Also known asHypericum perforatum, Perforated bush, Hypericum, and Klamath weed.IntroductionHepericum perforatum is one of many species known commonly as St John’s Wort, and is the species most commonly associated with herbal medicine. It is native to Europe but has since been naturalized to other temperate climates around the world, with particular prominence in North America. The plant is a creeping perennial, producing star-shaped yellow flowers containing long, abundant stamens. St John’s Wort is traditionally harvested near the beginning of the flowering cycle on St John’s Day, which falls annually on June 24th. The flowers continue blooming throughout the summer and may be freely harvested throughout the season.Considered a holy herb, St John’s Wort was employed for a number of folkloric uses during the Middle Ages. It was once believed that the herb helped to protect people from curses, demons, and lightning.In contrast to its many uses, some countries have identified St John’s Wort as an invasive species and noxious weed. Though useful to humans, it can be dangerous to livestock, sprouting up in pastures and causing photosensitivity to the grazing animals that feed upon it. Ingestion of the plant may lead to health complications and even death.ConstituentsHypericin and related compounds, rutin, bitters, and tannins.Parts UsedThe dried flowering tops and leaf.Typical PreparationsTraditionally used as a tea, sometimes available in tea bags; also used to make a red St. John’s oil for use in liniments and lotions, but only from fresh material. May also be administered as a capsule or extract for convenience.SummarySt John’s Wort is traditionally used to support healthy mood and promote emotional well-being. Numerous clinical trials have studied the efficacy of St John’s Wort in this capacity, with most of them showing positive results that are comparable to conventional treatments.PrecautionsSt. John’s wort extracts may increase sensitivity to sunlight and risk of sunburn, but this is extremely rare when the whole herb is used. Not to be used with a MAO or Protease inhibitor.For educational purposes only This information has not been evaluated by the Food and Drug Administration.This information is not intended to diagnose, treat, cure, or prevent any disease.