Horny Goat Weed Uses and Side Effects

By Sarah Malka, MD
Medically reviewed
November 18, 2021

Thanks to its name, horny goat weed stands out from other herbal supplements and pills marketed to boost sexual performance.

And if you spend a little time Googling, you’ll learn it’s used in traditional Chinese medicine (TCM) to treat erectile dysfunction (ED) and other sexual dysfunction. 

Still, just because something is natural doesn’t mean it’s safe—or effective.

And you don’t want to waste your money (or time and energy) trying any remedy that could harm you.

In this article, I’ll explain what horny goat weed is, what it’s used to treat, how it works, and if horny goat weed can make you bigger.

I’ll also discuss the possible side effects of this supplement and when to see a doctor about using natural remedies for sexual dysfunction and other conditions.

What Is Horny Goat Weed?

Horny goat weed is the common name for a species of herb of the Epimedium genus that’s also sometimes referred to as “yin yang huo” in TCM.

According to legend, it earned the name “horny goat weed” when a Chinese goat herder realized his animals were more sexually active after eating the plant’s leaves.

Uses for Horny Goat Weed

Horny goat weed is marketed to treat everything from erectile dysfunction (ED) and sexual problems to menopausal symptoms and weak bones.

However, there’s little scientific evidence to support these claims.

Bone and joint health

Studies have yet to prove if horny goat weed might effectively treat osteoporosis in any specific human population.

A two-year trial of 85 late postmenopausal women found that plant compounds in horny goat weed called phytoestrogen flavonoids may help prevent bone loss.

And one systematic review and meta-analysis from 2017 found that horny goat weed might protect against osteoporosis in rats who had their ovaries removed. But much more human research is necessary.

Erectile dysfunction (ED)

Horny goat weed has long been used in traditional Chinese medicine to treat ED and sexual dysfunction.

Additionally, one study from 2017 found some evidence that it helps increase sexual activity in castrated rats.

But that’s the problem: The majority of research on horny goat weed’s effect on ED has been performed on animals.

There is little to no direct evidence it increases penile blood flow in human males, and no randomized clinical trials have tested the herb’s effect on ED in humans.

Heighten libido

Horny goat weed is also sold as a libido enhancer for women.

However, as with the other clams here, there is no scientific evidence that the herb effectively or safely improves sex drive in women.

How Horny Goat Weed Works

There’s little scientific evidence that horny goat weed works to treat any condition or ailment in humans, or is safe for human use.

In addition, since herbal medicines are not regulated by the FDA, you cannot be sure you are getting the advertised medication or dose, or that there are no harmful ingredients or contaminants in the product.

However, initial research conducted in animals points to two components of the herb that may be beneficial in certain applications: icariin and phytoestrogens.

Icariin is a plant compound some believe has anti-inflammatory, antiosteoporotic, and neuroprotective properties. Icariin may also behave similarly to some ED medications in inhibiting phosphodiesterase type 5 (PDE5) in the treatment of ED.

Phytoestrogens are other plant compounds that may influence estrogen and therefore female sexual desire and bone health.

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Can Horny Goat Weed Make You Bigger?

Though icariin may help to block PDE5 and facilitate better erections, there’s no evidence that horny goat weed, or its active ingredient icariin, can enlarge penis size. 

How to Prepare Horny Goat Weed

Horny goat weed can be found in most drug and health food stores in capsule, powder, tablet, or tea form. 

How much to take

Herbs are not regulated in the U.S., which means there’s no guidance on the appropriate dose for your body or condition and no guarantee that the supplement you buy contains the advertised ingredient or dosage.

When buying horny goat weed, be sure to check the label and follow all recommended instructions.

Possible Side Effects of Horny Goat Weed

Horny goat weed is most likely safe to use short-term and in smaller doses.

But it may be unsafe when used for a long period of time or in high doses.

Serious side effects, including trouble breathing, are possible.

Additionally, horny goat weed may interact with certain medications or supplements and should not be used if you’re taking:

  • Estrogen 
  • Medications broken down by the liver
  • Antihypertensive drugs (for high blood pressure)
  • Anticoagulants or antiplatelets (blood thinners used to slow blood clotting)
  • Caffeine, L-arginine, stinging nettle, niacin, or supplements containing casein peptides
  • Garlic, ginger, ginkgo, nattokinase, or panax ginseng supplements

When to See a Doctor

There’s insufficient evidence to support the use of horny goat weed for any ailment or medical condition.

If you’re interested in alternative or natural therapies for ED, low libido, joint pain, or another condition, contact your doctor or licensed healthcare provider for guidance.

How K Health Can Help

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Frequently Asked Questions

Can horny goat weed replace Viagra for erectile dysfunction?
Though horny goat weed may help to block PDE5, there’s no evidence that it’s as effective (or more effective) than Viagra in the treatment of erectile dysfunction, and no studies prove its safety in humans.
Is horny goat weed an all natural supplement?
Just because horny goat weed is an herbal supplement doesn’t mean what you buy in a store is natural. Herbal supplements are not regulated by the FDA, so check the label for unexpected or added ingredients.
Can you take horny goat weed with other medications?
Horny goat weed can be taken with some other medications. However, the herb may interact with certain medications used for hormone replacement therapy, high blood pressure, and blood clotting. If you’re unsure if it’s safe to add horny goat weed to your health regimen, talk to your doctor.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sarah Malka, MD

Dr. Sarah Malka is a board certified emergency medicine physician with K Health. She completed her residency at Harvard Medical School.