 3 mmHg but has no effect on diastolic blood pressure (DBP) when compared with control. Subgroup analysis suggests that consuming oat products reduces SBP by 10 mmHg in patients with hypertension at baseline. An additional subgroup analysis suggests that consuming at least 5 grams of beta-glucan-enriched oats daily or consuming oats for a duration at least 8 weeks reduces SBP and DBP (113494). Observational research has found that consumption of oats as oatmeal or oat cereal does not seem to reduce DBPor SBP in males with minor elevations in blood pressure or patients with dyslipidemia (2956,113495). A randomized, controlled trial in patients with stage 1 hypertension receiving dietary guidance shows that taking 30 grams of oat bran, providing 8.9 grams of dietary fiber, once daily with breakfast or in between meals for 3 months improves various blood pressure measures when compared with dietary guidance alone. After 3 months of treatment, 24-hour maximum SBP and DBP decreased by 14 mmHg and 11 mmHg, respectively, and office SBP and DBP decreased by 15 mmHg and 10 mmHg, respectively. Oat consumption may also have impacted antihypertensive medication use. Two patients in the control group increased doses of antihypertensive medications, whereas 6 patients in the treatment group decreased doses and 1 patient discontinued use (107750). The effect of oral oat bran on patients with stage 2 hypertension or pre-hypertension is unknown.
• Irritable bowel syndrome (IBS). Although there is interest in using oral oats for IBS, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Metabolic syndrome. Limited research suggests that oats may not be beneficial for metabolic syndrome. Details: Preliminary clinical research in adults with metabolic syndrome shows that adding oat bran 40 grams daily for 6 weeks to a low-calorie diet does not reduce the incidence of metabolic syndrome. Oat bran also does not improve body weight, blood pressure, low-density lipoprotein (LDL) cholesterol, triglycerides, or blood glucose levels when compared with a low-calorie diet alone in patients with metabolic syndrome (103342).
• Osteoarthritis. Although there is interest in using oral oats for osteoarthritis, there is insufficient reliable information about the clinical effects of oats for this condition.
• Pruritus. Applying oat lotion topically may improve some types of pruritus. Details: Preliminary clinical research shows that applying an oat lotion (Espanol) twice daily for up to 2 weeks can decrease itching intensity by about 20% when compared to baseline in patients with pruritus associated with chronic kidney disease (uremic pruritus). This decrease is similar to the effects of applying vinegar 5% solution or taking hydroxyzine 10 mg orally. However, applying the oat lotion does not appear to decrease the frequency of itching (91457).
• Psoriasis. Although there is interest in using topical oats for psoriasis, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Rheumatoid arthritis (RA). Although there is interest in using oral oats for RA, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Stroke. It is unclear if oral oats are beneficial for reducing the risk of stroke. Details: Population research suggests that consuming oatmeal for breakfast once weekly might reduce the incidence of stroke by a small amount when compared with consuming white bread or eggs for breakfast (103337).
• Ulcerative colitis. Oral oats have only been evaluated in combination with other ingredients; their effect when used alone is unclear. Details: Preliminary clinical research shows that taking a specific oat-based product (Profermin, Nordisk Rebalance) containing fermented oat flour, Lactobacillus plantarum, barley malt flour, and lecithin, 250 mL orally twice daily for 8 weeks, reduces disease activity and increases remission in about two-fold more patients with relapsing ulcerative colitis, when compared with treatment with a specific nutritional beverage (Fresubin Original, Fresenius Kabi) (90271).
• Wound healing. Although there is interest in using topical oats for wound healing, there is insufficient reliable information about the clinical effects of oats for this purpose. More evidence is needed to rate oats for these uses.

(Read more about OATS)

POSSIBLY EFFECTIVE

• Transurethral resection of the prostate (TURP). Saw palmetto 320 mg daily seems to improve outcomes after TURP surgery in a dose-dependent manner. Details: Clinical research shows that taking saw palmetto (Permixon, Pierre Fabre Medicament) 320 mg daily for 2 months prior to TURP surgery reduces blood loss, the duration of surgery, the development of intraoperative complications, the duration of catheterization, and the length of hospitalization when compared with placebo (73323,73353). Although these studies found benefit, a small study using a lower dose of saw palmetto (Prostagood Mono, Abdi Ibrahim) 160 mg orally once daily for 5 weeks prior to TURP did not find any decrease in the risk of perioperative hemorrhage, or the density of prostate tissue (17202).

POSSIBLY INEFFECTIVE

• Benign prostatic hyperplasia (BPH). Although individual study results are conflicting, the overall body of evidence suggests that saw palmetto does not offer clinically meaningful improvements in BPH-related symptoms. Details: Research on the use of saw palmetto for improving symptoms of BPH is inconsistent and contradictory. To date, the best available evidence addressing the effectiveness of saw palmetto in patients with BPH comes from two high-quality clinical trials sponsored by the National Institutes of Health (NIH). In one of these trials, saw palmetto 160 mg twice daily for one year was ineffective for reducing moderate to severe symptoms of BPH when compared with placebo (14274). In the other trial, taking saw palmetto 320-960 mg daily for 72 weeks did not significantly improve symptoms when compared with placebo (17684). Additionally, meta-analyses of these trials and many of the small trials described below show that taking saw palmetto does not improve BPH-related signs and symptoms or International Prostate Symptom Scores (IPSS) (89441,102835,112804). While several small, low-quality clinical trials and observational studies in patients with BPH suggest that saw palmetto provides some improvement in urinary symptoms, nocturia, urinary flow, and/or residual urine volume when compared with placebo or baseline (6750,6764,6772,73315,73383,73385,73387,89441,96570,110541), other studies show that saw palmetto has no clinically meaningful effect on BPH-related signs and symptoms, including prostate volume (5093,6752,11314,73343,96409). The validity of several of these studies is limited due to the use of per-protocol analyses and/or a lack of placebo control groups. Beyond this, reasons for these discrepant findings are unclear; however, the mixed results may be due to use of different saw palmetto products, varying study methodologies, different patient populations, and varying symptom scoring tools. Additionally, research shows significant variation in the chemical composition of commercially available saw palmetto extracts (17305,89441). Several clinical trials have compared saw palmetto to 5-alpha reductase inhibitors such as finasteride (Proscar) or dutasteride (Avodart). Some small studies suggest that it may be comparable to these medications for relieving BPH symptoms, but with less effect on prostate size or prostate-specific antigen (PSA) levels (6424,96570). It may also be better tolerated, with a positive effect on sexual dysfunction (6424,6763,18215,89441). Additionally, one observational study in patients with BPH has found that taking saw palmetto 320 mg with tamsulosin 0.4 mg daily for 6 months is associated with similar improvements in IPSS and quality of life scores, but also has a lower risk of reduced libido, when compared with tamsulosin plus dutasteride 5 mg or finasteride 0.5 mg daily (110542). Some research has also compared saw palmetto to alpha-adrenergic blockers. Alpha-adrenergic blockers appear to have a faster onset of symptom relief (2732,6750), and saw palmetto might be less effective than the alpha-adrenergic blocker prazosin (Minipress). Although some studies and a meta-analysis suggest it is similarly effective to tamsulosin (Flomax) after 6-12 months of treatment for improving various symptoms of BPH (6775,6776,11243,89441,96570,104804,107483), another meta-analysis found that alpha-blockers were more effective than saw palmetto for these outcomes (102835). Additionally, tamsulosin appears to be more effective than saw palmetto for reducing prostate volume (104802). However, some research suggests that saw palmetto may be better tolerated than tamsulosin (107483). It is unclear if taking saw palmetto with tamsulosin can improve BPH symptoms. Several low-quality studies and a meta-analysis of two of these studies show no additional benefit over using tamsulosin alone (8901,89443,89448,96410). However, one study suggests that a specific saw palmetto extract (Permixon, Pierre Fabre Medicament) 320 mg daily is associated with a 29% decrease in the IPSS when taken alone, compared with a 37% decrease when taken along with tamsulosin 0.4 mg daily for 6 months. Tamsulosin alone was associated with a 31% decrease (104802). Saw palmetto has also been evaluated in combination with other ingredients. A meta-analysis of 8 clinical studies in adults with lower urinary tract symptoms due to BPH shows that taking saw palmetto in combination with other herbal ingredients does not improve urologic symptoms of BPH when compared with placebo or no intervention (112804). However, small, low-quality studies of various combinations of saw palmetto with other ingredients have demonstrated some benefit for improving symptoms of BPH, and some have shown equivalence to finasteride, tamsulosin, or tadalafil (Cialis). These ingredients include stinging nettle root (PRO 160/120, Dr. Willmar Schwabe Pharmaceuticals) (6763,17307,73330,89441); cernitin, beta-sitosterol, and vitamin E (11241); selenium and lycopene (Profluss, Konpharma) (90354,97255); pygeum, lycopene, Epilobium parviflorum, and pumpkin seed oil (ProstateEZE Max, Caruso's Natural Health) (92164); and quercetin and beta-sitosterol (Difaprost, Difass International) (96784). Additionally, one study suggests that an enriched form of saw palmetto oil containing 3% beta-sitosterol seems to be more effective than standard saw palmetto oil containing 0.3% beta-sitosterol in reducing IPSS scores (104803).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Androgenic alopecia. It is unclear if oral or topical saw palmetto is beneficial in patients with androgenic alopecia. Details: A small clinical study in males and females with androgenic alopecia shows that taking a specific saw palmetto oil (VISPO, Vidya Herbs) 100 mg daily for 16 weeks reduces hair fall and increases hair density but does not improve hair thickness, anagen-telogen ratio, or most subjective measures of hair growth when compared with placebo (112805). Other clinical research shows that taking saw palmetto extract 320 mg daily for 24 months is less effective for improving hair growth in males with androgenic alopecia when compared with finasteride 1 mg daily (89444). Topical saw palmetto has also been investigated for treating androgenic alopecia. Some clinical research shows that saw palmetto lotion, applied twice daily for 50 weeks, improves hair density by 27% in individuals with androgenic alopecia. However, a 13% improvement was observed in the placebo group, and no between-group comparisons were made (73435). Another small clinical study in male and females with mild to moderate androgenic alopecia shows that applying 5 mL of a lotion containing saw palmetto oil 20% (VISPO, Vidya Herbs) to the scalp for 30 minutes daily for 16 weeks reduces hair fall and increases hair density but does not improve hair thickness, anagen-telogen ratio, or subjective measures of hair growth when compared with placebo (112805). Saw palmetto has also been evaluated in combination with other ingredients. A very small clinical study in males with androgenic alopecia shows that taking a combination of saw palmetto extract 200 mg plus beta-sitosterol 50 mg twice daily for 18-24 months improves subjective scores of hair quantity and quality when compared with placebo (15550). Another small clinical study in males with androgenic alopecia receiving platelet-rich plasma every 3 weeks shows that applying 1 mL of topical saw palmetto, redensyl, and biotin daily for 12 weeks modestly improves subjective hair loss scores and photographic assessment of hair growth when compared with 1 mL of topical Procapil daily (112176). However, it is unclear if these effects are due to saw palmetto, other ingredients, or the combination.
• Asthma. Although there has been interest in using oral saw palmetto for asthma, there is insufficient reliable information about the clinical effects of saw palmetto for this purpose.
• Chronic bronchitis. Although there has been interest in using oral saw palmetto for chronic bronchitis, there is insufficient reliable information about the clinical effects of saw palmetto for this purpose.
• Chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS). It is unclear if oral saw palmetto is beneficial in patients with CP/CPPS. Details: Preliminary clinical research shows that oral saw palmetto 325 mg daily for one year does not significantly improve symptoms of CP/CPPS when compared with finasteride 5 mg once daily (11354). However, a clinical trial in patients with moderate to severe CP/CPPS shows that taking saw palmetto 160 mg orally twice daily for 12 weeks improves NIH Chronic Prostatitis Index (NIH-CPSI) score after two weeks of treatment in patients with moderate disease and after 4 weeks of treatment in patients with severe disease when compared with placebo. Independent of severity, 73% of patients taking saw palmetto report a 6-point reduction in NIH-CPSI total score, compared to 33% of patients taking placebo (107482). Saw palmetto extract has also been evaluated in combination with other ingredients. A preliminary clinical study shows that taking a combination of saw palmetto extract 320 mg, selenium 50 mcg, and lycopene oil extract 5 mg daily for 8 weeks improves symptoms and peak flow in patients with CP/CPPS when compared with baseline. However, these effects were not observed or were less significant in patients treated with saw palmetto alone (60442).
• Common cold. Although there has been interest in using oral saw palmetto for the common cold, there is insufficient reliable information about the clinical effects of saw palmetto for this purpose.
• Hirsutism. Although there has been interest in using oral and topical saw palmetto for hirsutism, there is insufficient reliable information about the clinical effects of saw palmetto for this purpose.
• Non-neurogenic lower urinary tract symptoms (LUTS). It is unclear if oral saw palmetto is beneficial in females with non-neurogenic LUTS. Details: A small clinical study in elderly Japanese females with LUTS shows that taking saw palmetto extract 320 mg daily for 12 weeks reduces daytime urinary frequency and might improve nocturia, but it does not seem to reduce urinary urgency, incontinence, straining, bladder pain, or urethral pain when compared with placebo (110540).
• Prostate cancer. Small preliminary studies suggest that saw palmetto does not reduce prostate cancer risk or symptoms associated with prostate cancer. Details: Population research shows that people who take saw palmetto supplements do not have a lower risk of developing prostate cancer (15217). Preliminary clinical research also shows that taking saw palmetto 960 mg daily before, during, and after radiation treatment for early prostate cancer does not significantly improve lower urinary tract symptoms when compared with placebo (96412).
• Prostatitis. Adding saw palmetto to antibiotic therapy seems to relieve some symptoms of bacterial prostatitis more effectively than antibiotics alone. Details: Preliminary clinical research in patients with bacterial prostatitis shows that taking saw palmetto extract daily for eight weeks, with prulifloxacin 600 mg daily for 15 days, reduces pain and urinary symptoms more than prulifloxacin alone, but the combination does not appear to improve bacterial eradication or sexual dysfunction more than the antibiotic alone (89442). One small clinical study in patients with chronic nonbacterial prostatitis shows that a specific saw palmetto extract (Prostamol Uno, Profluss) 320 mg daily improves symptoms when compared with no treatment (73329). Combinations of saw palmetto with other supplements have also been used with fluoroquinolone antibiotics, typically resulting in symptom improvement when compared with the antibiotic alone. These supplement combinations include saw palmetto, indole-3-carbinol, and epigallocatexin-3-gallate (Indigal Plus) 2 capsules twice daily for 3 months (73355); saw palmetto 160 mg, stinging nettle 120 mg, curcumin 200 mg, and quercetin 100mg (ProstaMEV plus FlogMEV) for 2 weeks (73346); and saw palmetto 320 mg, Bacillus coagulans 200 mg, and arbutin 100 mg (Lactorepens) daily for 30 days (96411).
• Sexual desire. Although there has been interest in using oral saw palmetto for sexual desire, there is insufficient reliable information about the clinical effects of saw palmetto for this purpose.
• Sexual dysfunction. Although there has been interest in using oral saw palmetto for sexual dysfunction, there is insufficient reliable information about the clinical effects of saw palmetto for this purpose. More evidence is needed to rate saw palmetto for these uses.

