Horny Goat Weed Benefits for Men: What the Research Actually Shows

Short answer: The best documented horny goat weed benefits in people are modest and narrow: one 24-month randomized trial found that epimedium flavonoids helped preserve bone density in postmenopausal women. The benefits most men are curious about (sexual function, drive and testosterone) rest mainly on rat, mouse and test tube studies, and a 2022 review stated that no human data was available for icariin itself. Horny goat weed appears well tolerated at ordinary doses, but it has real drug interactions and rare high-dose reports, so check with a clinician if you take heart or blood pressure medicines.

Key Takeaways

• Horny goat weed is the common name for Epimedium, a plant genus used in traditional Chinese herbal practice. Its most studied compound is the flavonoid icariin.
• The strongest human evidence is for bone density in postmenopausal women (one double-blind trial of 100 women over 24 months). There is no comparable trial in men.
• Sexual function and testosterone findings come almost entirely from animal and lab research. Small human trials of multi-ingredient products have been mixed.
• There is no established dose. The bone trial used a flavonoid extract supplying 60 mg of icariin daily; raw herb weight on a label is not the same as icariin content.
• Reported side effects include upset stomach, dry mouth and dizziness. Irregular heartbeat, low blood pressure and mood changes have been reported in some people, and one published case of hypomania exists.
• Do not combine it with nitrate medicines (such as nitroglycerin) without medical advice, and talk to a doctor if you have heart disease, a hormone-sensitive condition or take blood thinners.

What Is Horny Goat Weed (Epimedium)?

Horny goat weed is a group of low-growing flowering plants in the genus Epimedium. In Chinese herbal tradition it is called yin yang huo, and it has been used for centuries for low libido, fatigue and joint complaints.^[5] The English nickname comes from a folk story about goats becoming more active after grazing on the plant. It makes a good story, but it is not evidence.

The leaves contain several hundred constituents.^[1] The one researchers focus on is icariin, a flavonoid glycoside. Epimedium also contains other flavonoids and plant compounds with weak estrogen-like activity (phytoestrogens), which matters for safety in people with hormone-sensitive conditions.^[6]

Icariin is not the same as “epimedium” on a label

Products list either raw herb or extract, sometimes standardized to a percentage of icariin. Two capsules that both say “epimedium” can deliver very different amounts of icariin. When you compare products or read a study, check whether the number refers to the whole herb, an extract, or purified icariin. Our guide on how to read supplement labels walks through this in more detail.

Horny Goat Weed Benefits: What the Evidence Shows

The quickest way to understand horny goat weed is to separate what has been tested in people from what has only been seen in animals or cells. The table below sums it up.

Bone density: the clearest human result

A trial published in the Journal of Bone and Mineral Research randomized 100 women who were 10 to 18 years past menopause and had low bone density.^[2] Half took an epimedium flavonoid extract supplying 60 mg icariin, 15 mg daidzein and 3 mg genistein per day; half took placebo. Everyone received 300 mg of calcium daily. After 24 months, the placebo group lost 2.4% of lumbar spine bone density, while the extract group held steady, and the difference between groups was statistically significant. Endometrial thickness and estradiol did not change in either group. It is a single trial in women, so it says nothing direct about men, but it is the most solid human data on this plant.

Sexual function: promising in rats, unproven in men

A 2022 narrative review in Translational Andrology and Urology pulled together the research on icariin and erectile function.^[3] Its findings came from rodent models of diabetes, nerve injury, aging and toxic exposure, plus cell work, and it stated plainly that no human data was available for icariin. The animal doses were also large on a body weight basis, so they do not translate neatly into a capsule.

Human trials have tested blends, not epimedium alone. LiverTox, the US government database on liver safety, summarizes a 2012 crossover trial of a five-ingredient product in 63 men with mild to moderate erectile complaints that found only slight improvement, and a 2014 trial of a multi-ingredient product in 49 older men that found no difference in sexual function or hormone levels versus control.^[1] With several herbs in each product, neither trial can tell you what epimedium alone does. WebMD’s overview likewise calls the evidence for sexual benefits preliminary.^[6]

Testosterone: animal data only

Rodent and Leydig cell experiments report higher testosterone and increased activity of enzymes used to make steroid hormones after icariin or its metabolites.^[3] That is a reason for researchers to keep looking, not proof that a supplement will change a man’s blood work. If you suspect low testosterone, a morning blood test is the place to start; see our pages on signs of low testosterone and other herbs studied for testosterone.

How Icariin Is Thought to Work

In lab studies, icariin inhibits an enzyme called phosphodiesterase type 5 (PDE5), which breaks down a signaling molecule involved in relaxing smooth muscle in blood vessels.^[3] Researchers have also built synthetic icariin derivatives that are far more active in these test tube assays than the natural compound.

Two caveats keep this in perspective. First, test tube activity does not tell you what happens after you swallow the herb. The 2022 review notes that icariin is poorly absorbed and that gut bacteria convert most of an oral dose into a different compound, icariside II, before it reaches the blood.^[3] Second, the plant’s phytoestrogens and other constituents may act on hormones in ways that are not fully mapped.

