St. John's Wort

St. John's wort (Hypericum perforatum) is a yellow-flowered plant with a long history of traditional use. This page is for research only: it describes what has been studied and the safety questions worth checking, rather than promising spiritual or medical results. The U.S. National Center for Complementary and Integrative Health (NCCIH) notes that evidence varies by condition.

What It Is

Known as St. John's wort or hypericum, Hypericum perforatum is a plant with yellow flowers, not a mushroom. It has been used in Greek, Islamic, and Chinese traditional medicine and was historically used for varied concerns, including depression, stomach ulcers, colds, and wound healing. Traditional use records history; it does not by itself establish clinical effectiveness. See the NCCIH overview for the documented background and current evidence.

What Research Shows

Human clinical research has principally evaluated particular oral extracts for depression. Systematic-review evidence suggests that tested extracts may improve symptoms of mild to moderate depression over short study periods and were not significantly different from standard antidepressants in some comparisons. Results varied substantially across trials and preparations, and evidence for severe depression is lacking. The evidence does not establish that St. John's wort is an adaptogen or that it supports immunity, sleep, energy, or general emotional wellbeing. These conclusions come from human trials, not animal or laboratory findings. Read the systematic review of St. John's wort for major depressive disorder and the NCCIH evidence summary for the limits of the research.

Safety and Research Considerations

This research page does not provide a dose or recommend a powder, tea, tincture, capsule, or commercial product. St. John's wort can substantially weaken the effects of many medicines, including hormonal birth control, warfarin, transplant medicines, some HIV medicines, heart medicines, and cancer medicines. Combining it with certain antidepressants or other medicines that affect serotonin can cause serious serotonin-related effects. It can also cause sun sensitivity and other side effects. Pregnancy and breastfeeding warrant particular caution. The FDA warns that St. John's wort can make medicines for HIV/AIDS, heart disease, depression, organ transplantation, and birth control less effective. Anyone considering it should review all medicines and supplements with a health care professional first; dietary supplements are not reviewed by FDA for effectiveness before sale.

Research can help frame questions, but it cannot decide whether a supplement is appropriate for an individual. Depression can be serious and should receive professional assessment. St. John's wort should not replace or delay conventional care, and all supplement and medication use should be disclosed to a health care professional so interactions can be considered.