After a review of the scientific evidence for the most common ingredients found in over-the-counter dietary supplements to improve male sexual health, researchers from Wake Forest Baptist Medical Center concluded they “do not routinely recommended these products.” Findings from the study are published in the Journal of Sexual Medicine.

Over-the-counter (OTC) dietary supplements for sexual enhancement contain everything from horny goat weed to ginseng. Study authors reviewed these common ingredients to see if they were effective and safe. They evaluated current available evidence for each of the ingredients to provide a guide for for urologists when counseling their patients.

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Some products had no scientific backing to support claims about enhancements in erectile function, libido, and sexual performance. Also, some products marketed as being “natural” were found to contain traces of phosphodiesterase-5-inhibitors (PDE5Is), which are found in prescription drugs such as Viagra (sildenafil) used to treat erectile dysfunction. A separate study found that 81% of OTC samples tested from the U.S. and Asia contained PDE5Is. Patients with advanced heart disease, or those who take nitrates (eg, nitroglycerin), should not use PDEI5s as they may drop blood pressure to unsafe levels. Also, men with severe hepatic impairment or end-stage renal disease requiring dialysis should not use PDE5Is. 

Purity was also a concern with the dietary supplements. Since they are categorized as foods, not drugs, manufacturers are responsible for assuring the product’s safety, purity, and efficacy. 

Here is a summary of results on ingredients found in top-selling products:

  • DHEA: no signficant impact on hormone levels; evidence is weak to suggest benefit.
  • Fenugreek: relatively safe supplement; one study point to improved sexual arousal, orgasm, muscle strength and energy.
  • Gingko biloba: no evidence to show improvement in erectile dysfunction. Caution in patients on warfarin as concomitant use may potentiate bleeding. May also cause headaches and seizures. 
  • Ginseng: included often in men’s supplements. GI upset, headache, rash, insomnia may occur. For patients with diabetes, ginseng has been shown to lower blood sugar so caution should be used in this patient population.
  • Horny Goat Weed: no evidence of sexual function benefit; rare reports of toxicity (increased heart rate, hypomania).
  • L-arginine: common amino acid used in supplements and may possibly be beneficial in improving erectile function. May also lower BP without significant changes in heart rate.
  • Maca: may increase sexual behavior though research is limited in animals. Rare reports of toxicity (increased LFTs and BP)
  • Tribulus: liver and kidney toxicity has been reported with high doses; no evidence of human benefit.
  • Yohimbine: drug has been used for a long time and has shown promise in male sexual function. Side effects include hypertension, insomnia, sweating, agitation and headache.
  • Zinc: no evidence of benefit but appears to be safe.

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