Horny goat weed is a traditional Chinese medicinal herb, commonly referred to as yin yang huo. As a form of alternative medicine, the herb has been used to treat conditions from hay fever, nerve pain fatigue, osteoporosis and erectile dysfunction, as well as an anti-cancer ally, to restore circulation, aphrodisiac, anti-oxidant, to increase testosterone and estrogen levels. One of the most well known and oldest herbs for sexual health dating back over 2000 years. The story behind this infamous herb is that a goat herder in China noticed some peculiar behaviour in his flock after feeding on a particular patch of flowering plants - thus for the past 2000 years it has been known in herbal supplement guides as horny goat weed.