(Read more about SAW PALMETTO)

POSSIBLY EFFECTIVE

• Diabetes. Oral stinging nettle seems to improve glycemic control in patients with diabetes. Details: A meta-analysis of 8 small heterogeneous clinical trials in adults with type 2 diabetes shows that taking stinging nettle 1.5-10 grams in divided doses daily for 8-12 weeks reduces fasting blood glucose (FBG) by 18 mg/dL when compared with placebo (102865). Glycated hemoglobin (HbA1c) was not improved, but the study durations were not adequate to detect an improvement in this measure. Despite positive results on FBG, taking stinging nettle does not seem to improve insulin secretion or measures of insulin sensitivity (91519,102865,108903). Another meta-analysis of 3 small clinical studies in adults with type 2 diabetes shows that taking stinging nettle reduces HbA1c by about 1.3% when compared with placebo. This analysis also suggests stinging nettle reduces post-prandial blood glucose by about 114 mg/dL; however, this is based on a single study. Stinging nettle did not improve fasting blood glucose or insulin resistance in this analysis (111503). The validity of these findings is limited by the low quality and heterogeneity of included studies, as well as unclear dosing. Furthermore, since most research has been conducted in Iran, it is unknown if these findings are generalizable to other geographic locations. Stinging nettle has also been used in combination with other natural medicines. One small clinical study in adults with type 2 diabetes shows that taking a product containing stinging nettle leaf extract 200 mg, milk thistle 200 mg, and Boswellia serrata gum 200 mg three times daily for 3 months reduces FBP by about 28 mg/dL and HbA1c by about 1.5%, compared with a smaller reduction in the placebo group (96742). It is unclear if this effect is due to stinging nettle, the other ingredients, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). It is unclear if oral stinging nettle is beneficial for hay fever. Details: Taking stinging nettle leaf extract 300 mg 3-7 times daily at the first sign of hay fever symptoms seems to provide subjective improvement (7035). However, adding stinging nettle to conventional allergy medication might not provide any additional benefit. One small clinical study shows that adding stinging nettle tablets (Urtidin, Barij Essence Pharmaceutical Co.) 150 mg four times daily for 1 month to treatment with loratadine and nasal saline rinses does not improve symptoms of allergic rhinitis when compared with placebo with loratadine and nasal saline rinses (96743).
• Anemia. Although there is interest in using oral stinging nettle for anemia, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Asthma. Although there is interest in using oral stinging nettle for asthma, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Benign prostatic hyperplasia (BPH). It is unclear if oral stinging nettle is beneficial for BPH. Details: A meta-analysis of clinical research, including 5 clinical studies and 1,128 patients with BPH, shows that taking stinging nettle root extract 360-600 mg in divided doses daily for 2-12 months improves peak urinary flow rate and symptom scores while modestly reducing prostate volume when compared with control. However, the validity of these results is limited by significant heterogeneity due to the variability in the products used and the specific endpoints investigated (96744). In the largest clinical trial in the analysis, patients took stinging nettle root extract 120 mg three times daily for 6 months (76406). Stinging nettle has also been evaluated in combination products. Clinical research in patients with BPH shows that taking a specific combination product (PRO 160/120, Dr. Willmar Schwabe Pharmaceuticals) containing a specific extract of stinging nettle root (WS 1031) 120 mg plus a specific extract of saw palmetto fruit (WS 1473) 160 mg twice daily for 24-48 weeks seems to improve urinary tract symptoms when compared with control; the effect may last at least 48 weeks after treatment (15195,15551,76409). However, taking a different combination product does not seem to be beneficial. A small clinical study in patients with BPH shows that taking a product containing stinging nettle root extract 240 mg, saw palmetto, pumpkin seed oil, lemon bioflavonoid, and beta-carotene, three times daily for 6 months, does not improve symptoms of BPH (5093).
• Bleeding. Topical stinging nettle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some preliminary clinical research shows that applying 4 mL of a specific product (Ankaferd blood stopper, Mefar Ilaç Sanayi A.S) containing alpinia, licorice, thyme, stinging nettle, and common grape vine to the affected area reduces bleeding, but does not improve the time for episiotomy repair, when compared with using saline (31010).
• Gingivitis. Stinging nettle in a mouthwash solution has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with moderate gingival inflammation suggests that using 10 mL of mouthwash solution containing a 1:1:1 mixture of stinging nettle, juniper, and yarrow twice daily for 3 months does not reduce plaque or bleeding when compared with control (76443). It is not clear if this effect is due to stinging nettle, the other ingredients, or the combination.
• Gout. Although there is interest in using oral stinging nettle for gout, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Gulf war syndrome. It is unclear if oral stinging nettle is beneficial for Gulf war syndrome. Details: A very small exploratory clinical trial in males with Gulf war syndrome shows that taking stinging nettle leaf (Nature's Way) 1305 mg in two divided doses daily for 30 days modestly improves symptom severity when compared with placebo (108311). The clinical relevance of this finding is limited by the use of an unvalidated scoring scale. Additionally, it appears that most patients had mild, unspecified symptoms at baseline; it is unclear if stinging nettle is beneficial for moderate to severe symptoms.
• Hyperandrogenism. It is unclear if oral stinging nettle is beneficial in patients with hyperandrogenism. Details: Preliminary clinical research in females with hyperandrogenism shows that taking dried extract of stinging nettle root 300-600 mg daily for approximately 4 months decreases total and free testosterone levels, but not menstrual cycle conditions, oily skin, or acne, when compared with taking spironolactone and cyproterone (91520).
• Insect bite. Oral stinging nettle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that applying a homeopathic after-bite gel, containing stinging nettle, Echinacea, and marsh Labrador tea, on affected areas does not reduce erythema or itching after a mosquito bite when compared with placebo (89235).
• Kidney stones (nephrolithiasis). Although there is interest in using oral stinging nettle for kidney stones, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Myalgia. Although there is interest in using topical stinging nettle for myalgia, there is insufficient reliable information about the clinical effects of stinging nettle for this purpose.
• Osteoarthritis. Small clinical studies suggest that topical stinging nettle may modestly improve pain in patients with osteoarthritis. It is unclear if oral stinging nettle is beneficial. Details: Topically, stinging nettle leaf may have a counterirritant effect which may improve osteoarthritis pain in some patients. A small clinical study in patients ages 45-82 with osteoarthritis of the thumb shows that applying raw stinging nettle leaf to the thumb for 30 seconds daily for 1 week reduces pain and disability when compared with white dead nettle leaf control (12490). However, in another small clinical study in patients with knee osteoarthritis, topical application of raw stinging nettle leaf to the knee for 1 minute daily for 7 days does not seem to be more effective for reducing pain than applying a leaf from a related stingless nettle (76412). Non-raw stinging nettle has also been tried. In a small open-label study, a formulation of stinging nettle extract (Liquid PhytoCaps Nettle Leaf, Gaia Herbs) 13.33% compounded with lipobase oil-in-water emulsion and applied to the affected area twice daily for 2 weeks, modestly improves pain and function in patients with radiologically confirmed osteoarthritis when compared with baseline (76414). The validity of this finding is limited by the lack of a comparator group. Stinging nettle has also been evaluated orally, in combination with other ingredients. A clinical study in adults with knee osteoarthritis shows that taking a specific combination solution (Rosaxan, medAgil Gesundheitsgesellschaft mbH) containing stinging nettle extract 160 mg, rose hip puree 20 grams, devil's claw 108 mg, and vitamin D 200 IU daily for 12 weeks improves symptoms by an additional 28% and pain scores by an additional 33% when compared with placebo (96741). It is unclear if this effect is due to stinging nettle, the other ingredients, or the combination.
• Tinnitus. Oral stinging nettle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with tinnitus shows that taking a specific product containing stinging nettle, tansy, and rose hip (Neurotec, Rose Pharmed), 100 mg orally daily for 3 months does not improve auditory thresholds when compared with placebo. However, the product improved some subjective symptoms scores, such as perceived loudness and severity scores (110512).
• Urinary tract infections (UTIs). Although there is interest in using oral stinging nettle for UTIs, there is insufficient reliable information about the clinical effects of stinging nettle for this condition. More evidence is needed to rate stinging nettle for these uses.

