Recommended dosage

Because dosages of herbal preparations are not always standardized, it is important to discuss with a knowledgeable practitioner the most reliable form of St. John's wort. Recommendations call for 300-500 mg (of a standardized 0.3% hypericin extract) three times daily. It can take four to six weeks to notice the antidepressant effects of this preparation.

Alternatively, one to two teaspoons of dried St. John's wort can be put into a cup of boiling water and

St. John's wort flowers. (Photo Researchers, Inc. Reproduced by permission.) See color insert for color version of photo.

steeped for 10 minutes to make tea. The recommended dosage of tea is one to two cups daily. Again, four to six weeks may be necessary in order to notice improvement in symptoms of depression.


The following precautions should be considered and discussed with a knowledgeable practitioner before St. John's wort is taken:

• Some people may become more sensitive to the sun.

• Patients taking MAOIs must carefully avoid taking St. John's wort due to serious adverse effects of combining the two.

• Because the effects of St. John's wort are still being studied, pregnant and breast-feeding women should avoid its use.

• Depression can be a serious, even life-threatening, condition; therefore, it is imperative that depressed patients using St. John's wort are carefully monitored.

Side effects

People taking St. John's wort may develop one or all of the following side effects:

• skin rash due to sun sensitivity—the most common side effect

• headache, dizziness, dry mouth, constipation

• abdominal pain, confusion, sleep problems, and high blood pressure are less frequently experienced


Again, a knowledgeable professional should be consulted before St. John's wort is taken to determine the appropriateness of its use and avoid serious interactions.

Interactions include:

• Possible decrease in effectiveness of reserpine, warfarin, theophylline, immunosuppressant medications such as cyclosporine, and antiviral drugs such as indinavir.

• Dangerous interactions when used with other antide-pressant medicines (especially MAOIs), digoxin, and loperamide.

• Interactions with oral birth control pills. St. John's wort may interfere with the effectiveness of birth control pills, increasing the risk of pregnancy; an alternative form of birth control should be considered while taking St. John's wort. In addition, women taking both birth control pills and St. John's wort may notice bleeding between menstrual periods.

See also Depression and depressive disorders



Blumenthal, Mark and others, eds. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin: American Botanical Council, 1998.


Zink, Therese and Jody Chaffin. "Herbal 'Health' Products: What Family Physicians Need to Know." American Family Physician 58 (October 1, 1998): 1133.

Rosalyn Carson-DeWitt, M.D.

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