St. John's Wort

St. John's wort (Hypericum perforatum) is an over-the-counter herbal supplement used for its antidepressant, anti-inflammatory, and wound-healing properties. Although it has been prescribed in Europe for mild to moderate depression, negative clinical trials and multiple reports of adverse drug interactions have raised concern about its use. St. John's wort induces various P450 isozymes (CYP 1A2, 2C19, 2C9, and 3A4) and P-glycoprotein systems. Drug interactions with the herbal product can lead to treatment failures with many medications, including hormonal contraceptives, antiretrovirals, immunosuppressive agents, narcotics, anticoagulants, and antifungals. There is also a risk for serotonin syndrome when St. John's wort is used in combination with other serotonergic antidepressants. The lack of strict regulation of herbal products that results in variable quality and content (unknown toxic ingredients or inactive ingredients) is also a concern.