(Read more about STINGING NETTLE)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Antidepressant-induced sexual dysfunction. It is unclear if oral yohimbine, a constituent of yohimbe, is beneficial for patients with antidepressant-induced sexual dysfunction. Details: Small clinical trials suggest that taking yohimbine, a constituent of yohimbe, improves sexual dysfunction associated with selective serotonin reuptake inhibitors (SSRIs) (3305,3306,3307,3311,3313,3970,3971,3972,3973). It is unclear if yohimbe bark is beneficial.
• Anxiety. There is limited evidence on the oral use of yohimbine, a constituent of yohimbe, for the management of various phobias. Details: A small clinical study in healthy adults with a fear of flying shows that taking yohimbine hydrochloride 10 mg as an adjunct to virtual reality exposure therapy (VRET) does not improve anxiety measures when compared with VRET alone (86819). However, another small clinical study in healthy adults with claustrophobia shows that taking yohimbine hydrochloride 10.8 mg prior to exposure-based treatment reduces peak fear after one week when compared with exposure-based treatment alone (86794). The effect of yohimbe bark has not been investigated in clinical research.
• Athletic performance. It is unclear if oral yohimbine, a constituent of yohimbe, is beneficial for athletic performance. Details: A small clinical study in professional soccer players shows that taking yohimbine, a constituent of yohimbe, 20 mg daily for 3 weeks does not improve exercise performance or build muscle mass when compared with placebo (86785). However, a small crossover study in physically active females undergoing an anaerobic exercise test shows that taking a single dose of oral yohimbine 2.5 mg 20 minutes prior to repeated sprints increases average power output, total work, and heart rate and decreases average fatigue index when compared with placebo. Additionally, taking yohimbine decreases lactic acid levels and increases epinephrine levels when compared with baseline or placebo (107849). Due to the single-dose nature of this study, the effects of continued administration of yohimbine on athletic performance are unclear. The effects of yohimbe bark have not been investigated in clinical research.
• Depression. It is unclear if oral yohimbine, a constituent of yohimbe, is beneficial in patients with depression. Details: A very small clinical study in patients with treatment-resistant major depressive disorder shows that taking yohimbine, a constituent of yohimbe, 30 mg daily for 10 days along with desipramine does not improve symptoms of depression when compared with desipramine alone (86834). Also, a small crossover trial in patients with major depressive disorder and/or a history of adverse childhood experiences shows that taking yohimbine 10 mg once does not alter approach-avoidance behaviors normally associated with depression when compared with placebo (111402). The effects of yohimbe bark have not been investigated in clinical research.
• Dry mouth. It is unclear if oral yohimbine, a constituent of yohimbe, is beneficial for dry mouth. Details: A very small clinical study shows that taking yohimbine, a constituent of yohimbe bark, 18 mg daily for 5 days improves symptoms of dry mouth in individuals treated with antidepressants when compared with placebo (86886). The effect of yohimbe bark has not been investigated in clinical research.
• Erectile dysfunction (ED). It is unclear if oral yohimbine, a constituent of yohimbe, is beneficial for ED. Details: The effects of yohimbe bark have not been investigated in clinical research. Most small clinical studies suggest that taking yohimbine, a constituent in yohimbe bark, seems to improve symptoms in adults with various types of ED, including organic, psychogenic, mixed, and others (3305,3307,3309,3311,3312,3313,10629,86827,86831,86878)(86882,86888,86896). A meta-analysis in patients with ED shows that taking 5-100 mg of oral yohimbine for 2-10 weeks increases the probability of erectile function improvement when compared with placebo. Also, the use of yohimbine in combination with either L-arginine or trazodone, but not as monotherapy, improves sexual function when compared with placebo (107848). These findings are limited by the high heterogeneity of the included studies. Due to insufficient data, guidelines from the American Urological Association do not recommend yohimbine as a treatment option for ED (86881).
• Fatigue. Although there is interest in using oral yohimbe for fatigue, there is insufficient reliable information about the clinical effects of yohimbe for this purpose.
• Obesity. Although there is interest in using oral yohimbe for obesity, there is insufficient reliable information about the clinical effects of yohimbe for this condition.
• Orthostatic hypotension. It is unclear if oral yohimbine, a constituent of yohimbe, is beneficial in patients with orthostatic hypotension. Details: Some preliminary clinical research shows that taking a single dose of yohimbine 5.4 mg increases systolic blood pressure and standing diastolic blood pressure in patients with orthostatic hypotension when compared with placebo or pyridostigmine (86811,86890). However, other preliminary clinical research shows that taking yohimbine does not improve blood pressure in patients with orthostatic hypotension due to autonomic failure when compared with placebo (86821). The effect of yohimbe bark has not been investigated in clinical research. More evidence is needed to rate yohimbe for these uses.

(Read more about YOHIMBE)

LIKELY SAFE ...when used in amounts commonly found in foods. Cola nut extract has Generally Recognized As Safe (GRAS) status in the US (4912).

POSSIBLY SAFE ...when used orally and appropriately, short-term. Cola nut has been used with apparent safety for up to 12 weeks (12811).

POSSIBLY UNSAFE ...when used orally, long-term, or in large amounts. Chewing cola nut is associated with an increased risk of mouth cancer and gastrointestinal cancer (11963). Cola nut also contains caffeine. Chronic use of caffeine, especially in large amounts, can sometimes produce tolerance, habituation, and psychological dependence (3719). Acute use of high doses, typically above 400 mg daily, has been associated with significant adverse effects such as tachyarrhythmia and sleep disturbances (11832). Abrupt discontinuance of caffeine can cause physical withdrawal symptoms (11733). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as cola nut, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

PREGNANCY: POSSIBLY SAFE
when used orally in amounts found in foods. Due to the caffeine content of cola nut, pregnant patients should closely monitor their intake to ensure moderate consumption. Fetal blood concentrations of caffeine approximate maternal concentrations (4260). The use of caffeine during pregnancy is controversial; however, moderate consumption has not been associated with clinically important adverse fetal effects (2708,2709,2710,2711,9606,11733,16014,16015). In some studies, consuming amounts over 200 mg daily is associated with a significantly increased risk of miscarriage (16014). This increased risk may be most likely to occur in those with genotypes that confer a slow rate of caffeine metabolism (98806). According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, most healthy pregnant patients can safely consume caffeine in doses up to 300 mg daily without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations (11733,98806). Advise keeping caffeine consumption below 300 mg daily. This is similar to the amount of caffeine in about 3 cups of coffee or tea. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as cola nut, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

PREGNANCY: POSSIBLY UNSAFE
when caffeine, a constituent of cola nut, is used orally in amounts over 300 mg daily. Caffeine crosses the placenta, producing fetal blood concentrations similar to maternal levels (4260). Advise keeping caffeine consumption from all sources below 300 mg daily (2708). High doses of caffeine throughout pregnancy have resulted in symptoms of caffeine withdrawal in newborn infants (9891). High doses of caffeine have also been associated with spontaneous abortion, premature delivery, and low birth weight (2709,2711,91033,91048,95949). Keep in mind that only the amount of added caffeine must be stated on product labels. The amount of caffeine found in ingredients such as cola nut, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product. In a study that included 2 large cohorts of mother/infant pairs, the first cohort with a median maternal plasma caffeine level of 168.5 ng/mL (range 29.5-650.5 ng/mL) during pregnancy, suggests birth weights and lengths were lower in the 4th quartile of caffeine intake compared with the 1st. By age 7, heights and weights were lower by 1.5 cm and 1.1 kg, respectively. In the second cohort of mother/infant pairs with higher maternal pregnancy plasma caffeine levels, median 625.5 ng/mL (range 86.2 to 1994.7 ng/mL), heights at age 8 were 2.2 cm lower, but there was no difference in weights (109846).

LACTATION: POSSIBLY SAFE
when used orally in amounts found in foods. Due to the caffeine content of cola nut, caffeine intake should be closely monitored while nursing. Breast milk concentrations of caffeine are thought to be approximately 50% of maternal serum concentrations. Minimal consumption would likely result in limited exposure to a nursing infant (9892).

LACTATION: POSSIBLY UNSAFE
when used orally in large amounts. Consumption of cola nut might cause sleep disturbances, irritability, and increased bowel activity in nursing infants due to its caffeine content (6026). Large doses or excessive intake of cola nut should be avoided during lactation. It is unknown whether potentially carcinogenic constituents of cola nut are transferred via breast milk.

(Read more about COLA NUT)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Damiana has Generally Recognized As Safe status (GRAS) for use in foods in the US (4912).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts (12,46933,11866).

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

(Read more about DAMIANA)

LIKELY SAFE ...when used orally in amounts commonly found in foods.

