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Horny Goat Weed vs. Viagra: Which Is Better for ED?

Mike Bohl, MD, MPH, ALM

Reviewed by Mike Bohl, MD

Written by Geoffrey C. Whittaker

Published 10/15/2020

Updated 03/04/2024

While natural supplements like horny goat weed sure sound like they’re going to help you to perform in the bedroom, a little digging makes one thing clear: between these supplements and legitimate medications approved by the U.S. Food and Drug Administration (FDA) to treat erectile dysfunction, there’s no comparison in safety and efficacy. 

Sexual performance supplements and other products touted as “natural Viagra®” make a lot of claims, but few if any are backed up by clinical trials. Generally, dietary supplements are held to different standards across the board when compared with FDA-approved medications. 

But that’s just scratching the surface.

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  • Horny goat weed is an informal name that’s used to refer to various herb species of the Epimedium genus. These herb species have been used in traditional Chinese medicine for centuries and are sometimes referred to as "yin yang huo."

  • Like with other herbal supplements, there’s limited evidence that horny goat weed offers any health benefits. Most of the research on this herb has been performed in labs under a microscope and not on humans.

  • Some research on animals suggests that icariin, a component in horny goat weed, might have positive effects on blood flow to the penis by inhibiting the effects of PDE5.

  • However, only a small amount of research compares horny goat weed to FDA-approved PDE5 inhibitors such as sildenafil.

Much more research on horny goat weed is needed before we can confidently state that it’s a worthwhile treatment for erectile dysfunction.

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Erections depend on a combination of proper nerve function and healthy blood flow. When you feel sexually aroused, your brain sends signals that promote the relaxation of the smooth muscles in the arteries that supply blood to your penis.

As blood flows into the erectile tissues of your penis, which are called the corpora cavernosa, a fibrous sheath called the tunica albuginea helps trap this blood, helping you sustain an erection during sexual activity.

One natural chemical that’s involved in this process is an enzyme called phosphodiesterase type 5, or PDE5.

PDE5 is found inside the smooth muscle cells of your blood vessels. It plays a key role in the control of blood flow. When the effects of PDE5 are inhibited, your blood vessels can relax and blood can more easily flow to certain parts of your body, including your penis.

Oral medications for erectile dysfunction, such as sildenafil (the active ingredient in Viagra), tadalafil (Cialis®), vardenafil (Levitra®) and avanafil (Stendra®) belong to a class of drugs referred to as PDE5 inhibitors.

These medications work by reducing the effects of PDE5 and making it easier for blood to flow into your penis when you’re sexually aroused.

You can learn more about this process, as well as the options available for improving blood flow to the penis, in our guide to the most common ED treatments and drugs.

Some research suggests that Epimedium grandiflorum, or horny goat weed, works like sildenafil (the active ingredient in Viagra). Horny goat weed may inhibit the effects of PDE5 and improve blood flow to certain parts of the body — including the penis. But unlike sildenafil, its risks aren’t as well understood.

Horny goat weed, a plant, is native to China and Korea. Its unique name can supposedly be traced back to a Chinese goat herder, who reportedly noticed increased sexual activity in his herd after they ate its leaves.

The name “horny goat weed” is a translation of the Chinese version, “yin yang huo,” as the herb has long been used in traditional Chinese medicine (TCM).

Horny goat weed has been used as an ingredient in traditional Chinese medicine for more than 1,000 years. It’s generally considered a yang tonic that enhances the “energetic organ” (kidney) and promotes fertility and sexual function.

In traditional Chinese medicine, epimedium has historically been used to treat cardiovascular health issues, including those that affect the circulatory system. It’s also purported to offer other benefits, like for osteoporosis.

Proponents of horny goat weed typically point to its active ingredient, icariin, as a source of its potential benefits.

It’s important to point out that most of the existing scientific research on horny goat weed has been carried out in a lab setting, usually under a microscope. A few studies have looked at its effects in animals, but human research is very limited.

Horny Goat Weed In Humans

When it comes to research involving humans, there isn’t very much to support horny goat weed as a treatment for any real diseases or health conditions.

