Icariin is a chemical compound classified as a prenylated flavonol glycoside, a type of flavonoid.

It is the 8-prenyl derivative of kaempferol 3,7-O-diglucoside.

The compound has been isolated from several species of plant belonging to the genus Epimedium which are commonly known as horny goat weed, Yin Yang Huo,[1] and Herba epimedii.

[2] Extracts from these plants produce aphrodisiac effects, and are used in traditional Chinese medicine to enhance erectile function.

[3] However, clinical trial data are lacking to support these claims.