POSSIBLY SAFE ...when used orally in medicinal amounts, short-term. GABA has been used with apparent safety in doses of 75 mg to 1.5 grams daily for up to one month in small clinical studies (19361,19363,19369,110134,110135). There is insufficient reliable information available about the safety of GABA when used orally for longer than one month or when used sublingually or intravenously.

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

(Read more about GAMMA-AMINOBUTYRIC ACID (GABA))

POSSIBLY SAFE ...when horny goat weed extract is used orally and appropriately, short-term. A specific extract of horny goat weed containing 60 mg icariin, 15 mg daidzein, and 3 mg genistein (Xianling Gubao; Tong Ji Tang Pharmacal Company) has been used daily with apparent safety for up to 24 months (14900,97268). Another aqueous extract of horny goat weed containing up to 25.36% icariin has been used in a dose of 300 mL daily with apparent safety for up to 6 months (55452). Another horny goat weed extract has been used with apparent safety at doses up to 1000 mg daily (providing 200 mg icariin) for up to 30 days (108311).

POSSIBLY UNSAFE ...when used orally long-term or in high doses. Long-term use, or taking high doses of some species of horny goat weed, has been linked to serious adverse effects including respiratory arrest (10346).

PREGNANCY: POSSIBLY UNSAFE
when used orally. Horny goat weed might have androgenic activity (10346). Theoretically, it might harm a developing fetus; avoid using.

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about HORNY GOAT WEED)

POSSIBLY SAFE ...when used orally and appropriately. L-arginine has been used safely in clinical studies at doses of up to 24 grams daily for up to 18 months (3331,3460,3595,3596,5531,5532,5533,6028,7815,7816)(8014,8473,13709,31943,91195,91196,91963,99264,99267,110380)(110387). A tolerable upper intake level (UL) for arginine has not been established, but the observed safe level (OSL) of arginine intake established in clinical research is 20 grams (31996). ...when used intravenously and appropriately. Parenteral L-arginine is an FDA-approved prescription product (15). ...when used topically and appropriately. L-arginine appears to be safe when 5 grams is applied as a topical cream twice daily for 2 weeks or when a dentifrice is used at a dose of 1.5% w/w for up to 2 years (14913,96806). ...when inhaled, short-term. L-arginine appears to be safe when inhaled twice daily at a dose of 500 mg for up to 2 weeks (96807).

CHILDREN: POSSIBLY SAFE
when used orally in premature infants and children (8474,32286,96803,97392,110391). ...when used intravenously and appropriately (97392). Parenteral L-arginine is an FDA-approved prescription product (15). ...when used topically, short-term. A dentifrice containing L-arginine appears to be safe when used at a dose of 1.5% w/w for up to 2 years in children at least 3.7 years of age (96806). ...when inhaled, short-term. L-arginine appears to be safe when inhaled twice daily at a dose of 500 mg for up to 2 weeks in children at least 13 years of age (96807).

CHILDREN: POSSIBLY UNSAFE
when used intravenously in high doses. Parenteral L-arginine is an FDA-approved prescription product (15). However, when higher than recommended doses are used, injection site reactions, hypersensitivity reactions, hematuria, and death have occurred in children (16817).

PREGNANCY: POSSIBLY SAFE
when used orally and appropriately, short-term. L-arginine 12 grams daily for 2 days has been used with apparent safety in pregnancy during the third trimester (11828). L-arginine 3 grams daily has been taken safely during the second and/or third trimesters (31938,110379,110382). ...when used intravenously and appropriately, short-term. Intravenous L-arginine 20-30 grams daily has been used safely in pregnancy for up to 5 days (31847,31933,31961,31978).

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about L-ARGININE)

LIKELY SAFE ...when maca is consumed in food amounts (9926).

POSSIBLY SAFE ...when used orally and appropriately, short term. Maca appears to be safe in doses up to 3 grams daily for 4 months (9928,10218,18289,90278,108603).

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

(Read more about MACA)

POSSIBLY SAFE ...when used orally and appropriately, short-term. Taking muira puama 500-1050 mg daily, as part of a combination product, has been used with apparent safety for 1 month (63920,103224). There is insufficient reliable information available about the safety of muira puama when used long-term.

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

(Read more about MUIRA PUAMA)

LIKELY SAFE ...when used orally and appropriately in food amounts (4960,4969,5792,5797). Oat bran has Generally Recognized as Safe (GRAS) status in the US (4912). Whole grain oats 50-100 grams daily have been used for up to 1 year without serious adverse effects (97520).

POSSIBLY SAFE ...when used topically and appropriately (12). Lotion containing colloidal oat 1% has been used topically without adverse effects for up to 6 weeks (97518,103340). There is insufficient reliable information available about the safety of oats when used orally in medicinal amounts.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in food amounts (5792,5797).

(Read more about OATS)

LIKELY SAFE ...when used orally and appropriately. Saw palmetto has been safely used in clinical studies lasting up to 3 years (2735,6750,6752,6764,6772,6773,11354,14274,15550,17202,17306,17684,73315,73383,73384,73385,73389,89441,96410,96412,110540).

POSSIBLY SAFE ...when used rectally and appropriately. Saw palmetto has been used safely in clinical research at a dose of 640 mg once daily for 30 days (73387). However, the long-term safety of saw palmetto administered rectally is not known.

PREGNANCY AND LACTATION: LIKELY UNSAFE
when used orally. Saw palmetto has hormonal activity (6766); avoid using.

(Read more about SAW PALMETTO)

POSSIBLY SAFE ...when used orally and appropriately. Stinging nettle root 360-600 mg has been used safely for up to 1 year (5093,11230,15195,76406,96744). ...when used topically and appropriately (12490).

PREGNANCY: LIKELY UNSAFE
when used orally due to possible abortifacient and uterine-stimulant effects (4,6,19).

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about STINGING NETTLE)

POSSIBLY UNSAFE ...when used orally. Yohimbine, a constituent of yohimbe, has been associated with serious adverse effects including cardiac arrhythmia, agitation, myocardial infarction, seizure, and others (17465). Some research shows that yohimbine can be safely used under close medical supervision for up to 10 weeks (3305,3307,3311,3313). However, due to safety concerns, yohimbe should not be used without medical supervision.

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally. Yohimbe might have uterine relaxant effects and also cause fetal toxicity (19).

(Read more about YOHIMBE)

ADENOSINE (Adenocard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, cola nut might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.  Details Cola nut contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level. However, caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine (11771). It is recommended that methylxanthines and methylxanthine-containing products (including cola nut) be stopped 24 hours prior to pharmacological stress tests (11770). However, methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing (11771).

ALCOHOL (Ethanol) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, alcohol might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Concomitant use of alcohol and caffeine can increase caffeine serum concentrations and the risk of caffeine adverse effects. Alcohol reduces caffeine metabolism (6370).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, cola nut may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Cola nut contains caffeine. Caffeine is reported to have antiplatelet activity (8028,8029). This interaction has not been reported in humans.

ANTIDIABETES DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, taking cola nut with antidiabetes drugs might interfere with blood glucose control.  Details Cola nut contains caffeine. Some conflicting reports claim that caffeine might increase or decrease blood sugar (6024,8646).

BETA-ADRENERGIC AGONISTS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in cola nut might increase the clinical effects of beta-adrenergic agonists.  Details Cola nut contains caffeine. Theoretically, concomitant use of large amounts of caffeine might increase the cardiac inotropic effects of beta-agonists (15).

CARBAMAZEPINE (Tegretol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might reduce the effects of carbamazepine and increase the risk for convulsions.  Details Cola nut contains caffeine. Animal research suggests that taking caffeine can lower the anticonvulsant effects of carbamazepine and can induce seizures when taken in doses above 400 mg/kg (23559,23561). Human research has shown that taking caffeine 300 mg in three divided doses along with carbamazepine 200 mg reduces the bioavailability of carbamazepine by 32% and prolongs the plasma half-life of carbamazepine 2-fold in healthy individuals (23562).

CIMETIDINE (Tagamet) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, cimetidine might increase the effects and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Cimetidine decreases the rate of caffeine clearance by 31% to 42% (11736).

CLOZAPINE (Clozaril) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, cola nut might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.  Details Cola nut contains caffeine. Caffeine can increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg daily inhibit clozapine metabolism (5051). Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Researchers speculate that caffeine might inhibit CYP1A2. However, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to the interaction between clozapine and caffeine (13741).

CONTRACEPTIVE DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, contraceptive drugs might increase the effects and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Oral contraceptives can decrease the rate of caffeine clearance by 40% to 65% (2714,11737).

CYTOCHROME P450 1A2 (CYP1A2) INHIBITORS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, CYP1A2 inhibitors might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Caffeine is metabolized by CYP1A2 (3941,5051,11741,23557,23573,23580,24958,24959,24960,24962), (24964,24965,24967,24968,24969,24971,38081,48603).

DIPYRIDAMOLE (Persantine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, cola nut might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.  Details Cola nut contains caffeine. Caffeine may inhibit dipyridamole-induced vasodilation (11770,11772). It is recommended that methylxanthines and methylxanthine-containing products, such as cola nut, be stopped 24 hours prior to pharmacological stress tests (11770). Methylxanthines appear more likely to interfere with dipyridamole than with adenosine-induced stress testing (11771).

DISULFIRAM (Antabuse) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, disulfiram might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. In human research, disulfiram decreases the rate of caffeine clearance (11840).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, using cola nut with diuretic drugs might increase the risk of hypokalemia.  Details Cola nut contains caffeine. In excessive amounts, caffeine can reduce potassium levels due to stimulation of the sodium-potassium pump (23579,37905,37953,38003,38034). Certain diuretics can also lower potassium levels.

EPHEDRINE Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the risk for stimulant adverse effects.  Details Cola nut contains caffeine. There is evidence that using ephedrine with caffeine might increase the risk of serious life-threatening or debilitating adverse effects such as hypertension, myocardial infarction, stroke, seizures, and death (1275,6486,10307).

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, estrogens might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Estrogen inhibits caffeine metabolism (2714).

ETHOSUXIMIDE (Zarontin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might reduce the effects of ethosuximide and increase the risk for convulsions.  Details Cola nut contains caffeine. Animal research suggests that caffeine 92.4 mg/kg can decrease the anticonvulsant activity of ethosuximide (23560). However, this effect has not been reported in humans

FELBAMATE (Felbatol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might reduce the effects of felbamate and increase the risk for convulsions.  Details Cola nut contains caffeine. Animal research suggests that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate (23563). However, this effect has not been reported in humans.

FLUCONAZOLE (Diflucan) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, fluconazole might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Fluconazole decreases caffeine clearance by approximately 25% (11022).

