Chapter 45 - St. John’s Wort

Abstract

Hypericum perforatum (St. John’s wort), as juices, extracts, teas, tinctures, oleums, powders, and granules, has been used as oral medication and a vulnerary since recorded history. Hypericum extracts that meet recognized standards are indicated therapeutics for mild to moderate depression. There is peer-reviewed medical literature to support efficacy for this indication. The side effects of Hypericum extracts are generally less than those reported in double-blind studies for nonphytopharmaceuticals. Hypericum oleums are used as vulneraries, and there is evidence they promote uncomplicated cicatrization of wounds. Oleums of hypericum have antimicrobial action. Hypericum extracts upregulate and downregulate gut and hepatic CYP enzymes and xenobiotic transporters, and by these mechanisms they can alter the pharmacokinetics and efficacy of concurrent medications. The dose-limiting side effects are photosensitization and gastrointestinal symptoms.