Related topics: •  Mental Health & Depression

St. John's wort (Hypericum perforatum ) is a yellow-flowered herb native to Europe that has been used for centuries to treat anxiety , insomnia, and depression. It gets its name from the red oil it exudes when you pinch its leaves -- early Christians thought it represented the blood of St. John the Baptist's beheading. "Wort" is Old English for plant.

Studies suggest that St. John's wort may be effective for treating mild depression, but not for more severe depression. A review of 23 German studies concluded that St. John's wort was as effective as the standard drugs for mild to moderate depression. However, a study reported in the Journal of the American Medical Association (JAMA) questions those results, citing the poor design of the original German studies. The JAMA study also found that when St. John's wort was compared to a placebo, or dummy pill, it was ineffective in treating moderate to severe depression in 200 test subjects. More recently, a study with 340 participants by the National Center for Complementary and Alternative Medicine, the Office of Dietary Supplements and the National Institute of Mental Health found that St. John's wort was no more effective than a placebo in treating major depression of moderate severity.

So far, however, a few studies have indicated that St. John's wort may help with depression-related insomnia and seasonal affective disorder (the winter blues).

Because it produces some of the same side effects as prescription antidepressants such as Prozac, researchers assume that St. John's wort too works by slowing the breakdown of the brain chemical serotonin. (Low levels of serotonin are thought to be associated with depression.) Experiments with rats suggest that the herb may create more receptors on brain cells to capture serotonin and make it stick around longer. As with Prozac, most people need to take it for four to six weeks before they notice a difference.

In most studies, only about 20 percent of patients who took St. John's wort complained of side effects (compared to an average of 53 percent with other antidepressants). The most common ones are dry mouth, upset stomach, and dizziness.

Don't use St. John's wort if you are already taking other antidepressants. This mix can lead to serotonin overdose syndrome, which can be fatal in severe cases; early symptoms include sweating, stomach problems, and insomnia.

Also, check with your doctor before using this herb if you are taking ANY prescription medicine. A recent study at the Medical University of South Carolina found that St. John's may interfere with your body’s absorption of drugs used to treat high blood pressure, high cholesterol, anxiety, and up to 50 percent of all drugs currently prescribed by physicians.

The FDA also cautions against using St. John's wort if you're currently taking HIV drugs or if you've had an organ transplant. A National Institutes of Health study showed that the herb significantly lowered amounts of the antiviral drug indinavir in eight men with HIV, while a Swiss study found that St. John's wort strongly interfered with the effectiveness of immune drugs in two heart transplant patients.

A study of five cancer patients released at the American Association for Cancer Research's conference in San Francisco found that St. John's wort interfered with the anti-cancer drug irinotecan (Camptosar) -- even three weeks after patients stopped taking the herb.

Women who take oral contraceptives should be cautious about taking St. John's wort -- two small studies found that taking the herb with oral contraceptives caused breakthrough bleeding and increased risk of pregnancy in some women.

Herbs and their extracts can be potent drugs, so don't take them lightly. If you suspect that you are suffering from depression, see a doctor or therapist first for a diagnosis and more information on appropriate treatment options.

St. John's wort is available in capsule form, tea, or tincture from health food stores or pharmacies, but keep in mind that the government doesn't regulate herbal remedies, so it's hard to know exactly what you're getting. In rare cases products may be contaminated with undesirable substances. Your best bet may be capsules that contain hypericin, the active compound used in many of the studies, but surveys have shown that even capsules can vary significantly in potency from one quarter to twice the labeled dose. Teas and tinctures do not provide a reliable dose.

Further Resources

Varro E. Tyler, PhD. Herbs of Choice: The Therapeutic Use of Phytomedicinals. Pharmaceutical Products Press, 1994.

Andrew Weil, M.D. Natural Health, Natural Medicine. Houghton Mifflin, 1995, 1998.

References

Last updated January 15, 2009
Copyright © 1998 Consumer Health Interactive and OneBody, Inc.

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