FLUTAMIDE (Eulexin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might increase the levels and adverse effects of flutamide.  Details Cola nut contains caffeine. In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide (23553). This effect has not been reported in humans.

FLUVOXAMINE (Luvox) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, fluvoxamine might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Fluvoxamine reduces caffeine metabolism (6370).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, abrupt cola nut withdrawal might increase the levels and adverse effects of lithium.  Details Cola nut contains caffeine. Abrupt caffeine withdrawal can increase serum lithium levels. There are two case reports of lithium tremor that worsened upon abrupt coffee withdrawal (609,610).

METFORMIN (Glucophage) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, metformin might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Animal research suggests that metformin can reduce caffeine metabolism (23571).

METHOXSALEN (Oxsoralen) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, methoxsalen might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Methoxsalen can reduce caffeine metabolism (23572).

MEXILETINE (Mexitil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, mexiletine might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Mexiletine can decrease caffeine elimination by 50% (1260,11741).

MONOAMINE OXIDASE INHIBITORS (MAOIs) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the risk of a hypertensive crisis.  Details Cola nut contains caffeine. Caffeine has been shown to inhibit monoamine oxidase (MAO) A and B in laboratory studies (37724,37877,37912,38108). Concomitant intake of large amounts of caffeine with MAOIs might precipitate a hypertensive crisis (15). In a case report, a patient that consumed 10-12 cups of caffeinated coffee and took the MAOI tranylcypromine presented with severe hypertension (91086). Hypertension was resolved after the patient switched to drinking decaffeinated coffee.

NICOTINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use might increase the risk of hypertension.  Details Cola nut contains caffeine. Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly (36549).

PENTOBARBITAL (Nembutal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, cola nut might decrease the effects of pentobarbital.  Details Cola nut contains caffeine. Theoretically, caffeine might negate the hypnotic effects of pentobarbital (13742).

PHENOBARBITAL (Luminal) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might reduce the effects of phenobarbital and increase the risk for convulsions.  Details Cola nut contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital (23558,23559,23561). However, this effect has not been reported in humans.

PHENOTHIAZINES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, phenothiazines might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Phenothiazines can reduce the metabolism of caffeine by inhibiting cytochrome P450 1A2 (CYP1A2) (23573,23574).

PHENYLPROPANOLAMINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure (11738). Phenylpropanolamine also seems to increase caffeine serum levels (13743).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might reduce the effects of phenytoin and increase the risk for convulsions.  Details Cola nut contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenytoin (23559,23561). The effect does not seem to be related to the seizure threshold-lowering effects of caffeine. However, the exact mechanism of this interaction is unclear.

PIOGLITAZONE (Actos) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might increase the levels and clinical effects of pioglitazone.  Details Cola nut contains caffeine. Animal research suggests that caffeine can modestly increase the maximum concentration, area under the curve, and half-life of pioglitazone, and also reduce its clearance. This increased the antidiabetic effects of pioglitazone (108812). However, the exact mechanism of this interaction is unclear.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, quinolone antibiotics might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Quinolones (also called fluoroquinolones) can decrease caffeine clearance by inhibiting cytochrome P450 1A2 (CYP1A2) (606,607,608,23554,23555,23556).

RILUZOLE (Rilutek) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of both caffeine and riluzole.  Details Cola nut contains caffeine. Caffeine and riluzole are both metabolized by cytochrome P450 1A2, and concomitant use might reduce metabolism of one or both agents (11739).

STIMULANT DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Theoretically, concomitant use might increase stimulant adverse effects.  Details Cola nut contains caffeine. Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects (11832).

TERBINAFINE (Lamisil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, terbinafine might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. Terbinafine decreases the rate of intravenous caffeine clearance by 19% (11740).

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, cola nut might increase the levels and adverse effects of theophylline.  Details Cola nut contains caffeine. Large amounts of caffeine might inhibit theophylline metabolism (11741).

TIAGABINE (Gabitril) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might increase the levels and adverse effects of tiagabine.  Details Cola nut contains caffeine. Animal research suggests that chronic caffeine administration can increase the serum concentrations of tiagabine. However, concomitant use does not seem to reduce the antiepileptic effects of tiagabine (23561).

TICLOPIDINE (Ticlid) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, ticlopidine might increase the levels and adverse effects of the caffeine in cola nut.  Details Cola nut contains caffeine. In vitro evidence suggests that ticlopidine can inhibit caffeine metabolism (23557). However, this effect has not been reported in humans.

VALPROATE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cola nut might reduce the effects of valproate and increase the risk for convulsions.  Details Cola nut contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of valproate (23558,23559,23561,37882). However, this effect has not been reported in humans.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of both verapamil and caffeine.  Details Cola nut contains caffeine. Verapamil increases plasma caffeine concentrations by 25% (11741).

(Read more about COLA NUT)

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking damiana with antidiabetes drugs might increase the risk of hypoglycemia.  Details Animal research shows that taking damiana lowers blood glucose level (4,25016).

(Read more about DAMIANA)

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking GABA with antihypertensive drugs might increase the risk of hypotension.  Details Some clinical research shows that GABA can decrease blood pressure in patients with hypertension (19367).

CNS DEPRESSANTS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, GABA might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.  Details Endogenous GABA has well-established relaxant effects (51152) and GABA(A) receptors have an established physiological role in sleep (51143). However, the effects of GABA supplements are unclear, as it is unknown whether exogenous GABA crosses the blood-brain barrier (51120,51153,90570). Although there have been limited reports of drowsiness or tiredness with GABA supplements (5115,19364), these effects have not been widely reported in clinical studies. Additionally, intravenous GABA 0.1-1 mg/kg has been shown to induce anxiety in a dose-dependent manner (5116).

(Read more about GAMMA-AMINOBUTYRIC ACID (GABA))

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, horny goat weed might increase the risk of bleeding.  Details In vitro research and animal research shows that horny goat weed can inhibit platelet aggregation and thrombus formation (105832). This effect has not been reported in humans.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, horny goat weed might increase the risk of hypotension.  Details Laboratory research suggests that horny goat weed might have hypotensive effects (10346). This effect has not been reported in humans.

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, horny goat weed might increase the effects and side effects of CYP1A2 substrates.  Details In vitro, horny goat weed leaf extract inhibits CYP1A2 (97267). This effect has not been reported in humans.

CYTOCHROME P450 2B6 (CYP2B6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, horny goat weed might increase the effects and side effects of CYP2B6 substrates.  Details In vitro, horny goat weed leaf extract inhibits CYP2B6 (97267). This effect 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, horny goat weed might increase the effects and side effects of CYP3A4 substrates.  Details In vitro, horny goat weed extract inhibits CYP3A4 and suppresses CYP3A4 mRNA expression (112708). This effect has not been reported in humans.

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of horny goat weed with estrogens might increase their therapeutic and adverse effects.  Details In vitro evidence suggests that horny goat weed has estrogenic activity. In clinical research, horny goat weed has been shown to increase blood levels of estrogen in some females (16061,16063,16060,55452).

(Read more about HORNY GOAT WEED)

ACE INHIBITORS (ACEIs) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use of L-arginine and ACE inhibitors may increase the risk for hypotension and hyperkalemia.  Details Combining L-arginine with some antihypertensive drugs, especially ACE inhibitors, seems to have additive vasodilating and blood pressure-lowering effects (7822,20192,31854,31916). Furthermore, ACE inhibitors can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients (32213,32218). Theoretically, concomitant use of ACE inhibitors with L-arginine may increases the risk of hyperkalemia.

ANGIOTENSIN RECEPTOR BLOCKERS (ARBs) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use of L-arginine and ARBs may increase the risk of hypotension and hyperkalemia.  Details L-arginine increases nitric oxide, which causes vasodilation (7822). Combining L-arginine with ARBs seems to increase L-arginine-induced vasodilation (31854). Furthermore, ARBs can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients (32213,32218). Theoretically, concomitant use of ARBs with L-arginine may increases the risk of hyperkalemia.

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of L-arginine with anticoagulant and antiplatelet drugs might have additive effects and increase the risk of bleeding.  Details Preliminary research suggests that L-arginine infusions reduce platelet aggregation in humans (32260,31864,32239,32220,32257,32263,32276,32188). The clinical significance of this effect is unclear.

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of L-arginine might have additive effects with antidiabetes drugs.  Details Preliminary clinical research shows that L-arginine decreases blood glucose levels in patients with type 2 diabetes (31964,32085,31964,104225).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use of L-arginine and antihypertensive drugs may increase the risk of hypotension.  Details L-arginine increases nitric oxide, which causes vasodilation (7822). Clinical evidence shows that L-arginine can reduce blood pressure in some individuals with hypertension (7818,10636,31871,32201,32167,32225,31923,32232,110383,110384). Furthermore, combining L-arginine with some antihypertensive drugs seems to have additive vasodilating and blood pressure-lowering effects (7822,20192,31854,31916).

ISOPROTERENOL (Isuprel) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, concurrent use of isoproterenol and L-arginine might result in additive effects and hypotension.  Details Preliminary clinical evidence suggests that L-arginine enhances isoproterenol-induced vasodilation in patients with essential hypertension or a family history of essential hypertension (31932).

POTASSIUM-SPARING DIURETICS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically concomitant use of potassium-sparing diuretics with L-arginine may increases the risk of hyperkalemia.  Details Potassium-sparing diuretics can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients (32213,32218).

SILDENAFIL (Viagra) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concurrent use of sildenafil and L-arginine might increase the risk for hypotension.  Details In vivo, concurrent use of L-arginine and sildenafil has resulted in increased vasodilation (7822,8015,10636). Theoretically, concurrent use might have additive vasodilatory and hypotensive effects. However, in studies evaluating the combined use of L-arginine and sildenafil for erectile dysfunction, hypotension was not reported (105065).

TESTOSTERONE Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of L-arginine and testosterone might have additive effects.  Details In clinical research, L-arginine increases the level of testosterone in male patients with erectile dysfunction (102586,104222). The clinical significance of this finding is unclear.

(Read more about L-ARGININE)

(Read more about MACA)

(Read more about MUIRA PUAMA)

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, oats may have additive effects with antidiabetic agents and might increase the risk of hypoglycemia.  Details Consuming oats can decrease blood glucose in patients with diabetes (4980,4982,6266,103345). In those who require insulin, taking oats 100 grams daily for 2 days reduces the insulin dose required to achieve metabolic control (103336).

INSULIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Concomitant use of oats and insulin might increase the risk of hypoglycemia.  Details In patients with insulin-dependent type 2 diabetes, taking oats 100 grams daily for 2 days reduces the insulin dose required to achieve metabolic control (103336).

(Read more about OATS)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Saw palmetto might increase the risk of bleeding with anticoagulant or antiplatelet drugs.  Details Saw palmetto is reported to prolong bleeding time (8659). Theoretically, it might increase the risk of bleeding when used concomitantly with anticoagulant or antiplatelet drugs.

CONTRACEPTIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Saw palmetto might reduce the effectiveness of contraceptive drugs.  Details Saw palmetto might have antiestrogenic effects (6766). Theoretically, it might interfere with contraceptive drugs taken concomitantly.

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Saw palmetto might reduce the effectiveness of estrogens.  Details Saw palmetto might have antiestrogenic effects (6766). Theoretically, it might interfere with estrogens taken concomitantly.

(Read more about SAW PALMETTO)

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, stinging nettle might have additive effects with antidiabetes drugs.  Details Clinical research shows that stinging nettle might decrease blood glucose levels in patients with diabetes (91519,102865).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, combining stinging nettle with diuretic drugs may have additive effects.  Details Animal research suggests that the above ground parts and roots of stinging nettle may have a diuretic effect (1,4,11,76402).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, stinging nettle might reduce excretion and increase levels of lithium.  Details Animal research suggests that stinging nettle has diuretic and natriuretic properties, which could alter the excretion of lithium (76402). The dose of lithium might need to be decreased.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D There is some concern that stinging nettle might decrease the effects of anticoagulant drugs such as warfarin.  Details Stinging nettle contains a significant amount of vitamin K (19). When taken in large quantities, this might interfere with the activity of warfarin.

(Read more about STINGING NETTLE)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, combining yohimbe bark with antiplatelet or anticoagulant drugs might have additive effects; however, this has not been reported in clinical research.  Details Research in healthy adults shows that taking yohimbine, a constituent of yohimbe bark, in doses of 8 mg or more, seems to inhibit platelet aggregation in vitro by binding to the alpha-2 adrenoceptor (86773,86806,86835,86853). The effects of yohimbe bark itself are unclear; yohimbe bark contains 0.6% to 1.38% yohimbine, but it is unclear how much is absorbed (86862,89263).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, yohimbe might reduce the effects of antihypertensive drugs.  Details Yohimbine, a constituent of yohimbe, is an alpha-2 adrenoceptor antagonist and has been reported to increase blood pressure in clinical research. Theoretically, concomitant use of yohimbe and antihypertensive drugs can interfere with blood pressure control (11,17465).

CLONIDINE (Catapres) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, yohimbe might precipitate clonidine withdrawal.  Details Chronic clonidine use can downregulate alpha-2 adrenoreceptors. Animal research and one human case report suggest that concomitant administration of yohimbine, an alpha-2 adrenoceptor antagonist, may precipitate clonidine withdrawal and lead to sympathomimetic toxicity, including hypertensive crisis (111406).

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

CYTOCHROME P450 2D6 (CYP2D6) INHIBITORS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B CYP2D6 inhibitors may increase the levels and adverse effects of yohimbine, a constituent of yohimbe.  Details In vitro and clinical research shows that the yohimbe bark constituent, yohimbine, is metabolized by CYP2D6 isoenzymes (105688,105697,105698). Paroxetine, a cytochrome P450 (CYP) 2D6 inhibitor, increases the maximum serum concentration of yohimbine and reduces the clearance of yohimbine compared to yohimbine alone in patients who are extensive CYP2D6 metabolizers. (114932).

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, yohimbe might increase the levels and adverse effects of CYP2D6 substrates.  Details In vitro research suggests that yohimbine, a constituent of yohimbe bark, inhibits CYP2D6 enzyme activity (23117).

CYTOCHROME P450 3A4 (CYP3A4) INHIBITORS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of yohimbine, a constituent of yohimbe bark.  Details In vitro and clinical research shows that the yohimbe bark constituent, yohimbine, is metabolized by CYP3A4 enzymes (105688,105698). Theoretically, drugs that inhibit CYP3A4 might increase the levels and adverse effects of yohimbine.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, yohimbe might decrease the levels and clinical effects of CYP3A4 substrates.  Details In vitro research shows that yohimbe extract induces CYP3A4 enzymes (111404).

MONOAMINE OXIDASE INHIBITORS (MAOIs) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Likely •  Level of Evidence = D Concomitant use of MAOIs with yohimbe can result in additive effects.  Details Yohimbine, a constituent of yohimbe, has MAO inhibitory effects. At high doses, yohimbine is a non-selective inhibitor of MAO (11,12).

PAROXETINE (Paxil) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Paroxetine decreases the clearance of yohimbine and may increase its effects.  Details Paroxetine, a cytochrome P450 (CYP) 2D6 inhibitor, increases the maximum serum concentration of yohimbine by about 350% and reduces the clearance of yohimbine by about 80% compared to yohimbine alone in patients who are extensive CYP2D6 metabolizers. No significant changes in pharmacokinetic parameters of yohimbine were observed with coadministration of paroxetine in patients who are poor CYP2D6 metabolizers (114932).

PHENOTHIAZINES Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, using yohimbine with phenothiazines might have additive effects.  Details Yohimbine, a constituent of yohimbe, has alpha-2 adrenergic antagonist effects. Theoretically, combining it with phenothiazines can cause additive alpha-2 adrenergic antagonism (19).

STIMULANT DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking yohimbe with stimulant drugs can have additive effects.  Details Yohimbine, a constituent of yohimbe, has sympathomimetic effects and increases blood pressure in a dose-dependent manner. Theoretically, taking yohimbe with stimulant drugs can have additive stimulant and hypertensive effects (11,12,105698).

TRICYCLIC ANTIDEPRESSANTS (TCAs) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking yohimbe with TCAs can increase adverse effects.  Details A small clinical study in patients taking TCAs for at least 4 weeks shows that receiving doses of intravenous yohimbine 2.5-20 mg daily for up to 7 days precipitates severe anxiety, agitation, and tremor (105881). The effects of yohimbe bark itself are unclear; oral yohimbe bark contains 0.6% to 1.38% yohimbine, but it is unclear how much is absorbed (86862,89263).

(Read more about YOHIMBE)

General ...Orally, cola nut is well tolerated when eaten in the amounts found in food. It seems to be well tolerated when used medicinally and appropriately, short-term. However, the caffeine found in cola nut may cause adverse effects when taken in large amounts.
Most Common Adverse Effects:
Orally: Dyspepsia, skin discoloration.
Serious Adverse Effects (Rare):
Orally: Increased risk of oral cancer, gastrointestinal cancer, and West African crystalline retinopathy with long-term use.

Cardiovascular ...Orally, acute administration of caffeine can cause increased blood pressure. However, regular consumption of caffeine does not seem to increase either blood pressure or pulse, even in mildly hypertensive patients (1451,1452,2722). Epidemiological research suggests there is no association of caffeine consumption with incidence of hypertension (38190). Habitual coffee consumption also doesn't seem to be related to hypertension, but habitual consumption of sugared or diet cola is associated with development of hypertension (13739).
Epidemiological research has also found that regular caffeine intake of up to 400 mg daily is not associated with an increased incidence of atrial fibrillation (38018,38076,91028,91034,97451,97453), atherosclerosis (38033), cardiac ectopy (91127), stroke (37804), ventricular arrhythmia (95948,97453), or cardiovascular disease in general (37805,98806).

Dermatologic ...Orally, chewing cola nut has been reported to cause bright yellow skin pigmentation (57680).

Endocrine ...Some evidence shows that caffeine, which is found in cola nut, is associated with fibrocystic breast disease, breast cancer, and endometriosis; however, this is controversial since findings are conflicting (8043). Restricting caffeine in people with fibrocystic breast conditions doesn't seem to affect breast nodularity, swelling, or pain (8996). Also, a population analysis of the Women's Health Initiative observational study has found no association between consumption of caffeine-containing beverages and the incidence of invasive breast cancer in models adjusted for demographic, lifestyle, and reproductive factors (108806). Also, a dose-response analysis of two low-quality observational studies has found that high consumption of caffeine is not associated with an increased risk of breast cancer (108807).
Clinical research in healthy adults shows that increased consumption of caffeine results in increased insulin resistance (91023).

Gastrointestinal ...Orally, cola nut may induce gastric acid secretion and cause dyspepsia and peptic ulceration (57672,57674,57683). The caffeine found in cola nut may cause feeding intolerance and gastrointestinal irritation in infants (6023).

Genitourinary ...Orally, the caffeine in cola nut may increase voiding, give a sense of urgency, and irritate the bladder (37874,37961,104580). In males with lower urinary tract symptoms, caffeine intake increased the risk of interstitial cystitis/painful bladder syndrome (38115).

Immunologic ...Cola nut contains caffeine. Caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare (11315).

Musculoskeletal ...Cola nut contains caffeine. Epidemiological evidence regarding the relationship between caffeine use and the risk for osteoporosis is contradictory. Caffeine can increase urinary excretion of calcium (2669,10202,11317). Females identified with a genetic variant of the vitamin D receptor appear to be at an increased risk for the detrimental effect of caffeine on bone mass (2669). However, moderate caffeine intake of less than 400 mg daily does not seem to significantly increase osteoporosis risk in most postmenopausal adults with normal calcium intake (2669,6025,10202,11317,98806).

Neurologic/CNS ...Orally, cola nut may prolong sleep latencies and suppress REM and 3rd and 4th stages of sleep (57697). Cola nut has also been reported to cause insomnia in children (10755) and may exacerbate sleep disturbances in patients with acquired immunodeficiency syndrome (AIDS) (10204). Caffeine, a constituent of cola nut, can cause headaches, anxiety, jitteriness, restlessness, and nervousness (36466,37694,37755,37806,37865,37830,37889,38223,95952).

Ocular/Otic ...Orally, cola nut has been associated with an increased risk for West African crystalline retinopathy in one retrospective, observational case series (57667).
Cola nut contains caffeine. In individuals with glaucoma, caffeine intake has been found to increase intraocular pressure. This did not occur in patients without glaucoma (36462,36464,36465,37670). The magnitude of this effect seems to depend on individual tolerance to caffeine. Some research in healthy young adults shows that caffeine increases intraocular pressure to a greater degree in low-consumers of caffeine (i.e., 1 cup of coffee or less daily) when compared to high-consumers (i.e., those consuming 2 cups of coffee or more daily) (100371). The peak increase of intraocular pressure seems to occur at about 1.5 hours after caffeine ingestion, and there is no notable effect 4 hours after ingestion (36462,100371).

Oncologic ...Orally, chewing cola nut has been associated with an increased risk of oral and gastrointestinal cancer. Cola nut contains high amounts of tannins and N-nitroso compounds, which are carcinogenic. The risk may be even higher in smokers (11963).

