Goat weed is conventionally known as Horny Goat Weed. That’s what it will be called right on the bottle in your local pharmacy or health food store. Its history dates back hundreds of years to China, when a shepherd noticed his goats were a little more sexually rambunctious than usual after eating this plant. The Chinese call it Yin Yang Huo, which loosely means “licentious goat plant.” It was adopted for medicinal purposes as an herbal remedy to treat joint, liver, kidney and back disorders, as well as an aphrodisiac. Scientific tests have shown that it does, indeed, work as an aphrodisiac.

Side Effects

There have not been many studies on the active ingredients of goat weed, but two noted side effects of taking goat weed in pill form and larger-than-recommended doses have been increased heart rate and insomnia or light sleep. However, these symptoms have been noted only when goat weed was taken in high doses. The insomnia effect has been noted in studies even when the high doses were taken in the morning. No other deleterious side effects have been chronicled in medical testing thus far. Some physicians recommend that goat weed extract not be taken by pregnant or lactating women, though no specific dangers have been identified.

How Goat Weed Works

Goat weed contains flavonoids, sterols and magnaflorine that may influence sexual biochemistry in a variety of ways. It is thought that the biochemical reactions enhance neurotransmitters in the brain that play a role in arousal and emotional response. The goat weed seems to inhibit an enzyme that stops or slows the production of these neurotransmitters.

Layman’s Glossary

Most flavonoids function in the human body as antioxidants and prevent damage to cells. A sterol is a steroid with an alcohol group attached to it. Magnaflorine increases relaxation of smooth muscles and increases blood circulation to things like the penis and clitoris. Put together, you have a steroid, an antioxidant that protects the cells, increases testosterone levels and interrupts the neurotransmitters that dampen sexual arousal, and you have an aphrodisiac. The plant blocks the same erection-inhibiting enzyme (phosphodiesterase-5) as Viagra.

Long-Term Side Effects

No long-term side effects have been established because testing has not yet been done over sufficient periods of time. In China, where goat weed has been used for centuries, no long-term side effects have reported. A drug called Compound 5, based on a derivative of goat weed, is currently in clinical trials, though it is not expected to hit the marketplace for another decade or so (see Resources).


Since goat weed comes in pill form with recommended dosage amounts written on the bottle, so follow the directions. Don’t overdo dosages with the expectation that results will be immediate. It usually takes four to five days of taking goat weed before experiencing the desired effects. If side effects do develop, consult a physician or pharmacist before continuing using the pills.