By Hong Mautz
Jan. 11 (CBSHealthWatch)--The herbal supplement St. John's wort (Hypericum perforatum) has been widely used to treat depression. But a new study that has reviewed all existing studies on the herb still leaves many questions unanswered about its safety and effectiveness.
"We still have no studies to show whether St. John's wort can have sustained benefits in reducing the risk for depression recurrences over the longer haul," says senior author of the study, P. Murali Doraiswamy, MD, director of psychiatry clinical trials at Duke University in Durham, North Carolina.
Philip Muskin, MD, chair of the scientific program committee at the American Psychiatric Association, says that the findings are not surprising and that there are many things yet to be understood about this herb.
"We don't know what the lethal dose is," he says. "In addition, there is no rigid standard on how to prepare these products."
"There are questions about how the herb works, and even which part of the plant should be used," says Muskin, who is also a professor of clinical psychiatry at Columbia University, College of Physicians and Surgeons in New York City. "We have a lot of data on St. John's wort, but they are not the kind of robust data" that you would rely upon when treating someone with depression, he says.
"Our review lists the growing list of drugs that could potentially interact with the herb," says Doraiswamy. "We are just scratching the tip of the iceberg as far as herbal-drug interactions are concerned. Certain side effects also become more apparent only after long-term use or if systematically solicited."
St. John's wort may interact with tetracycline (Sumycin), cyclosporin (Sandimmune, Neoral), protease inhibitors, digoxin (Lanoxin), warfarin (Coumadin), and some oral birth control medications, according to researchers. There is some evidence that St. John's wort may cause certain liver enzymes to process those types of medications faster than usual, resulting in less effective doses of those drugs in the body.
Muskin points out that physicians are reluctant to recommend the use of St. John's wort to patients because information on reliable brands of the herb is sketchy. "I can get a reliable brand of Prozac, 100% of the time," he says. "But is the brand of St. John's wort going to be anything, or is it going to be nice pills containing nothing? It's a real concern."
Researchers point out that it is misleading to believe that natural is safer. Just because something is an herb does not mean that it is automatically devoid of side effects or drug interactions. People should not self-medicate, and should discuss their use of the herb with their doctors, researchers say.
There is a lot that is valuable in complimentary and alternative medicine, if people want to use it, they should tell their physicians, according to Muskin. "An open-minded approach from both physicians and patients is really what gets people better."
The findings appear in the January 2001 issue of Public Health Nutrition.
© 2001 by Medscape