Psychiatric ...Cola nut contains caffeine. Caffeine may lead to habituation and physical dependence with amounts as low as 100 mg daily (36353,36355). Higher doses of caffeine have caused nervousness, agitation, anxiety, irritability, delirium, depression, sleep disturbances, impaired attention, psychosis, and panic attacks (36505,37717,37818,37839,37857,37982,38004,38017,38028,38072). Abrupt discontinuation of caffeine may result in physical withdrawal symptoms, including headache, fatigue, drowsiness, decreased physical energy, difficulty concentrating, depression, anxiety, irritability, and reduced alertness (13738).

(Read more about COLA NUT)

General ...Orally, adverse effects to damiana seem to be rare; however, a thorough safety evaluation has not been conducted.

Neurologic/CNS ...Orally, 200 grams of damiana extract has caused tetanus-like convulsions and paroxysms resulting in symptoms similar to rabies or strychnine poisoning (4).

(Read more about DAMIANA)

General ...Orally, GABA seems to be generally well tolerated. Sublingually, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.
Most Common Adverse Effects:
Orally: Drowsiness, gastric upset, minor throat burning, muscle weakness, and nausea.

Cardiovascular ...Intravenously, GABA can cause dose-related increases in blood pressure and pulse (5116).

Gastrointestinal ...Orally, minor throat burning has been associated with GABA in one study (5115). In another study in which GABA was administered with phosphatidylserine, one patient experienced severe gastric distress, two patients reported moderate nausea, and one reported constipation (19364). Children with cerebral palsy taking GABA experienced nausea and decreased appetite (19362).

Genitourinary ...In one study, one patient treated with oral GABA and phosphatidylserine reported transient amenorrhea (19364).

Musculoskeletal ...Orally, minor adverse effects associated with GABA included muscle weakness (5115).

Neurologic/CNS ...Orally, GABA may cause drowsiness, headache, or tiredness (5115,19364,112830). Four children with cerebral palsy taking GABA had convulsions, and an unspecified number experienced motor restlessness. However, causality of these adverse effects was not clear, and the dose of GABA was not specified (19362). Intravenously, GABA 50 mg has been associated with a "lack of alertness" in healthy female volunteers (51159).

Psychiatric ...Intravenously, GABA 0. 1-1.0 mg/kg has been shown to induce anxiety, dysphoria, and mood disturbances in a dose-dependent manner (5116).

Other ...In one study, patients taking GABA experienced a slight warming of the body (19370).

(Read more about GAMMA-AMINOBUTYRIC ACID (GABA))

General ...Orally, horny goat weed seems to be well tolerated when used short-term.
Most Common Adverse Effects:
Orally: Dizziness, dry mouth, nosebleed, thirst, and vomiting.
Serious Adverse Effects (Rare):
Orally: Respiratory arrest.

Cardiovascular ...A 66-year-old male with a history of cardiovascular disease developed tachyarrhythmia after taking horny goat weed for 2 weeks (13006). It is not clear if this product contained only horny goat weed or a combination of ingredients; therefore, assigning causality is not possible.

Gastrointestinal ...Orally, long-term use of horny goat weed has been associated with reports of vomiting, dry mouth, thirst, and nosebleed (10346).

Hepatic ...A case of hepatotoxicity characterized by abdominal pain, nausea, vomiting, and fever has been reported in a 40-year-old male patient with hepatitis C, after a month of taking one tablet daily of a combination product containing horny goat weed and multiple other ingredients (Enzyte, Vianda). Symptoms improved following cessation of the product, but it is not clear if they were due to horny goat weed, another ingredients, or hepatitis C (91590). An observational study over 24 years found 26 cases of drug-induced hepatoxicity associated with horny goat weed (112707).

Musculoskeletal ...Orally, large doses of horny goat weed may cause exaggeration of tendon reflexes to the point of spasm (10346).

Neurologic/CNS ...Orally, long-term use of horny goat weed has been associated with reports of dizziness (10346).

Psychiatric ...There is a case report of hypomania in a 66-year-old male who took horny goat weed for 2 weeks (13006). It is not clear if this product contained only horny goat weed or a combination of ingredients; therefore, assigning causality is not possible.

Pulmonary/Respiratory ...Orally, large doses of horny goat weed may cause respiratory arrest (10346).

(Read more about HORNY GOAT WEED)

General ...Oral, intravenous, and topical L-arginine are generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, bloating, nausea, diarrhea, headache, insomnia, flushing.
Intravenously: Excessively rapid infusion can cause flushing, headache, nausea and vomiting, numbness, and venous irritation.

Cardiovascular ...L-arginine taken orally by pregnant patients in a nutrition bar containing other antioxidants was associated with a 36% greater risk of palpitations when compared with a placebo bar (91197). It is unclear if this effect was due to L-arginine, other ingredients, or other factors.

Dermatologic ...Orally, arginine can cause flushing, rash, and hives (3460,32138,102587,104223). The skin reactions were likely of allergic etiology as oral L-arginine has been associated with eosinophilia (32138). In one case report, intravenous administration caused allergic reactions including urticaria, periorbital edema, and pruritus (11830). Excessively rapid infusion of L-arginine has caused flushing, local venous irritation, numbness. Extravasation has caused necrosis and superficial phlebitis (3330,16817).

Gastrointestinal ...Orally, L-arginine has been reported to cause nausea, diarrhea, vomiting, dyspepsia, gastrointestinal discomfort, and bloating (1363,31855,31871,31972,31978,32261,90198,91197,96811,99243)(102587,102592).
Orally, L-arginine has been reported to cause esophagitis in at least six adolescents. Symptoms, which included pain and dysphagia, occurred within 1-3 months of treatment in most cases (102588). There are at least two cases of acute pancreatitis possibly associated with oral L-arginine. In one case, a 28-year-old male developed pancreatitis after consuming a shake containing 1.2 grams of L-arginine daily as arginine alpha-ketoglutarate. The shake also contained plant extracts, caffeine, vitamins, and other amino acids. Although there is a known relationship between L-arginine and pancreatitis in animal models, it is not clear if L-arginine was directly responsible for the occurrence of pancreatitis in this case (99266).
Intravenously, excessively rapid infusion of L-arginine has been reported to cause nausea and vomiting (3330,16817).

Musculoskeletal ...Intravenous L-arginine has been associated with lower back pain and leg restlessness (32273). Orally, L-arginine has been associated with asthenia (32138).

Neurologic/CNS ...Orally, L-arginine has been associated with headache (31855,31955,32261,91197,102587,102592), insomnia, fatigue (102587,102592), and vertigo (32150,102592).

Oncologic ...In breast cancer patients, L-arginine stimulated tumor protein synthesis, which suggests stimulated tumor growth (31917).

Pulmonary/Respiratory ...When inhaled, L-arginine can cause airway inflammation and exacerbation of airway inflammation in asthma (121). However, two studies assessing oral L-arginine in patients with asthma did not detect any adverse airway effects (31849,104223).

Renal ...Intravenously, L-arginine has been associated with natriuresis, kaliuresis, chloruresis, and systemic acidosis (32225). Orally, L-arginine can cause gout (3331,3595).

Other ...Orally, L-arginine has been associated with delayed menses, night sweats, and flushing (31855).

(Read more about L-ARGININE)

General ...Orally, no adverse effects have been reported with the medicinal use of maca. However, a thorough evaluation of safety outcomes has not been conducted.

Gastrointestinal ...Consumption of fresh, uncooked maca may cause stomach pain (40231).

(Read more about MACA)

General ...No adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.

(Read more about MUIRA PUAMA)

General ...Orally, oats are well tolerated.
Most Common Adverse Effects:
Orally: Abdominal distension, bloating, flatulence, and unpleasant taste.
Topically: Burning, contact dermatitis, itching, and redness.

Dermatologic ...Topically, oat-containing preparations can cause contact dermatitis (12515). Redness, burning, and itchiness have also been reported (103340).

Gastrointestinal ...When consumed orally, oats provide fiber. Increasing fiber in the diet can cause flatulence, bloating, abdominal distention, and unpleasant taste. To minimize side effects, doses should be slowly titrated to the desired level. These adverse effects usually subside with continued use (12514).
In patients who have difficulty chewing food, or those with conditions that decrease small bowel motility, oat bran may cause bezoars (concretions) and intestinal obstruction. Oats and oat bran are unlikely to cause obstruction without other causative factors (4979,4985).

Immunologic ...In a case report, a 45-year-old male developed acute generalized urticaria, facial angioedema, and dyspnea immediately after consuming oat flour. The reaction resolved after emergency care for anaphylaxis. Further investigation revealed an IgE-mediated hypersensitivity reaction to oat proteins (113490).

(Read more about OATS)

General ...Orally, saw palmetto is well tolerated and adverse effects are mild, infrequent, and reversible.
Most Common Adverse Effects:
Orally: Abdominal pain, constipation, decreased libido, diarrhea, dizziness, fatigue, headache, nausea, rhinitis, vomiting.

Cardiovascular ...Occasionally, cases of hypertension, postural hypotension, tachycardia, angina pectoris, arrhythmia, extrasystole, angiopathy, myocardial infarction, and congestive heart failure have been reported in patients using saw palmetto orally (6424,6484,6752,6772,17684,73388,89441). One case of severe bradycardia and second degree heart block was reported in a 64 year-old male taking an unknown amount of saw palmetto for a few weeks (96413).

Dermatologic ...A case report describes a 61-year-old male who developed a fixed drug eruption with localized blisters and erosions three days after starting oral saw palmetto. The lesions resolved when saw palmetto was stopped, but recurred when it was reintroduced six months later. Topical corticosteroid treatment was necessary and the patient was left with some residual hyperpigmented patches (104805). A combination of saw palmetto and beta-sitosterol has been associated with a single report of worsening acne (15550).

Endocrine ...Two case reports involving one 11-year-old female undergoing treatment for telogen effluvium and another 10-year-old female undergoing treatment for hirsutism, describe hot flashes and the onset of menarche associated with use of saw palmetto. One of these patients was consuming saw palmetto in a food supplement; the other was taking a supplement containing saw palmetto 320 mg daily (73361,96414). In both cases, the hot flashes resolved following treatment discontinuation. In one case, a rechallenge with saw palmetto caused a recurrence of hot flashes.

Gastrointestinal ...Gastrointestinal complaints such as nausea, vomiting, constipation, diarrhea, gastralgia, and halitosis are the most frequently reported adverse effects associated with saw palmetto (6484,6752,60442,73315,73320,73348,73354,73383,73385,73388,89441). Less often, cases of duodenal ulcer, dyspepsia, or heartburn have been reported (6772,73329,73354). Meteorism (intestinal gas accumulation) has also been reported with saw palmetto, although causality was unclear (60442).