Horny Goat Weed Dosage

There is no established or official dose for horny goat weed.^[6] WebMD advises following the product label or your provider’s advice.^[5] Useful reference points:

• Research dose: the 24-month bone trial used an extract delivering 60 mg icariin per day, alongside two soy isoflavones.^[2]
• Herb versus extract: a label listing a few hundred milligrams of whole herb does not tell you the icariin content unless the extract is standardized.
• Quality: WebMD reports that some products sold for sexual performance have been found to contain undeclared prescription drugs, including one that led to an FDA recall.^[5] Buy brands that disclose amounts and test their products; our guide to third-party tested supplements explains what to look for.

Horny Goat Weed Side Effects and Safety

At ordinary doses, horny goat weed appears to be well tolerated in the short term.^[1][6]

Common, mild effects

• Upset stomach, nausea and abdominal discomfort^[1][5]
• Dry mouth and dizziness or vertigo; alcohol may make dizziness worse^[5]
• Rare skin rash or allergic dermatitis^[1]

Less common but more serious reports

• Heart rhythm and blood pressure: irregular heartbeat, low blood pressure and nosebleeds have been reported in some people.^[6] In the 2012 multi-ingredient trial, a few participants reported a fast heart rate and dizziness.^[1]
• Mood: a 2018 systematic review of mania linked to herbal medicines found one published case of hypomania associated with horny goat weed; the original authors suggested other unidentified ingredients may have played a role, but this was not tested.^[4]
• High doses: WebMD reports that high doses have been linked to spasms and breathing problems.^[6]
• Liver: LiverTox rates horny goat weed as an unlikely cause of clinically apparent liver injury. The rare liver cases on record involved multi-ingredient products where the role of epimedium was unclear.^[1]

Who Should Avoid Horny Goat Weed or Ask a Doctor First

• People taking nitrate medicines such as nitroglycerin or isosorbide, or using amyl nitrite: WebMD describes this combination as potentially dangerous because of severe drops in blood pressure.^[5][6]
• People taking prescription erectile or pulmonary hypertension medicines, which WebMD lists as a possible interaction.^[5]
• People on blood thinners, aspirin, blood pressure medicines or antidepressants.^[6]
• Anyone with heart problems, prostate problems or a hormone-sensitive cancer, because of the plant’s phytoestrogens.^[5]
• Pregnant or breastfeeding women and children.^[6]

Persistent erection problems, low drive or fatigue can be early signs of cardiovascular disease, diabetes or a hormone problem. A doctor’s visit is the right first step, not a supplement.

Epimedium in Ultra Bann

Ultra Bann, a natural male vitality supplement by DL Bioproducts, lists epimedium (horny goat weed) at 45 mg per serving as one of seven botanicals, alongside Thai Butea superba (345 mg), Panax ginseng (110 mg), Cynomorium songaricum (85 mg), black ginger (85 mg), tongkat ali (85 mg) and reishi (45 mg), for 800 mg total. Every amount is on the label, with no proprietary blend, and the serving is one capsule every 2 days. You can read the full label on the Ultra Bann ingredients page and learn about other ingredients in our guides to Panax ginseng and tongkat ali. The safety and interaction points above apply to any product that contains epimedium, so check with your doctor if any of them fit you. If you want to try it, you can order Ultra Bann here; first orders include free US shipping and a 60-day money-back guarantee.

Frequently Asked Questions

What are the main horny goat weed benefits for men?

For men specifically, no benefit has been confirmed in well designed human trials of epimedium alone. Interest centers on sexual function and testosterone, but that evidence comes from animal and lab studies. The best human result so far is bone density protection in postmenopausal women.

How long does horny goat weed take to work?

There is no reliable answer, because there is no established dose and no strong human trial in men to measure against. The bone trial measured results at 12 and 24 months. Be wary of products that promise fast effects, since some fast acting “herbal” products have been found to contain hidden prescription drugs.

Is it safe to take horny goat weed every day?

Short term use at ordinary doses appears well tolerated for most healthy adults, and the bone trial ran daily for 24 months. Long term safety in men has not been studied in depth. Stop and get help if you notice a racing or irregular heartbeat, wheezing or fainting.

Does horny goat weed raise testosterone?

Rodent and cell studies suggest it may, but a 2022 review found no human testosterone data for icariin, and a trial of a multi-ingredient product in older men found no hormone change. A blood test is the only way to know your own levels.

Can I take horny goat weed with blood pressure medicine?

Ask your doctor first. Horny goat weed has been linked to low blood pressure and irregular heartbeat in some people, and combining it with nitrate medicines may cause a dangerous drop in blood pressure.

References

1. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Horny Goat Weed. National Institute of Diabetes and Digestive and Kidney Diseases; updated 2022. ncbi.nlm.nih.gov/books/NBK583203
2. Epimedium-derived phytoestrogen flavonoids exert beneficial effect on preventing bone loss in late postmenopausal women: a 24-month randomized, double-blind and placebo-controlled trial. Journal of Bone and Mineral Research. 2007;22(7):1072-9. PubMed 17419678
3. Niu Y, Lin G, Pan J, et al. Deciphering the myth of icariin and synthetic derivatives in improving erectile function from a molecular biology perspective: a narrative review. Translational Andrology and Urology. 2022;11(7):1007-1022. tau.amegroups.org
4. Bostock E, et al. Mania associated with herbal medicines, other than cannabis: a systematic review and quality assessment of case reports. Frontiers in Psychiatry. 2018. frontiersin.org
5. Horny Goat Weed: uses, side effects and interactions. WebMD; reviewed 2025. webmd.com
6. Horny Goat Weed (Epimedium). WebMD. webmd.com

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. This article is for information only and is not medical advice.