Over-the-counter dietary supplements and therapies sold to improve male sexual health may be ineffective and even unsafe, says a report published in the Journal of Sexual Medicine.

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Many men turn to OTC supplements to tackle sexual health problems.

Around 40-70% of men experience sexual dysfunction at some time.

To avoid paying for prescription drugs, or the embarrassment of discussing such matters with their physicians, many turn to over-the-counter (OTC) products.

Sales of dietary supplements doubled in the US from 1999-2007, and around 50% of Americans use them for a variety of conditions.

The dazzling array of products, from horny goat weed to ginseng, costs from $0.83 to $5.77 per day. But lack of regulation on dosage, purity or ingredients, and limited information regarding health effects confuses patients and medical practitioners alike.

Researchers from Wake Forest Baptist Medical Center in Winston-Salem, NC, reviewed the scientific evidence for the effectiveness and safety of the most common ingredients in top-selling men’s health products.

They wanted to provide urologists with a guide for counseling patients who present with sexual health problems and who are taking such supplements.

There was no scientific evidence to support claims that many products positively impact erectile function, libido and sexual performance, and some were likely to be unsafe.

Some products advertised as “natural” contain traces of phosphodiesterase-5-inhibitors (PDE5Is), the same class of medication that includes prescription drugs such as Viagra, which is used to treat erectile dysfunction. PDE5Is cannot be legally sold over the counter in the US, because using them without a physician’s supervision could be risky.

Patients with advanced heart disease or who take nitrates, such as nitroglycerin, should not use PDE5Is, as it may cause an unsafe drop in blood pressure.

PDE5Is should also be avoided by men with severe liver impairment or end-stage kidney disease. Those with enlarged prostates who take medications such as Flomax (tamsulosin), terazosin or doxazosin should only take it with supervision, as interactions may cause dizziness, leading to falls and fractures.

In one study, 81% of OTC products purchased in the US and Asia contained PDE5Is.

The findings on some of the best-selling products can be summarized as follows:

  • DHEA is a hormone naturally made by the human body and produced in laboratories from chemicals found in wild yam and soy. While findings do not suggest a benefit, it appears to be relatively safe, as the impact on hormone levels is not significant
  • Fenugreek features in 1 in 3 top-selling men’s health supplements. It may improve sexual arousal and orgasm, muscle strength, energy and well-being. There was no evidence of adverse effects
  • Ginkgo biloba is taken for numerous conditions, but data does not support its use in erectile dysfunction. It can cause headache, seizures and significant bleeding, especially if taken alongside Coumadin
  • Ginseng is the most common ingredient in top-selling men’s health supplements; it can cause headache, upset stomach, constipation, rash and insomnia. It can also lower blood sugar, risky in cases of diabetes
  • Horny Goat Weed is generally safe with rare reports of toxicity leading to fast heart rate and hypomania; it has no apparent benefit for sexual function
  • L-arginine is the top amino acid in men’s health supplements, featuring in 1 in 3 best sellers. It may improve erectile function in some patients and seems relatively safe. It has been associated with a drop in blood pressure but without significantly changing the heart rate
  • Maca is the most common vegetable among top-selling men’s health supplements. Maca has been associated with increased sexual behavior in animals but not in humans. Rare cases of toxicity and a mild increase in liver enzymes and blood pressure have been reported.

Tribulus promises to treat a range of conditions, but evidence is lacking to prove its effectiveness; two young men suffered liver and kidney toxicity after taking high doses. Yohimbine is a well-established product that may improve male sexual function, but it can also cause hypertension, headache, agitation, insomnia and sweating. Zinc appears to be safe but not beneficial.

Purity is a concern. Because dietary supplements are currently classified as foods rather than drugs, the manufacturers themselves are largely responsible for ensuring the safety, purity and efficacy of the products.

Four major retailers have recently been targeted by the New York attorney general for selling misleading or adulterated dietary supplements.

Dr. Ryan Terlecki, associate professor of urology and senior author, says:

“While certain natural supplements we reviewed show promise for improving mild sexual dysfunction, they lack robust human evidence.”

Dr. Terkecki adds that his team is unlikely to recommend the products to patients due to concerns that they are impure or ineffective.

Medical News Today has also reported that eating more fruit can help prevent erectile dysfunction.