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Online ED Supplements: Buyer Beware

Two big problems with erection aids sold online: Low doses and bogus reviews

Key points

  • Online erection supplements often contain ingredients of questionable value at doses too low to have any effect.
  • Many online reviews for erection supplements appear to be fake.
  • To improve erections, start with lifestyle modifications.

In a previous post, I discussed research showing that online offers for Viagra and other erection drugs rarely contain pharmacologically active doses of the drugs, if any of the drugs at all. Now a study shows that online erection supplements should also be avoided. They often contain herbs and other substances of questionable value. If supplement ingredients have been shown to help with erections, the doses in online products are typically way too low to have much effect. And most of the breathless five-star reviews appear to be fake.

Researchers at Baylor College of Medicine in Houston and the University of Utah in Salt Lake City searched “erectile dysfunction” on and then purchased and analyzed the top six supplement products the site identified.

The Supplements: Are They Effective?

Typically, erection supplements contain a smorgasbord of up to 20 ingredients. In Amazon’s top six products, the four most popular ingredients include three medicinal herbs (ginseng, horny goat weed, and tongkat), and the amino acid (L-arginine).

Here’s what you should know about them:

Giseng (Panax ginseng, P. quinquefolius). For centuries, Asians have considered the root of this groundcover a sex enhancer. Some evidence suggests it increases blood levels of nitric oxide, a compound critical to erection. Korean researchers gave 45 ED sufferers a placebo or Korean red ginseng. This form of the herb starts with the peeled root, then steam heats and sun dries it (900 mg three times a day, total 2,700 mg/day). The ginseng group experienced significantly greater erection improvement. But most erection supplements contain much less than the 2,700 mg dose used in the study. Check labels for dosage.

Horny goat weed (Epimedium, various species). Legend has it that ages ago, a Chinese goat herder noticed that after eating this plant, the males in his flock became more sexually active, hence the herb’s common name. This plant contains icariin, a chemical cousin of the active ingredient in Viagra (sildenafil). But gram for gram, icariin is much less potent than sildenafil. One study in rats shows erection enhancement, but animal results may or may not apply to humans, No human trials have been published. If the herb is as effective in men as in rats, the typical man would need at least 1,000 mg of icariin a day. Most supplements contain much less. Check labels.

Tongkat (Eurycoma longifolia). Tongkat, or tongkat ali, is the root of a plant native to Southeast Asia, where it has been used medicinally for centuries. Some studies suggest it increases blood levels of testosterone. But testosterone usually affects only libido, not erections or sexual function. Other studies have shown improvements in sperm quality and motility at 300 mg/day. Again, fertility enhancement may or may not impact sexual function. Malaysian researchers analyzed 11 studies of tongkat for erectile dysfunction (ED). Seven showed some benefit—but only for men with severe ED. Four showed no benefit for anyone.

L-arginine. The amino acid, L-arginine, is the precursor of nitric oxide. Several studies show that supplementation helps treat ED. University of Hawaii researchers gave a placebo or ArginMax, a supplement containing L-arginine, ginseng, and ginkgo (below), to 52 men with ED. A month later, 24 percent of the placebo group reported improvement, but in the ArginMax group, 84 percent.

ArginMax may also improve the effectiveness of erection drugs. Researchers at the University of California, Davis, told ED sufferers disappointed with Viagra to try the drug with either a placebo or ArginMax. After four weeks, 22 percent of those taking the placebo reported improvement; the ArginMax group, 60 percent. L-arginine is available at supplement outlets.

South Korean researchers analyzed 10 studies of arginine for ED that used doses of 1,500 to 5,000 mg/day. Compared with placebo treatment, supplementation “significantly improved ED.”

All of these supplements may cause side effects, and some men shouldn’t take them. Check the Internet for details, or consult your physician and pharmacist.

Bottom line: Erection supplements may improve firmness, but don’t count on it. Doses are usually too low for significant benefit. And if you obtain benefit, don’t expect too much.

The Hype: Often Fake

Erection-enhancement products on Amazon come with what purport to be customer reviews. But many reviews appear to be questionable or fake. The researchers analyzed all product reviews using a tool called ReviewMeta, which analyzes a dozen aspects of reviews, and claims to be able to distinguish the real from the bogus. (The ReviewMeta site explains the process more fully.) After ReviewMeta filtration, here’s what the researchers found:

  • Only 23 percent of reviews reliably indicated improved erection firmness.
  • Only 17 percent showed actual ability to maintain firm erections.
  • Only 10 percent suggested honestly increased sexual satisfaction.

Buyer Beware

You’re free to buy any sex supplements you want. They may help. But is it the supplement? Or the placebo effect? Give anyone any purported medicine for any condition, and around one-third claim benefit. For sexual supplements, the placebo effect may be considerably greater.

My advice: Start with lifestyle modifications, not supplements. Many studies show that exercise, diet changes, and relaxation therapies, notably yoga, help sexual function. (For more on this, click here.)

Then, instead of combination supplement products that typically offer low doses of many ingredients, take one supplement at a time at evidence-based dosages—for example, 2,700 mg/day of Korean red ginseng, or at least 1,500 mg/day of L-arginine. Experiment with dosage, and note your cost and any side effects. That way you can get a reasonable idea of each substance’s cost-effectiveness and tolerability. Then take two supplements together, and eventually perhaps more. Over six months or so, you should be able to discover what dose of which supplement(s) help(s) you—if any.


Balasubramanian, A. et al. “An Analysis of Popular Online Erectile Dysfunction Supplements,” Journal of Sexual Medicine (2019) 16:843.

Choi, Y.D. et al. “Effects of Korean Ginseng Berry Extract on Sexual Function in Men with Erectile Dysfunction: A Multicenter Placebo-Controlled, Double-Blind Clinical Study,” International Journal of Impotence Research (2013) 25:45.

Corazza, O. et al. “Sexual Enhancement Products for Sale Online: Raising Awareness of the Psychoactive Effects of Yohimbine, Maca, Horny Goat Weed, and Ginkgo Biloba,” Biomedical Research International (2014) 2014:841798.

Dell’Agli, M. et al. “Potent Inhibition of Human Phosphodiesterase-5 by Icariin Derivatives,” Journal of Natural Products (2008) 71:1513.

Ito, T. et al. “The Effects of ArginMax, a Natural Dietary Supplement, for Enhancement of Male Sexual Function,” Hawaii Medical Journal (1998) 57:741.

Thu HE et al. “Eurycoma Longifolia as a Potential Adoptogen of Male Sexual Health: A Systematic Review of Clinical Studies,” Chinese Journal of Natural Medicine (2017) 15:71.

Kotirum, S. et al. “Efficacy Of Tongkat Ali (Eurycoma Longifolia) On Erectile Function Improvement: Systematic Review And Meta-Analysis Of Randomized Controlled Trials,” Complementary Therapies in Medicine (2015) 23:693.

Rhim, H.C. et al. “The Potential Role of Arginine Supplements on Erectile Dysfunction: A Systemic Review and Meta-Analysis,” Journal of Sexual Medicine (2019) 16:223.

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