However, a few studies have produced interesting findings. One human study involving elderly patients with vascular disease affecting blood flow to the heart and brain found improved blood circulation for those patients who were given epimedium compared to those who were not.

A double-blind, placebo-controlled study published in the Journal of Bone and Mineral Research in 2007 involving 100 post-menopausal women also found compounds derived from epimedium to help prevent bone loss over a 24 month period.

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Even though horny goat weed is one of the most popular ingredients in sexual health supplements, there’s very little high quality research showing that it treats ED.

A few animal studies have supported the theory that horny goat weed helps to improve erectile function by inhibiting PDE5, but more research is needed to confirm this hypothesis.

In 2013, a double-blind, placebo-controlled study published in the African Journal of Traditional, Complementary and Alternative Medicines found that a supplement containing epimedium had positive effects on men’s erections and sexual performance.

However, the supplement used in this study also contained several other ingredients, making it impossible to know whether the benefits were caused by horny goat weed, by another ingredient or by a combination of active ingredients.

Other research has suggested that icariin, the active ingredient in horny goat weed, may improve erectile function based on findings seen in castrated rats.

This research is interesting, and certainly promising. However, it’s important to keep in mind that substances that are effective at treating ED or another medical condition in animals don’t always have the same benefits in humans.

It’s also important to keep in mind that the anecdotal reports you can often find in blog posts and online reviews of horny goat weed don’t necessarily mean that it’s an effective option for treating ED or improving blood flow.

In other words, we need more studies -- and more importantly, higher quality research -- before we can confidently say that horny goat weed offers any serious benefits for erectile dysfunction or other male sexual performance issues.

Like other supplements, horny goat weed may cause side effects. Reported adverse effects of horny goat weed extract and its active ingredients include:

  • Nausea

  • Abdominal discomfort

  • Irregular heartbeat

Currently, there are no long-term toxicity studies that look at the safety of horny goat weed or its active ingredient icariin. However, research suggests that some horny goat weed extracts can be safely used for several months at a time without significant issues.

In some cases, it may not be safe to take horny goat weed. For example, horny goat weed may slow blood clotting, meaning it may worsen bleeding disorders or contribute to an increased risk of bleeding during surgery.

Because horny goat weed acts like estrogen in the body, it may affect estrogen levels and play a role in the development of estrogen-sensitive conditions, such as breast and uterine cancer.

There have also been isolated reports of cardiovascular issues, such as tachyarrhythmia (overly fast heart rate) in people who use horny goat weed supplements.

Because of these safety concerns, it’s important to talk to your healthcare provider before using horny goat weed or any other sexual health supplements.

This conversation is particularly important if you already use prescription medication, or if you’ve been diagnosed with a health condition such as cardiovascular disease.

Horny Goat Weed Interactions

Research suggests that horny goat weed may interact with some medications and supplements, including those that are broken down by the liver.

Horny goat weed may affect how quickly the liver is able to metabolize some medications, such as those targeted by enzymes CYP1A2 and CYP2B6. This could cause these medications to produce different effects and/or side effects.

Because of its effects on blood clotting, horny goat weed may also interact with anticoagulants and antiplatelet medications, contributing to an elevated risk of bleeding and/or bruising.

Some supplements that affect blood clotting, such as ginger, ginkgo, garlic, Panax ginseng and nattokinase, may also be affected by horny goat weed.

Horny goat weed may slow down the absorption and processing of caffeine, causing you to feel the effects of caffeine from coffee, tea, energy drinks or other products for longer or at a greater intensity level. Horny goat weed may also interact with drugs that contain estrogen.

Finally, horny goat weed may interact with medications and supplements that reduce your blood pressure levels, causing a more significant reduction in blood pressure.

To avoid interactions, make sure to inform your healthcare provider about any supplements and medications you currently use or have recently used before taking horny goat weed.

When you search “How long does horny goat weed take to work” or “How fast does horny goat weed work” you’ll see that user reports generally say that horny goat weed has similar effects to some of the prescription medications on the market today.

