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Last updated: Mar 17, 2022
5 min read

What is horny goat weed? Does it work?

chimene richa

Medically Reviewed by Chimene Richa, MD

Written by Michael Martin

Disclaimer

If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Horny goat weed is perhaps the most literally named supplement of all time—Chinese farmers noticed that goats seen eating the herb later seemed to be unusually “in the mood.” Enough supplement manufacturers believe in its efficacy that it’s included in dozens of supplements that claim to improve your libido and sexual performance. But does that mean you should be adding horny goat weed pills into your daily repertoire? Let’s look at what the research has to say. 

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What is horny goat weed?

Horny goat weed is a traditional Chinese medicinal herb known as epimedium or yin yang huo. It comes from a flowering shrub native to China and has been used in traditional Chinese medicine to treat fatigue and low libido for thousands of years. 

Today, horny goat weed is most commonly taken as an aphrodisiac. It’s claimed to boost sex drive and improve the quality of erections, among other effects. Horny goat weed is available as a tablet, capsule, tea, or powder, either on its own or as part of other supplement formulations. (It might be listed on a label as Epimedium, Epimedium sagittatum, Epimedium grandiflorum, or Epimedium koreanum). 

What does horny goat weed do?

The active ingredient in horny goat weed is icariin, a compound that’s been studied in animals for a wide range of potential benefits. While we don’t know that it has the same effects in humans, horny goat weed has shown anti-inflammatory and antioxidant effects, as well as heart protection and better erections in animal studies (Fang, 2017; Yang, 2021). 

But does horny goat weed have these effects in humans? Let’s take a look. 

Does horny goat weed work? 

A 2010 study found that icariin seemed to benefit rats who had damaged blood vessels. Those fed an icariin supplement were better able to synthesize nitric oxide in penile tissue (an essential part of getting an erection) than those fed a placebo  (Shindel, 2010).

In another study, researchers found that older rats fed an icariin extract for ten days had more frequent ejaculations and a shorter latency period between ejaculation (Makarova, 2007).

Studies have found that icariin inhibits PDE5—the same mechanism of drugs like Viagra (generic name sildenafil; see Important Safety Information) or Cialis (generic name tadalafil; see Important Safety Information) (though icariin is much less potent than these prescription drugs) (Xin, 2003). 

Unfortunately, these studies on the effects of icariin are mostly suggestive; they’ve been conducted on animals and in test tubes. Horny goat weed may not work the same way in the human body. There haven’t been any studies on horny goat weed’s effect on ED in humans.

Additional horny goat weed benefits

Horny goat weed has also been touted as a potential treatment for the following medical conditions:

Although some studies have been done, the National Institutes of Health (NIH) says that there’s insufficient evidence that horny goat weed is effective for any of the above conditions, including ED. More research is needed (MedlinePlus, 2021).  

Horny goat weed side effects and risks

According to the NIH, horny goat weed is probably safe when taken by mouth in appropriate doses. Side effects such as upset stomach, dry mouth, nosebleeds, dizziness, and rapid heartbeat have been reported (MedlinePlus, 2021). But horny goat weed could have adverse effects when taken with other medications, supplements, or health conditions.

Don’t take horny goat weed if you have a bleeding problem or are scheduled to have surgery; it may affect your blood’s clotting ability. Horny goat weed can also change hormone levels, so you shouldn’t take it if you have a hormone-sensitive cancer (MedlinePlus, 2021).

Don’t take horny goat weed if you’re on certain medications, including (MedlinePlus, 2021): 

  • Estrogens
  • Drugs that lower blood pressure
  • Blood thinners

Let your healthcare provider know about any dietary supplements and medications you’re taking.

