Does St. John's wort work as a treatment for depression?

There has been scientific research to try to answer this question.

In Europe, results from a number of scientific studies have supported the effectiveness of certain St. John's wort extracts for depression. An overview of 23 clinical studies found that the herb might be useful in cases of mild to moderate depression. The studies, which included 1,757 outpatients, reported that St. John's wort was more effective than a placebo (here, a "dummy" pill designed to have no effect) and appeared to produce fewer side effects than some standard antidepressants (Linde et al. British Medical Journal, 1996).

Other studies conducted recently have found no benefit from the use of St. John's wort for certain types of depression. For example, the results of a study funded by Pfizer Inc., a pharmaceutical company, found that St. John's wort, when compared with placebo, was not effective for treating major depression (Shelton et al. JAMA, 2001).

In addition, several components of the National Institutes of Health (NIH)--NCCAM, the Office of Dietary Supplements (ODS), and the National Institute of Mental Health (NIMH)--funded a large, carefully designed research study to find out whether St. John's wort extract benefits people with major depression of moderate severity. This clinical trial (a research study in people) found that St. John's wort was no more effective for treating major depression of moderate severity than placebo (Hypericum Depression Trial Study Group. JAMA, 2002;

Are there any risks to taking St. John's wort for depression?

Yes, there are risks in taking St. John's wort for depression.

Many so-called "natural" substances can have harmful effects--especially if they are taken in too large a quantity or if they interact with something else the person is taking.

Research from NIH has shown that St. John's wort interacts with some drugs--including certain drugs used to control HIV infection (such as indinavir). Other research shows that St. John's wort can interact with chemotherapeutic, or anticancer, drugs (such as irinotecan). The herb may also interact with drugs that help prevent the body from rejecting transplanted organs (such as cyclosporine). Using St. John's wort limits these drugs' effectiveness.

Also, St. John's wort is not a proven therapy for depression. If depression is not adequately treated, it can become severe and, in some cases, may be associated with suicide. Consult a health care practitioner if you or someone you care about may be experiencing depression.

People can experience side effects from taking St. John's wort. The most common side effects include dry mouth, dizziness, diarrhea, nausea, increased sensitivity to sunlight, and fatigue.

What are some other possible problems with using St. John's wort?

Herbal products such as St. John's wort are classified as dietary supplements by the U.S. Food and Drug Administration (FDA), a regulatory agency of the Federal Government. The FDA's requirements for testing and obtaining approval to sell dietary supplements are less strict than its requirements for drugs. Unlike drugs, herbal products can be sold without requiring studies on dosage, safety, or effectiveness. For more information, see the NCCAM fact sheet "What's in the Bottle? An Introduction to Dietary Supplements."