Information About St. John's wort.

St. John's wort (Hypericum perforatum) is a plant with yellow flowers that commonly grows in the wild. It has been used for centuries in many folk and herbal remedies for diverse illnesses. In the United States today, St. John's wort extract is sold in health food stores, pharmacies, and grocery chains as a nutritional supplement. It is promoted as a "natural" way to improve mood, and as a treatment for mild to moderate depression. However, questions remain about whether or not St. John's wort really does what its marketers claim. It is important for anyone taking St. John's wort or considering its use to talk to a physician.

Is St. John's wort safe?

Because St. John's wort is developed and marketed as a nutritional supplement and not as a drug, the U.S. Food and Drug Administration (FDA) does not regulate its production. Hence, consumers cannot be certain that the ingredients in any given brand of St. John's wort are pure, nor can they be sure of the dosage they are taking or the possible side effects. Different brands of St. John's wort have been found to contain different amounts of the extract.

As with many other herbal or natural supplements, there is limited scientific data on the safety of St. John's wort. Some people may feel it is safer to take St. John's wort than a chemically-manufactured antidepressant medication because it is "natural." Yet St. John's wort and other natural supplements can act on the body just as medications do, and they may have unexpected side effects.

In fact, a recent NIH study found that St. John's wort adversely interacts with an antiviral medication for HIV infection called indinavir. A separate study by Swiss physicians described two cases of interaction between St. John's wort and cyclosporine, a drug used to prevent rejection of organ transplants. This and other research suggests that St. John's wort also may interfere with the effectiveness of birth control pills and medications for heart disease, depression,' seizures, and certain cancers. The FDA issued a Public Health Advisory on February 10, 2000, warning physicians of these potential adverse interactions and advising them to alert their patients. For details on these findings, visit http://www.nimh.nih.gov/events/stjohnwort.cfm.

Is St. John's wort effective for depression?

At present, the answer to this question remains unclear. While studies conducted in Europe indicate St. John's wort can relieve depression, these studies had several limitations. For example, the doses and brands of extract varied; criteria for accepting research patients differed; and the trials were too brief to conclude that St. John's wort is better than a placebo, or to determine the effects of extended use or the risk of relapse. These limitations led the U.S. government's National Institutes of Health (NIH) to design a study addressing each concern.

The Treatment of Major Depression with St. John's Wort (Hypericum) study, sponsored by the National Institute of Mental Health, the National Center for Complementary and Alternative Medicine, and the Office of Dietary Supplements, is the first controlled, large-scale, and long-term clinical trial of St. John's wort for major depression. Recruitment of participants for this three-year study is now closed, and the results are expected in 2001. The findings will be announced on the NIMH web site http://www.nimh.nih.gov. Details on the study's design can be found in the National Library of Medicine's clinical trials database http://www.clinicaltrials.gov.

Researchers are not yet certain which components of St. John's wort are active. Some evidence suggests that the component hyperforin may have effects on mood. The plant also contains polycyclic phenols, hypericin, and pseudohypericin, in addition to flavonoids (hyperoside, quercetin, isoquercitrin, rutin), kaempferol, luteolin, and biapigenin.

Should It Be Used?

For people with depression seeking help now, NIH recommends the use of proven treatments, which are successful in up to 80 percent of patients. These treatments include FDA-approved antidepressant medications, certain forms of psychotherapy, or both.

There is evidence that some people with bipolar disorder (manic-depressive illness) who take St. John's wort may experience a switch into mania, especially if they are not on any mood-stabilizing medication (e.g., lithium, valproate). Therefore, before taking St. John's wort, it is important to discuss its use with a physician.

For More Information

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All material in this fact sheet is in the public domain and may be copied or reproduced without permission from the Institute. Citation of the source is appreciated.

February 2001

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This page was last updated: March 9, 2001