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What are the side effects of St. John’s wort?

St. John’s wort is an herbal remedy that comes from the plant, Hypericum perforatum. There are at least ten active compounds in St. John’s wort.

Most people tolerate St. John's wort without problems. The most commonly reported side effects of St John’s wort are nausea and sun sensitivity. Fair-skinned people should use a sunscreen with a SPF of 15 or higher while spending long periods in the sun. Less common side effects are dry mouth, itching and rash, fatigue, and restlessness. Pregnant women should not take St. John’s wort.

Sources:
Gaster, B., Holroyd, J. “St. John’s wort for depression: a systematic review,” Archives of Internal Medicine 24 (2000).
The Review of Natural Products. Facts & Comparisons, 2007.
Robbers, J.E., V.E. Tyler. Tyler’s Herbs of Choice: The Therapeutic Use of Phytomedicinals. The Haworth Press, 1999.
Philipp, M. "Hypericum Extract versus Imipramine or Placebo in Patients With Moderate Depression: Randomised Multicentre Study of Treatment for Eight Weeks," British Medical Journal 319 (1999).
Woelk, H. "Comparison of St John's Wort and Imipramine for Treating Depression: Randomised Controlled Trial," British Medical Journal 321 (2000).
Schrader, E. " Equivalence of St John's Wort Extract (Ze 117) and Fluoxetine: A Randomized, Controlled Study in Mild-moderate Depression," International Clinical Psychopharmacology 15 (2000).
Micromedex® Healthcare Series. Thomson Micromedex, 2007.