Horny Goat Weed: Does It Work? - Healthline

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Key takeaways

Horny goat weed contains icariin, a compound that may help improve blood flow to the penis by blocking an enzyme that restricts erections. While it works similarly to medications like Viagra, studies suggest it is significantly less potent.
Research on horny goat weed is limited, but some studies indicate potential benefits for erectile function. A 2010 animal study showed improved erectile function in rats, and a 2021 review identified icariin as a potentially effective plant-based option for ED.
If you’re considering horny goat weed, consult with a healthcare professional to determine the correct dosage for you, and discontinue use if you experience any unusual side effects. People with heart conditions, high blood pressure, or hormone-sensitive cancers should avoid horny goat weed.

Horny goat weed is an over-the-counter herbal supplement. The active ingredient is icariin, an extract of the Epimedium plant that’s reported to benefit people with erectile dysfunction (ED).

It’s also known as:

yin yang huo
barrenwort
rowdy lamb herb
randy beef grass

It’s sold in many different forms, including:

tablets
capsules
powders
teas

How is horny goat weed said to work for people with ED?

Erections usually occur after nitric oxide signals a chemical called cyclic guanosine monophosphate (cGMP) to relax the smooth muscle of the penis. This triggers an influx of blood into three tube-like cylinders in the penis.

With ED, an enzyme named protein phosphodiesterase type 5 (PDE5) interferes with nitric oxide and cGMP. As a result, the blood can’t move through the arteries and create an erection.

Icariin, the active ingredient in horny goat weed, inhibits the activity of PDE5. This allows blood to fill the arteries and the three cylinders in the penis to create an erection.

The prescription medication sildenafil (Viagra) works in much the same way.

What does the research say about horny goat weed and ED?

Research on the effects of horny goat weed on human erectile tissue is limited.

A 2008 test-tube study found that icariin effectively inhibits human PDE5, the substance that blocks erections. However, it also determined that sildenafil is 80 times more potent than icariin.

A 2010 animal study looked at the effects of horny goat weed on rats. Researchers found that rats treated with a purified extract showed improved erectile function.

A 2021 review of PDE5 inhibitors found that icariin is the most effective plant-based option for ED.

How much horny goat weed should you take for ED?

There isn’t a universal dosage or recommended serving size for horny goat weed. It ultimately varies depending on the individual product and manufacturer, so pay close attention to the directions on the label.

If you’re unsure about what dosage is right for you, consider seeking advice from a healthcare professional before use. They can make personalized recommendations based on your individual medical history.

Remember that results can vary from person to person. If you experience any side effects, discontinue use and consult a healthcare professional.

Are side effects or risks possible with horny goat weed?

According to Memorial Sloan Kettering Cancer Center, side effects include:

sweating or flushing
rapid heartbeat
increased energy
mood changes

You may be more likely to develop complications with horny goat weed if you have certain conditions or take certain medications. Do not use horny goat weed if you:

have heart disease
have high blood pressure
have a history of hormone-sensitive cancer
take medications that cause irregular heartbeat or thin your blood
are allergic or sensitive to plants in the Berberidaceae family

When to consult a doctor or other healthcare professional

It may be best to consult a healthcare professional if you’ve had difficulty developing or maintaining an erection several times over the course of a few weeks.

ED is common, especially with age. A healthcare professional can make or confirm an ED diagnosis, work with you to determine the underlying cause, and go over your options for treatment.

However, if you aren’t ready to discuss your concerns just yet, you can explore over-the-counter herbal supplements, like horny goat weed, as long as you stay within the manufacturer’s recommended dosage.

Discontinue use if you develop any unusual side effects, such as slower blood clotting or lowered blood pressure. This may indicate a negative interaction with other supplements or medications.

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The bottom line

The verdict is mixed on the effectiveness of horny goat weed. It appears to have some beneficial properties, but more research is needed to learn if it’s effective and safe for long-term use.

If you’re experiencing ED, consider talking with a healthcare professional about common treatment options.

Find Roman ED medication online.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Corazza O, et al. (2014). Sexual enhancement products for sale online: Raising awareness of the psychoactive effects of yohimbine, maca, horny goat weed, and ginkgo biloba.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4082836/
Dell’Agli M, et al. (2008). Potent inhibition of human phosphodiesterase-5 by icariin derivatives. http://pubs.acs.org/doi/pdf/10.1021/np800049y
El-Sakka AI. (2018). Dehydroepiandrosterone and erectile dysfunction: a review.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6119841/
Epimedium. (2023).https://www.mskcc.org/cancer-care/integrative-medicine/herbs/epimedium
Erectile dysfunction. (2024).https://www.niddk.nih.gov/health-information/urologic-diseases/erectile-dysfunction
Fang J, et al. (2017). Icariin, an anti-atherosclerotic drug from Chinese medicinal herb horny goat weed.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5644024/
Ganapathy AA, et al. (2021). Medicinal plants as a potential source of Phosphodiesterase-5 inhibitors: A review.https://www.sciencedirect.com/science/article/abs/pii/S0378874120334243?via%3Dihub
Koolwal A, et al. (2019). I-arginine and erectile dysfunction.https://journals.sagepub.com/doi/full/10.1177/2631831818822018
Lee HW, et al. (2021). Ginseng for erectile dysfunction.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8094213
Maiorino MI, et al. (2014). Lifestyle modifications and erectile dysfunction: what can be expected?https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291878/
Shindel AW, et al. (2010). Erectogenic and neurotrophic effects of icariin, a purified extract of horny goat weed (Epimedium spp.) in vitro and in vivo.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3551978/#__ffn_sectitle
Wang H, et al. (2022). The efficacy of acupuncture on patients with erectile dysfunction: a review.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9110168

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Medically reviewed by Kerry Boyle D.Ac., M.S., L.Ac., Dipl. Ac., CYT — Written by Susan York Morris — Updated on August 1, 2025

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Key takeaways

How is horny goat weed said to work for people with ED?

What does the research say about horny goat weed and ED?

How much horny goat weed should you take for ED?

Are side effects or risks possible with horny goat weed?

When to consult a doctor or other healthcare professional

Other frequently asked questions about horny goat weed

Does horny goat weed make your penis bigger?

What does horny goat weed do?

Are there any alternatives to horny goat weed?

The bottom line

How we reviewed this article:

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