This fact sheet provides basic information about the herb St. John's wort—common names, uses, potential side effects, and resources for more information. St. John's wort is a plant with yellow flowers whose medicinal uses were first recorded in ancient Greece. The name St. John's wort apparently refers to John the Baptist, as the plant blooms around the time of the feast of St. John the Baptist in late June.
Common Names—St. John's wort, hypericum, Klamath weed, goatweed
Latin Name—Hypericum perforatum
What St. John's Wort Is Used For
- St. John's wort has been used for centuries to treat mental disorders and nerve pain.
- St. John's wort has also been used as a sedative and a treatment for malaria, as well as a balm for wounds, burns, and insect bites.
- Today, St. John's wort is used by some for depression, anxiety, and/or sleep disorders.
How St. John's Wort Is Used
The flowering tops of St. John's wort are used to prepare teas, tablets, and capsules containing concentrated extracts. Liquid extracts and topical preparations are also used.
What the Science Says
- There is scientific evidence that St. John's wort may be useful for short-term treatment of mild to moderate depression. Although some studies have reported benefits for more severe depression, others have not; for example, a large study sponsored by NCCAM found that the herb was no more effective than placebo in treating major depression of moderate severity.
- NCCAM is studying the use of St. John's wort in a wider spectrum of mood disorders, including minor depression.
Side Effects and Cautions
- St. John's wort may cause increased sensitivity to sunlight. Other side effects can include anxiety, dry mouth, dizziness, gastrointestinal symptoms, fatigue, headache, or sexual dysfunction.
- Research has shown that St. John's wort interacts with many medications in ways that can interfere with their intended effects. Examples of medications that can be affected include:
- Birth control pills
- Cyclosporine, which prevents the body from rejecting transplanted organs
- Digoxin, a heart medication
- Indinavir and possibly other drugs used to control HIV infection
- Irinotecan and possibly other drugs used to treat cancer
- Seizure-control drugs, such as dilantin and phenobarbital
- Warfarin and related anticoagulants.
- Taking St. John's wort with certain antidepressants may lead to increased serotonin-related side effects, which may be potentially serious.
- St. John's wort is not a proven therapy for depression. If depression is not adequately treated, it can become severe. Anyone who may have depression should see a health care provider. There are effective proven therapies available.
- Tell all your health care providers about any complementary and alternative practices you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care. For tips about talking with your health care providers about CAM, see NCCAM'sTime to Talk campaign.
- De Smet PA. Herbal remedies. New England Journal of Medicine. 2002;347(25):2046–2056.
- Hypericum Depression Trial Study Group. Effect of Hypericum perforatum (St. John's wort) in major depressive disorder: a randomized controlled trial. Journal of the American Medical Association. 2002;287(14):1807–1814.
- National Center for Complementary and Alternative Medicine. St. John's Wort and Depression.National Center for Complementary and Alternative Medicine Web site. Accessed atnccam.nih.gov/health/stjohnswort/sjw-and-depression.htm on June 3, 2010.
- St. John's wort. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on February 15, 2010.
- St. John's wort. In: Blumenthal M, Goldberg A, Brinckman J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Lippincott Williams & Wilkins; 2000:359–366.
- St. John's wort (Hypericum perforatum L.). Natural Standard Database Web site. Accessed at www.naturalstandard.com on February 15, 2010.