Responses suggest it starts to work between 30 to 90 minutes after it’s consumed, and may stay in your system between 12 and 36 hours, depending on a variety of factors. But none of these statements have been confirmed by the FDA.

The FDA and similar agencies have not validated any of these claims, and there aren’t any objective studies we’ve found that outline a specific effectiveness timeline — or confirm its effectiveness in the first place.

While research is limited on the effects of horny goat weed, there are a few existing treatments for erectile dysfunction that are backed up by real evidence.

Of these, the most popular are oral PDE5 inhibitors, which work by increasing blood flow to the penis. These come in tablet form and are designed for use around one hour before you plan to have sex (depending on the specific medication), making them a convenient, easy-to-use choice for treating ED.

The four FDA-approved PDE5 inhibitors for ED are:

  • Sildenafil. The active ingredient in Viagra, sildenafil typically works in 30 minutes to an hour and provides relief from ED for up to four hours per dose.

  • Tadalafil. The active ingredient in Cialis, tadalafil is a longer-lasting ED medication that can provide relief from ED symptoms for up to 36 hours per dose.

  • Vardenafil. The active ingredient in Levitra, vardenafil is similar to sildenafil and is used to treat ED for four to five hours per dose.

  • Avanafil. Available as Stendra®, this is a fast-acting ED medication that works in 15 to 30 minutes and is less likely to cause certain side effects.

We offer several FDA-approved ED medications online, following a consultation with a licensed healthcare provider who will determine if a prescription is appropriate.

Other options for treating ED include other medications, medical devices, therapy (when ED is caused by a psychological issue) and lifestyle changes such as keeping yourself active, improving your diet and limiting harmful habits such as smoking and alcohol consumption.

We’ve talked about these techniques more in our detailed guide to the best ways to protect your erections naturally.

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Erectile dysfunction is a frustrating issue that can develop at any time in your life, from your 20s or 30s to older age.

Although there isn’t much evidence that horny goat weed is an effective treatment for ED, there are options available if you find it difficult to get or maintain an erection firm enough to have sex with your partner.

Our guide to the causes of ED goes into more detail about how ED can develop, as well as the steps that you can take to improve your erections and sexual performance.

If you’re worried that you might have ED, you can access effective ED medication online after a consultation with a licensed healthcare provider.

9 Sources

  1. Horny Goat Weed. (2021, August 26). Retrieved from https://medlineplus.gov/druginfo/natural/699.html
  2. 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. BioMed Research International. 841798. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4082836/
  3. Horny Goat Weed. (2015, June 5). Retrieved from https://wa.kaiserpermanente.org/kbase/topic.jhtml?docId=hn-4391000
  4. FDA 101: Dietary Supplements. (2015, July 15). Retrieved from https://www.fda.gov/consumers/consumer-updates/fda-101-dietary-supplements
  5. Dhaliwal, A. & Gupta, M. (2021, June 25). PDE5 Inhibitors. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK549843/
  6. Tan, X. & Weng, W. (1998). Efficacy of epimedium compound pills in the treatment of the aged patients with kidney deficiency syndrome of ischemic cardio-cerebral vascular diseases. Bulletin of Hunan Medical University. 23 (5), 450-2. Retrieved from https://pubmed.ncbi.nlm.nih.gov/10682558/
  7. Zhang, G., Qin, L. & Shi, Y. (2007, July). 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. 22 (7), 1072-9. Retrieved from https://pubmed.ncbi.nlm.nih.gov/17419678/
  8. Punyawudho, B., Puttilerpong, C., Wirotsaengthong, S. & Aramwit, P. (2013). A Randomized, Double-Blind, Placebo-Controlled Crossover Study of Cappra® for the Treatment of Mild or Mild to Moderate Erectile Dysfunction in Thai Male. African Journal of Traditional, Complementary and Alternative Medicines. 10 (2), 310–315. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3746578/
  9. Liu, W. J., Xin, Z. C., Xin, H., Yuan, Y. M., Tian, L., & Guo, Y. L. (2005). Effects of icariin on erectile function and expression of nitric oxide synthase isoforms in castrated rats. Asian journal of andrology, 7(4), 381–388. https://doi.org/10.1111/j.1745-7262.2005.00066.x
Editorial Standards

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references. See a mistake? Let us know at [email protected]!

