|Section:||Hypericum sect. Hypericum|
Hypericum perforatum, known as perforate St John's-wort, common Saint John's wort and simply St John's wort, is a flowering plant in the family Hypericaceae. St. John's wort has been used in alternative medicine as a likely effective aid in treating mild to moderate depression and related symptoms such as anxiety or insomnia. Study results on the effectiveness of Hypericum perforatum for depression have been mixed. Since it causes drug interactions, it might not be an appropriate choice for many people, particularly those who take other medications. The primary phytochemical constituents of St John's wort are hyperforin and hypericin. Hypericum perforatum is native to parts of Europe, Asia, and northern Africa, but has spread and is considered an invasive species in some parts of the world. The plant is poisonous to livestock.