Epimedium is better known by its amusing nickname, “horny goat weed.” Dozens of popular sexual enhancement products use some amount of the herb, and if you’ve ever wondered whether or not it’s effective, you’re certainly not alone.

Horny goat weed, alternatively known as barrenwort, bishop’s hat, or epimedium, is a genus of flowering plants with a long history of use in Traditional Chinese Medicine, where it’s referred to as yin yang huo. According to a popular legend, the herb’s aphrodisiac qualities were discovered accidentally by a Chinese goatherd who began to notice more vigorous sexual activity among his flock after they consumed the plant.

Records dating back as far as 300 BCE mention the plant as a “body-building agent,” and over the ensuing centuries, the herb has been used to treat a laundry list of conditions including menopause, joint pain, and even osteoporosis. Recently, it’s been marketed as a way to improve the immune system and to prevent inflammation.

However, epimedium is most popular as an aphrodisiac and as a supplement for sexual dysfunctions. While horny goat weed is occasionally available in its raw form, it’s typically sold as an extract in tablets or capsules.

So Does It Work?

While there’s not enough clinical evidence to say whether epimedium enhances sexual desire or treat erectile dysfunction in humans, the anecdotal evidence seems to be overwhelmingly positive.

Some promising results have been achieved in laboratory studies, including a 2006 report that icariin, the primary active constituent in the plant increased levels of nitric oxide and inhibited the enzyme PDE-5 (the same enzyme that Viagra acts upon), contributing to the relaxation of penile tissue and subsequent penile blood flow increase in rabbits. Another 2006 study demonstrated icariin’s effectiveness in increasing penile blood pressure in rats, potentially indicating that epimedium could serve as a treatment for erectile dysfunction.

A host of other studies performed throughout the course of 2007 and 2008 more reliably indicate that icariin does stimulate activity in bone tissue, enhancing productivity during bone formation and helping to guard against deterioration of bone that occurs as a result of osteoporosis.

However, no studies have been performed that support or refute any of the other purported benefits of horny goat weed, and it’s possible that some of the sexual enhancement benefits come through the placebo effect. It’s also important to note that epimedium needs clinical testing before it’s marketed as an actual treatment for low bone density, erectile dysfunction, or anything else – scientists need to see how much horny goat weed a person would need in order to see real results. They would also need to prove that pills, lubes, and other products can effectively deliver the active substances.

Side Effects and Other Risks

Because of its relative lack of clinical testing and its status as an herbal supplement (meaning its sale isn’t regulated by the FDA), it’s a good idea to approach horny goat weed with caution. Most people who use horny goat weed see no significant side effects, but some users report upset stomach, dizziness, dry mouth, and other issues. There’s some evidence that epimedium could affect blood pressure, so people with medical conditions should speak with their physicians before using it.

If you’re fairly healthy and you’re looking for a simple way to improve your libido, horny goat weed could be a fun enhancement supplement. Take a small amount at first to limit your chances of side effects. Lubricants with the plant might be effective, too – again, there’s no clinical studies, so it’s tough to say.

However, remember this: while epimedium might have an effect on sexual function, it’s not a replacement for qualified treatment from a medical condition. If you have erectile dysfunction, fatigue, a diminished libido, or any other serious symptom, you should talk to your physician before taking supplements or sexual enhancement products.