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St. John's Wort


Since ABC's 20/20 segment on St. John's wort, I have been inundated by questions concerning the effectiveness of this herb. I was very skeptical at first but after researching the topic, I feel it may have some merit. St. John's wort comes from a yellow flowering plant that is common in Europe as well as the United States. St. John's wort is used eight to one over standard antidepressants in Germany. In Germany, physicians prescribed over 66 million daily doses of St. John's wort in 1994.


This plant has been used for over 2000 years to treat numerous different ailments including depression, anxiety and insomnia. It is sold over-the-counter in Germany as well as the United States. St. John's wort is named after John the Baptist presumably because his birthday falls around the same time of year that the flower blooms.


Hypericin is the component of St. John's wort, which is thought to be the active ingredient. There are numerous other chemical compounds that can be found in St. John's wort. An MAO inhibitor is a substance that prevents an enzyme in the brain from working properly that results in a lower level of neurotransmitters (messengers) in the brain. MAO inhibitor stands for monoamine oxidase inhibitor. One of the ingredients of St. John's wort is a MAO inhibitor, but it is in small amounts and of no medical significance. Nevertheless, St. John's wort was mistakenly classified as a MAO inhibitor in the past. The significance is that MAO inhibitors have several drug interactions that may cause dangerously high blood pressure readings and this limits its usefulness.

Hypericin is felt to act by inhibiting the uptake of the neurotransmitters serotonin, norepinephrine and dopamine. The plasma half-life of hypericin is about 25 hours meaning that it takes about 25 hours for half of the substance to be eliminated from the blood stream.

Clinical Studies

There have been several dozen studies looking at the effectiveness of St. John's wort. The British Medical Journal recently conducted a study of 23 randomized trials involving over 1,700 patients. The patients had mild to moderate depression. St. John's wort was just as effective as standard antidepressants. However, none of the studies exceeded 12 weeks in duration making them less than ideal. Fifty percent of patients taking St. John's wort improved with respect to their depression as opposed to only 23 percent of patients that were taking placebo. In several studies, St. John's wort was more effective than standard antidepressants for mild to moderate depression. To my knowledge, there are no studies proving the effectiveness of St. John's wort in severe depression or manic-depressive illness. I would not recommend starting with St. John's wort in patients with severe depression until St. John's wort has been proven to be as effective as standard antidepressants.

Side Effects

One of the main advantages of St. John's wort over standard antidepressants is the lack of significant side effects. Less than two percent of patients who take St. John's wort end up stopping the medication because of side effects. The most commonly noted side effects of St. John's wort are stomach complaints, allergic reactions and fatigue, but these occur very infrequently. Extensive use in Germany has not resulted in published case reports about serious drug interactions or toxicity after overdose. Long-term studies should help answer some of the questions concerning the long-term safety of St. John's wort.

Most authorities say that more than one antidepressant should not be taken at the same time. Doing so can result in a syndrome called the serotonin syndrome. The symptoms of this condition include sweating, agitation, confusion, lethargy, tremor, and muscle jerks. If such symptoms occur, consult your physician immediately. For this reason, care must be exercised when using St. John's wort with other antidepressants and many sources advise against this altogether.

Dosage and Cost

The starting dose of St. John's wort has usually been 900 milligrams per day. Three hundred milligram tablets are taken three times a day. This dose can be increased to a total of 1,800 milligrams every day. Like other antidepressants, it takes at least three to six weeks for the medication to work. A major benefit of St. John's wort is the fact that it costs less than ten dollars per month. This is at a dose of 900 milligrams per day. This is compared to the standard antidepressants that cost over 60 dollars per month. Since St. John's wort is a food additive, the Food and Drug Administration (FDA) does not regulate it. The actual quantity of the effective ingredient may very significantly from company to company. This problem can be partially overcome by buying what is called research-grade St. John's wort. The research grade hypericum may be available at some health food stores.


There is no question that St. John's wort is helpful for treating mild depression. The lack of side effects and extremely low-cost make it a reasonable option for treating mild depression. My main reservation is that people with severe depression may delay seeking treatment from their physician because they want to try St. John's wort first. I believe that all but the mildest form of depression should be under the direct supervision of a physician. Several medical conditions may present as depression. These conditions should be ruled-out before a diagnosis of depression is made. If you feel that you are depressed, discuss the diagnosis and treatment options with your physician. With numerous studies showing that St. John's wort is probably effective in treating depression, your physician may well suggest that you take St. John's wort. Since St. John's wort has so few side effects, I believe that compliance will be much better than with the standard antidepressants. I have been disappointed in the lack of results using St. Johns Wort for the most part. I only use it in very mild cases of depression where my patient doesn't want to take a regular antidepressant. For more information on the diagnosis and treatment of depression see http://www.freenet.scri.fsu.edu/HealthGazette/depress.html.


Linde K, et al. St John's wort for depression-an overview and meta-analysis of randomized clinical trials. BMJ 1996; 313:258-61.
De Smet PA and Nolen W. St. John's wort as an antidepressant. BMJ 1996 Aug 3: 313(7052): 241-2.
St. John's Wort. The Medical Letter Nov. 21, 1997 PP 107-8.
A better treatment for depression? University of California at Berkeley Wellness Letter. Vol 13, Issue 12 Sept 97, PP 8-9.
Staffeldt B - J Geriatr Psychiatry Neurol - 1994 Oct; 7 Suppl 1: S47-53.
The Hypericum Home Page. http://www.hypericum.com.
St. John's wort: A new alternative for depression? Int J Clin Pharmacol Ther 1999; 37:111.

The information provided above is offered as a community service about health-care issues and is not a substitute for individual consultation. Advice on individual problems should be obtained from your personal physician. This information is based on research by the author and represents his interpretation of the literature.

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Readers may send questions to our email address. This column is for informational purposes only and is not a substitute for professional or medical advice.

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