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Mike Bohl, MD

Dr. Mike Bohl is a licensed physician, a Medical Advisor at Hims & Hers, and the Director of Scientific & Medical Content at a stealth biotech startup, where he is involved in pharmaceutical drug development. Prior to joining Hims & Hers, Dr. Bohl spent several years working in digital health, focusing on patient education. He has also worked in medical journalism for The Dr. Oz Show (receiving recognition for contributions from the National Academy of Television Arts and Sciences when the show won Outstanding Informative Talk Show at the 2016–2017 Daytime Emmy® Awards) and at Sharecare. He is a Medical Expert Board Member at Eat This, Not That! and a Board Member at International Veterinary Outreach.

Dr. Bohl obtained his Bachelor of Arts and Doctor of Medicine from Brown University, his Master of Public Health from Columbia University, and his Master of Liberal Arts in Extension Studies—Journalism from Harvard University. He is currently pursuing a Master of Business Administration and Master of Science in Healthcare Leadership at Cornell University. Dr. Bohl trained in internal medicine with a focus on community health at NYU Langone Health.

Dr. Bohl is Certified in Public Health by the National Board of Public Health Examiners, Medical Writer Certified by the American Medical Writers Association, a certified Editor in the Life Sciences by the Board of Editors in the Life Sciences, a Certified Personal Trainer and Certified Nutrition Coach by the National Academy of Sports Medicine, and a Board Certified Medical Affairs Specialist by the Accreditation Council for Medical Affairs. He has graduate certificates in Digital Storytelling and Marketing Management & Digital Strategy from Harvard Extension School and certificates in Business Law and Corporate Governance from Cornell Law School.

In addition to his written work, Dr. Bohl has experience creating medical segments for radio and producing patient education videos. He has also spent time conducting orthopedic and biomaterial research at Case Western Reserve University and University Hospitals of Cleveland and practicing clinically as a general practitioner on international medical aid projects with Medical Ministry International.

Dr. Bohl lives in Manhattan and enjoys biking, resistance training, sailing, scuba diving, skiing, tennis, and traveling. You can find Dr. Bohl on LinkedIn for more information.

Publications

  • Younesi, M., Knapik, D. M., Cumsky, J., Donmez, B. O., He, P., Islam, A., Learn, G., McClellan, P., Bohl, M., Gillespie, R. J., & Akkus, O. (2017). Effects of PDGF-BB delivery from heparinized collagen sutures on the healing of lacerated chicken flexor tendon in vivo. Acta biomaterialia, 63, 200–209. https://www.sciencedirect.com/science/article/abs/pii/S1742706117305652?via%3Dihub

  • Gebhart, J. J., Weinberg, D. S., Bohl, M. S., & Liu, R. W. (2016). Relationship between pelvic incidence and osteoarthritis of the hip. Bone & joint research, 5(2), 66–72. https://boneandjoint.org.uk/Article/10.1302/2046-3758.52.2000552

  • Gebhart, J. J., Bohl, M. S., Weinberg, D. S., Cooperman, D. R., & Liu, R. W. (2015). Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis. Journal of pediatric orthopedics, 35(6), 565–570. https://journals.lww.com/pedorthopaedics/abstract/2015/09000/pelvic_incidence_and_acetabular_version_in_slipped.5.aspx

  • Islam, A., Bohl, M. S., Tsai, A. G., Younesi, M., Gillespie, R., & Akkus, O. (2015). Biomechanical evaluation of a novel suturing scheme for grafting load-bearing collagen scaffolds for rotator cuff repair. Clinical biomechanics (Bristol, Avon), 30(7), 669–675. https://www.clinbiomech.com/article/S0268-0033(15)00143-6/fulltext

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