References

  1. Anand Ganapathy, A., Hari Priya, V. M., & Kumaran, A. (2021). Medicinal plants as a potential source of phosphodiesterase-5 inhibitors: a review. Journal of Ethnopharmacology, 267, 113536. doi:10.1016/j.jep.2020.113536. Retrieved from https://pubmed.ncbi.nlm.nih.gov/33137431/.
  2. Fang, J. & Zhang, Y. (2017). Icariin, an anti-atherosclerotic drug from Chinese medicinal herb horny goat weed. Frontiers in Pharmacology, 8, 734. doi:10.3389/fphar.2017.00734. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5644024/
  3. Hu, L., Li, L., Zhang, H., et al. (2019). Inhibition of airway remodeling and inflammatory response by Icariin in asthma. BMC Complementary and Alternative Medicine, 19. Retrieved from https://pubmed.ncbi.nlm.nih.gov/31744482/.
  4. Jiang, Z., Hu, B., Wang, J., et al. (2006). Effect of icariin on cyclic GMP levels and on the mRNA expression of cGMP-binding cGMP-specific phosphodiesterase (PDE5) in penile cavernosum. Journal of Huazhong University of Science and Technology. Medical sciences = Hua zhong ke ji da xue xue bao. Yi xue Ying De wen ban = Huazhong keji daxue xuebao. Yixue Yingdewen ban, 26(4), 460–462. doi:10.1007/s11596-006-0421-y. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/17120748
  5. Liu, B., Zhang, H., Xu, C., et al. (2011). Neuroprotective effects of icariin on corticosterone-induced apoptosis in primary cultured rat hippocampal neurons. Brain Research, 1375, 59–67. doi:10.1016/j.brainres.2010.12.053. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/21182828
  6. Makarova, M. N., Pozharitskaya, O. N., Shikov, A. N., et al. (2007). Effect of lipid-based suspension of Epimedium koreanum Nakai extract on sexual behavior in rats. Journal of Ethnopharmacology, 114(3), 412–416. doi:10.1016/j.jep.2007.08.021. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/17890032
  7. MedLine Plus. (2021). Horny goat weed. Retrieved on Mar. 17, 2022 from https://medlineplus.gov/druginfo/natural/699.html
  8. Ning, H., Xin, Z. C., Lin, G., et al. (2006). Effects of icariin on phosphodiesterase-5 activity in vitro and cyclic guanosine monophosphate level in cavernous smooth muscle cells. Urology, 68(6), 1350–1354. doi:10.1016/j.urology.2006.09.031. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/17169663 
  9. Pu, L., Meng, Q., Li, S., et al. (2021). Icariin arrests cell cycle progression and induces cell apoptosis through the mitochondrial pathway in human fibroblast-like synoviocytes. European Journal of Pharmacology, 912, 174585. doi:10.1016/j.ejphar.2021.174585. Retrieved from https://pubmed.ncbi.nlm.nih.gov/34678240/.
  10. Shindel, A. W., Xin, Z. C., Lin, G., et al. (2010). Erectogenic and neurotrophic effects of icariin, a purified extract of horny goat weed (Epimedium spp.) in vitro and in vivo. The Journal of Sexual Medicine, 7(4 Pt 1), 1518–1528. doi:10.1111/j.1743-6109.2009.01699.x. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3551978/
  11. Xin, Z. C., Kim, E. K., Lin, C. S., et al. (2003). Effects of icariin on cGMP-specific PDE5 and cAMP-specific PDE4 activities. Asian Journal of Andrology, 5(1), 15–18. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/12646997
  12. Yan, F. F., Liu, Y., Liu, Y. F., & Zhao, Y. X. (2008). Herba Epimedii water extract elevates estrogen level and improves lipid metabolism in postmenopausal women. Phytotherapy Research: PTR, 22(9), 1224–1228. doi:10.1002/ptr.2451. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/18697183.
  13. Yang, X., Cui, Y., Zhou, et al. (2021). Analysis of pharmacological mechanisms of Yinyanghuo as treatment of erectile dysfunction with network pharmacology-based strategy. Andrologia, 53(2), e13943. doi:10.1111/and.13943. Retrieved from https://pubmed.ncbi.nlm.nih.gov/33368466/.
  14. Zhang, G., Qin, L., & Shi, Y. (2007). 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: the Official Journal of the American Society for Bone and Mineral Research, 22(7), 1072–1079. doi:10.1359/jbmr.070405. Retrieved from https://pubmed.ncbi.nlm.nih.gov/17419678/.