St. John’s wort (Hypericum perforatum) is a plant that has been widely claimed to be an effective natural antidepressant and has thus gained enormous popularity in the United States and Europe. Hypericin, one of many compounds found in the plant, is generally believed to be primarily responsible for the antidepressant action. Several studies of standardized hypericin extracts have found it to be twice as effective as a placebo, and a few European studies have found it somewhat more effective than a standard antidepressant in treating mild to moderate depression. The majority of the studies, however, used small sample sizes, inconsistent classiﬁcation of depression, a wide range of dosages and hypericin concentrations, and only lasted a few weeks. In the absence of research that would establish either long-term effectiveness or long-term safety, the herb has nonetheless become very popular, with annual sales of about $55 million.
With so many people self-medicating, sometimes for major clinical depression, the National Institutes of Health launched a large-scale, multi-site randomized double-blind trial comparing a standardized hypericin extract to both a placebo and the widely prescribed antidepressant Zoloft (a selective serotonin reuptake inhibitor, or SSRI). The rather large sample consisted of 340 people with moderate to moderately severe major depression. The study concluded that St. John’s wort was no more effective in relieving the symptoms of depression than a placebo. Intriguingly, neither was Zoloft on some measures, though it was more effective on others.
Unprocessed Hypericum perforatum (St. John’s wort). Is it an effective antidepressant?
Having examined the effectiveness of St. John’s wort, the National Institute of Mental Health has also recently addressed the herb’s safety. Due to the side effects often associated with pharmaceutical antidepressants, many people are drawn to products such as St. John’s wort in the belief that an herbal supplement will be safer than a drug. These people would do well to read the NIMH “Public Alert on St. John’s Wort.” In it, the agency reports that adverse interactions have been discovered between St. John’s wort and indinavir, a protease inhibitor used to treat HIV-positive patients, as well as cyclosporine, a drug used to prevent organ rejection in transplant patients. So far, the effectiveness of St. John’s wort has not been established for mild depression, but it is clearly unlikely to be effective for major depression, and it can be dangerous in combination with certain other drugs.
- National Center for Complementary and Alternative Medicine. “Study Shows St. John’s Wort Ineffective for Major Depression of Moderate Severity.” www.nccam.nih.gov/news/2002/stjohnswort/pressrelease.htm, 2002;
- National Institute of Mental Health. “Public Alert on St. John’s Wort.” www.nimh.nih.gov/ events/stjohnwort.cfm, 2001.