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Jan 22, 2021
6 min read

Horny goat weed side effects: what to expect

Horny goat weed is an herb often marketed as a sexual enhancement product, claimed to improve erections and sexual desire. It contains icariin, a natural substance that may have effects mildly similar to Viagra or Cialis. But horny goat weed can have side effects and can be dangerous when taken if you have certain medical conditions or are taking certain other medications or supplements. Consult your healthcare provider before beginning any new supplement.

steve silvestro

Reviewed by Steve Silvestro, 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.

It seems like everywhere you look, you see another supplement or herb or “magical” substance being promoted as a solution for male virility. Horny goat weed is one herb that’s been used for centuries for just this purpose. But does it really work? And what are the most common horny goat weed side effects? 

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What is horny goat weed (barrenwort)?

Horny goat weed is a traditional Chinese medicinal herb also known as epimedium, barrenwort, or yin yang huo. Derived from a flowering shrub native to China, it has been used in traditional Chinese medicine for thousands of years to treat fatigue and low libido, among other conditions. Its name comes from an old wives’ tale that goats seen eating the herb seemed particularly hot to trot (Corazza, 2014).

Today, many people take horny goat weed as an aphrodisiac or libido enhancer. It is alleged to boost sex drive, sexual performance, and quality of erections. However, there are no clinical trials in humans on these effects (Corazza, 2014). 

Horny goat weed is available as a tablet, capsule, tea, or powder. It is sold as a supplement on its own or as part of other supplement formulations. It might be listed on a label as Barrenwort, Epimedium, Epimedium koreanum, Epimedium sagittatum, Epimedium grandiflorum or yin yang huo.

Most common horny goat side effects

According to the National Institutes of Health (NIH), horny goat weed is “possibly safe” when taken in appropriate doses. Since there isn’t much research on horny goat weed, an appropriate range of dosing hasn’t been determined (MedLinePlus, 2020). 

At commonly used doses, it can cause side effects, including (MedLinePlus, 2020): 

  • Upset stomach
  • Dry mouth
  • Nosebleeds
  • Dizziness
  • Rapid heartbeat.

More severe problems, such as breathing difficulties and liver toxicity, have also been reported. 

Horny goat weed warnings

Horny goat weed can be dangerous if taken when you have certain health conditions or in conjunction with other medications. For example (MedLinePlus, 2020):

  • You shouldn’t take horny goat weed if you have heart disease. The supplement has been reported to cause rapid or irregular heartbeat. 
  • Horny goat weed might also lower blood pressure and cause fainting. This can be problematic if you already have low blood pressure.
  • Horny goat weed contains phytoestrogens, natural chemicals that act somewhat like estrogen.  You shouldn’t take horny goat weed if you have hormone-sensitive cancer.
  • Horny goat weed may slow blood clotting, so don’t take it if you have a clotting disorder. 

If you are scheduled for surgery and take horny goat weed, speak with your healthcare provider. You may need to stop taking horny goat weed at least two weeks before surgery to prevent excessive bleeding from the procedure.


Horny goat weed drug interactions

Horny goat weed could have adverse effects when taken with other medications or supplements.

Don’t take horny goat weed if you’re on certain medications, including steroids (like cortisone, prednisone, prednisolone, and methylprednisolone), aromatase inhibitors (like anastrozole, exemestane, and letrozole), blood thinners, and nitroglycerin (MedLinePlus, 2020).

Horny goat weed can also interact with aspirin, birth control pills, antidepressants, and medications for high blood pressure, high cholesterol, thyroid issues, and immune disorders (MedLinePlus, 2020). 

Because of all the possible side effects and interactions with other medications and supplements, it’s a good idea to talk with your healthcare provider before you start taking herbal supplements of any kind.

What does horny goat weed do?

During an erection, a natural compound known as nitric oxide helps blood vessels relax, allowing blood to flow into the penis. In cases of erectile dysfunction (ED), a protein called phosphodiesterase type 5 (PDE5) can interfere with that process, making it more challenging to get and maintain an erection.

Horny goat weed contains icariin, a natural chemical that is a mild inhibitor of PDE5 (Xin, 2003; Jiang, 2006; Ning, 2006). Inhibiting PDE5 is how ED medications like sildenafil (brand name Viagra) and tadalafil (brand name Cialis) work.

In a 2007 study, researchers found that older rats fed an icariin extract for 10 days had more frequent ejaculations and a shorter latency period between ejaculation (Makarova, 2007).

But studies on horny goat weed and icariin are largely suggestive, having been conducted on animals and in test tubes. Horny goat weed may not work the same way in the human body. There have been no clinical trials on horny goat weed’s effect on ED in humans.