Genitourinary ...Some clinicians are concerned that saw palmetto might cause erectile dysfunction, ejaculatory disturbance, or altered libido because of its potential effects on 5-alpha-reductase. Some preliminary clinical studies have reported sexual dysfunction, particularly ejaculatory dysfunction, erectile dysfunction, and reduced libido, in patients taking saw palmetto (5093,17202,17684,73383,89441). However, most of these patients were previously diagnosed with prostate disorders, so causality is unclear. Additionally, several clinical studies indicate that the occurrence of impotence in males taking saw palmetto is similar to placebo and tamsulosin (Flomax), and significantly less than finasteride (Proscar) (2732,6424,17306,107481). Rarely, cases of testicular pain, vesical tenesmus, and urinary tract infections have been reported in patients using saw palmetto extract orally (73388).

Hematologic ...Saw palmetto might have antiplatelet effects and potentially increase the risk of bleeding in some patients. There is one report of excessive intraoperative bleeding in a patient who took saw palmetto prior to surgery. Bleeding time normalized when saw palmetto was discontinued (8659). Also, one case of cerebral hemorrhage has been reported, but details are not available to determine causality (6772,73348). A case of retroperitoneal hematoma after bilateral inguinal hernia repair is reported in a male patient taking saw palmetto. The patient was discharged after a 3-day hospitalization in stable condition (112177).

Hepatic ...A case report describes a patient who developed acute hepatitis and pancreatitis while taking saw palmetto. Symptoms resolved when saw palmetto was discontinued, and reemerged upon re-challenge (14457). Other cases of acute hepatitis and pancreatitis, with elevated alkaline phosphatase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and bilirubin have been reported in patients using saw palmetto orally (14457,73350,73351).

Musculoskeletal ...Orally, saw palmetto may cause fatigue, weakness, muscle pain, and back pain, although these adverse events are rare (6424,73388,89441). A case of saw palmetto-related rhabdomyolysis was reported in an 82-year-old male presenting with kidney dysfunction, increased C-reactive protein levels, and elevated serum creatine kinase (73358).

Neurologic/CNS ...Orally, saw palmetto can cause headaches, dizziness, insomnia, and fatigue (6750,6752,6772,11354,60442,73348,73385,73388,89441).

Ocular/Otic ...A case of intraoperative floppy-iris syndrome (IFIS) has been reported in a patient using saw palmetto orally (73340). However, no statistically significant association between saw palmetto and IFIS was found in a case series of 660 patients undergoing cataract surgery (73347).

Pulmonary/Respiratory ...Rhinitis is one of the more commonly reported adverse effects of saw palmetto (73348). One patient taking saw palmetto extract 160 mg twice daily reported "breathlessness" (73388). Two cases of respiratory depression have been reported in patients using saw palmetto extract (Permixon) 320 mg (6772).

(Read more about SAW PALMETTO)

General ...Orally, stinging nettle seems to be generally well tolerated.
Most Common Adverse Effects:
Orally: Constipation, diarrhea.
Topically: Contact with the raw plant causes itching, rash, and stinging.

Dermatologic ...Topically, fresh stinging nettle leaves and stalk can cause localized rash, itching, and stinging (12490,76399,76412,76414,76417,76428,76448,96746). Usually, short exposure to stinging nettle results in a transient urticarial reaction and a stinging sensation which may persist for more than 12 hours (76399,76414,76417,96746). In one report, a patient placed a fresh stinging nettle leaf on the tongue to suck out the sap of the leaf. Severe tongue edema, pain, and urticaria developed within 5 minutes. Symptoms continued for several hours after the leaf was removed (15197). In another case report, a young couple intoxicated with methamphetamine fell and laid in a stinging nettle bush for 20 minutes, after which urticaria and pain continued for 2-3 weeks, and a heightened sensitivity to cold persisted for several months (96746).

Endocrine ...A case of gynecomastia has been reported for a 33-year-old male who consumed stinging nettle tea 2 cups daily for one month prior to symptom onset. The condition subsided one month after discontinuing stinging nettle tea (76410).
There have been two cases of galactorrhea associated with the consumption of stinging nettle for one month (76410,108902). In one case, a 33-year-old female consuming stinging nettle tea showed high levels of estradiol and low levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH). The levels of these hormones normalized 6 weeks after discontinuing stinging nettle tea (76410). In the other case report describing a 30-year-old female self-treating with stinging nettle 500 mg daily, hormone levels were not reported; however, a mammogram showed scattered areas of fibroglandular density and benign-appearing calcifications. This patient had complete resolution of symptoms 1 week after discontinuation of stinging nettle (108902).

Gastrointestinal ...Orally, stinging nettle root can cause gastrointestinal complaints, including diarrhea and constipation (1,7,11230). Stinging nettle above ground parts may cause mild gastrointestinal discomfort when taken on an empty stomach (7035). Stinging nettle juice may cause diarrhea (1). One patient taking a combination product containing stinging nettle root extract and pygeum bark extract (Prostatonin, Pharmaton) experienced continual gastrointestinal pain and hyperperistalsis. It is not clear if this effect was due to stinging nettle or pygeum (70230).

Genitourinary ...There is a case report of decreased ejaculatory volume associated with an herbal blend product containing stinging nettle root extract, saw palmetto extract, pumpkin seed oil extract, lemon bioflavonoid extract, and beta-carotene (5093). It is unclear if this was due to stinging nettle, other ingredients, or the combination.

Hepatic ...A case of idiosyncratic drug-induced liver disease (DILI) is reported in a 36-year-old female who presented with abdominal pain after 1 month of taking an herbal liver detox tea containing stinging nettle and other ingredients. Remarkable laboratory values included elevated liver enzymes, alkaline phosphatase, and total bilirubin. The patient received a loading dose of N-acetylcysteine and was hospitalized for 12 days (112178). However, it is unclear if the adverse effect was due to the stinging nettle, other ingredients, or the combination.

Other ...Orally, stinging nettle root can cause sweating (1,7).

(Read more about STINGING NETTLE)

General ...Orally, there is limited information available about the adverse effects of yohimbe. Yohimbine, a constituent of yohimbe, might be unsafe; most reported adverse effects are dose-related.
Most Common Adverse Effects:
Orally: Yohimbine, a constituent of yohimbe, has been associated with anxiety, agitation, diaphoresis, diarrhea, flushing, headache, hypertension, increased urination, nausea, tachycardia, tremors, vertigo, and vomiting.
Serious Adverse Effects (Rare):
Orally: Yohimbine, a constituent of yohimbe, has been associated with atrial fibrillation, hypertensive crisis, myocardial infarction, and QT interval prolongation.

Cardiovascular ...Orally, yohimbine, a constituent of yohimbe, has been associated with hypertension, especially at higher doses (3312,17465,86801,86802,86804,86811,86820,86822,86834,86856)(86786,86896). A case of hypertensive crisis was reported in a 63-year-old male taking a yohimbine-containing herbal product once daily for one month. The patient was successfully managed with intravenous nitroprusside followed by clonidine (91521). Tachycardia, fluid retention, palpitations, and chest discomfort have also been reported (3312,17465,86786,86793,86801,86802,86804,86822,86843,86854)(86856,86866,86867,86869,86871,86874,86875). Conduction abnormalities have also been reported (86856,86786). There have been some reports of myocardial infarction, atrial fibrillation, and QT interval prolongation (17465). In theory, these effects may also occur with the use of yohimbe bark extract.

Dermatologic ...Orally, yohimbine, a constituent of yohimbe, may cause rash, erythrodermic skin eruption, and exanthema (3312,3971,86804,86896,86878).

Gastrointestinal ...Orally, yohimbine, a constituent of yohimbe, may cause nausea, vomiting, increased salivation, diarrhea, and gastrointestinal distress (3970,17465,49902,86780,86781,86786,86801,86804,86824,86827)(86828,86829,86863,86878,86882,86896).

Genitourinary ...Orally, yohimbine may cause dartos contraction or decreased libido in some patients (86786,86882). A case of severe intractable priapism has been reported for a 42-year-old male who took a supplement containing yohimbe extract the previous day for sexual enhancement. Treatment with phenylephrine 400 mcg was unsuccessful at resolving the priapism, so surgical insertion of a proximal cavernosal spongiosum shunt was needed (86804).

Hematologic ...A case of drug-induced agranulocytosis has been reported following prolonged use of oral yohimbine, a constituent of yohimbe (86877).

Immunologic ...There is one report of a hypersensitivity reaction including fever; chills; malaise; itchy, scaly skin; progressive renal failure; and lupus-like syndrome associated with ingestion of a one-day dose of yohimbine, a constituent of yohimbe (6169).

Musculoskeletal ...Orally, yohimbine, a constituent of yohimbe, may cause muscle aches (86850).

Neurologic/CNS ...Orally, yohimbine, a constituent of yohimbe, has been associated with reports of general central nervous system (CNS) and autonomic excitation, tremulousness, head twitching, seizure threshold changes, enhanced brain norepinephrine release, decreased energy, dizziness, vertigo, and headache (3312,3971,86774,86779,86786,86804,86827,86857,86870,86882)(86883). Cold feet and chills have also been reported with yohimbine (86827,86896). Other adverse reactions include flushing and diaphoresis (17465). Excessive doses of yohimbine can also cause paralysis (11,18). A case of acute neurotoxicity characterized by malaise, vomiting, loss of consciousness, and seizures has been reported for a 37-year-old bodybuilder who ingested a single dose of yohimbine 5 grams. Improvement was seen within 12 hours following treatment with furosemide, labetalol, clonidine, urapidil, and gastrointestinal decontamination (86801).

Psychiatric ...Orally, yohimbine, a constituent of yohimbe, may increase malaise, fatigue, insomnia, restlessness, agitation, and anxiety (3312,3970,3971,17465,86786,86801,86804,86822,86827,86834)(86868,86878,86882,86896). In a clinical study of healthy subjects, administration of yohimbine increased impulsivity, with larger doses increasing impulsivity more than 50% (86784,86810).

Pulmonary/Respiratory ...Orally, yohimbine, a constituent of yohimbe, may cause bronchospasm, tachypnea, cough, and rhinorrhea (17465,86825,86850). A case of sinusitis characterized by pain and discomfort above both eyes has been reported for a 59-year-old male taking yohimbine 5.4 mg three times daily to treat erectile dysfunction. Symptoms resolved within 24 hours of discontinuing yohimbine. The effect was attributed to the alpha-2 adrenergic antagonist effects of yohimbine (94112). Excessive doses of yohimbine can cause respiratory depression (1118).

Renal ...Orally, yohimbine, a constituent of yohimbe, may increase urinary frequency (3312,3970,3971,17465,86804,86827,86850,86861,86882). A case of acute renal failure has been reported for a 42-year-old male taking yohimbine. Normalization of renal function was achieved following 2 weeks of treatment with corticosteroids. The renal dysfunction was attributed to yohimbine-induced systemic lupus erythematosus (6169).

(Read more about YOHIMBE)