What It Is Used For
St. John's wort has been used for centuries to treat mental disorders and nerve pain.
In ancient times, herbalists wrote about its use 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 It Is Used
The flowering tops of St. John's wort are used to prepare teas and tablets containing concentrated extracts.
What the Science Says
There is some scientific evidence that St. John's wort is useful for treating mild to moderate depression. However, two large studies, one sponsored by NCCAM, showed 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.
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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 shows that St. John's wort interacts with some drugs. The herb affects the way the body processes or breaks down many drugs; in some cases, it may speed or slow a drug's breakdown.
Drugs that can be affected include:
Indinavir and possibly other drugs used to control HIV infection
Irinotecan and possibly other drugs used to treat cancer
Cyclosporine, which prevents the body from rejecting transplanted organs
Digoxin, which strengthens heart muscle contractions
Warfarin and related anticoagulants
Birth control pills
Antidepressants
When combined with certain antidepressants, St. John's wort may increase side effects such as nausea, anxiety, headache, and confusion.
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.
It is important to inform your health care providers about any herb or dietary supplement you are using, including St. John's wort. This helps to ensure safe and coordinated care.
Sources
National Center for Complementary and Alternative Medicine. St. John's Wort and the Treatment of Depression. National Center for Complementary and Alternative Medicine Web site. Accessed June 30, 2005.
St. John's Wort. Natural Medicines Comprehensive Database Web site. Accessed June 30, 2005.
St. John's wort (Hypericum perforatum L.). Natural Standard Database Web site. Accessed June 30, 2005.
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.
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.
NCCAM, National Institutes of Health