Horny goat weed for women

Horny goat weed is believed to act similarly to estrogen. A 2008 study found that postmenopausal women who took horny goat weed extract for six months had lower cholesterol and higher estrogen levels than those who didn’t (Yan, 2008).

A 2017 study found that icariin lowered the risk of osteoporosis in female rats whose ovaries had been removed. The animals treated with icariin had “significantly higher” bone mineral density and lower bone mineral turnover than rats that didn’t consume the supplement. Researchers called for larger clinical trials to see if their findings could indicate a useful treatment for postmenopausal women (Liu, 2017).

Better ways to treat ED

Erectile dysfunction (ED) happens when you can’t get an erection that’s firm enough to have satisfying sex. That could mean erections that don’t last as long, are softer than you’d like, or are less frequent than ideal. Most men experience ED at some point in their lives. By age 50, about half of men will.

But that doesn’t mean ED is something to ignore if it happens to you. In some cases, erectile dysfunction can be caused by a serious health condition, including heart disease, diabetes, high blood pressure, or mental health issues like depression (Nunes, 2012; ADA, n.d.; Rajkumar, 2015). It’s wise to talk to a healthcare provider at the first sign of ED, even if you’re young and otherwise healthy.

Many treatment options are available for ED, including oral prescription medications such as sildenafil (brand name Viagra), tadalafil (brand name Cialis), and vardenafil (brand names Levitra and Staxyn). Oral medications are highly effective for most men.

Other treatment options include medications that are injected into the penis (including alprostadil, BiMix, and TriMix), surgery to correct conditions that might be causing ED (such as Peyronie’s disease), devices that can help blood flow into and remain in the penis (such as cock rings and penis pumps), and mental health counseling.

Read everything you need to know about options to treat ED here.

References

  1. Corazza, O., Martinotti, G., Santacroce, R., Chillemi, E., Di Giannantonio, M., Schifano, F., & Cellek, S. (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, 2014, 841798. doi: 10.1155/2014/841798. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4082836/
  2. Horny Goat Weed: MedlinePlus Supplements. (2020). Retrieved on Jan 12, 2020 from https://medlineplus.gov/druginfo/natural/699.html#Safety
  3. Jiang, Z., Hu, B., Wang, J., Tang, Q., Tan, Y., Xiang, J., & Liu, J. (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. Retrieved from https://link.springer.com/article/10.1007%2Fs11596-006-0421-y
  4. Liu, Y., Zuo, H., Liu, X., Xiong, J., & Pei, X. (2017). The antiosteoporosis effect of icariin in ovariectomized rats: a systematic review and meta-analysis. Cellular and molecular biology (Noisy-le-Grand, France), 63(11), 124–131. doi: 10.14715/cmb/2017.63.11.22. Retrieved from https://www.cellmolbiol.org/index.php/CMB/article/view/1643
  5. Makarova, M. N., Pozharitskaya, O. N., Shikov, A. N., Tesakova, S. V., Makarov, V. G., & Tikhonov, V. P. (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://linkinghub.elsevier.com/retrieve/pii/S0378874107004266
  6. Ning, H., Xin, Z. C., Lin, G., Banie, L., Lue, T. F., & Lin, C. S. (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.goldjournal.net/article/S0090-4295(06)02155-8/fulltext
  7. Nunes, K. P., Labazi, H., & Webb, R. C. (2012). New insights into hypertension-associated erectile dysfunction. Current Opinion in Nephrology and Hypertension, 21(2), 163–170. doi: 10.1097/mnh.0b013e32835021bd. Retrieved from https://pubmed.ncbi.nlm.nih.gov/22240443/
  8. Rajkumar, R. P., & Kumaran, A. K. (2015). Depression and anxiety in men with sexual dysfunction: a retrospective study. Comprehensive psychiatry, 60, 114–118. doi: 10.1016/j.comppsych.2015.03.001. Retrieved from https://www.sciencedirect.com/science/article/abs/pii/S0010440X15000346?via%3Dihub
  9. Xin, Z. C., Kim, E. K., Lin, C. S., Liu, W. J., Tian, L., Yuan, Y. M., & Fu, J. (2003). Effects of icariin on cGMP-specific PDE5 and cAMP-specific PDE4 activities. Asian journal of andrology, 5(1), 15–18. Retrieved from https://pubmed.ncbi.nlm.nih.gov/12646997/
  10. Yan, F.-F., Liu, Y., Liu, Y.-F., & Zhao, Y.-X. (2008, September). Herba Epimedii water extract elevates estrogen level and improves lipid metabolism in postmenopausal women. doi: 10.1002/ptr.2451. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/18697183