St. John's Wort: Sometimes friend, Sometimes Foe

St. John's Wort: Sometimes friend, Sometimes Foe

St. John's wort has recently become enormously popular and is being used successfully to treat a variety of illnesses and health conditions. It is primarily used to treat mood disorders, such as mild to moderate depression, seasonal affective disorder, anxiety, and insomnia. St. John's wort is also being used for treating wounds, burns, and hemorrhoids. The herb is readily available over-the-counter in a variety of forms, including capsules, liquids, lotions, teas, and powders. Although St. John's wort is widely used, easily accessible, and a natural medicine, a word of caution is in order, because like any medicine, St. John's wort may be harmful too.

As St. John's wort is studied more, experts are concerned about its potential for undesirable effects. One preliminary finding shows that high concentrations of the herb may damage male fertility. Other research indicates that St. John's wort may have a role in the development of cataracts. The herb appears to damage proteins in the eyes when combined with bright sunlight. If you take St. John's wort you should wear a hat and wrap-around sunglasses when you're outside in bright sunlight.

While St. John's wort has been shown to relieve symptoms of depression, you should not take it if you are already taking an antidepressant. Talk with your doctor if you think you suffer from depression and feel you need medical help or if you are interested in replacing your antidepressant with St. John's wort. Do not attempt to treat your depression with St. John's wort if it is severe or if you feel suicidal.

St. John's wort should not be taken if you are pregnant, breast-feeding, or if you take L-dopa or 5-hydroxytryptophan (5-HTP). You should also know that the side effects of this herb may include:

  • Abdominal pain, bloating, or constipation
  • Nausea or vomiting
  • Dizziness
  • Dry mouth
  • Hives, skin rashes or irritation
  • Sleeping problems
  • Elevated blood pressure
  • Fatigue
  • Restlessness

The bottom line: keep in mind that although St. John's wort is a natural substance that is available over-the-counter, you should always treat it like a medicine and consult your doctor if you are planning to use it.


L-dopa: Levodopa, a drug used in for treating the shaking and muscular rigidity associated with Parkinson's disease

5-hydroxytryptophan (5-HTP): a natural compound produced by the body from an amino acid (tryptophan). It is used to aid sleep, and in the treatment of fibromyalgia and depression.

Suggested Resources

The Natural Pharmacist: Your Complete Guide to St. John's Wort and Depression by Steven Bratman (Prima Publishing 1999)


Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin, TX: The American Botanical Council and Boston, MA: Integrative Medicine Communications; 1998:214-215.

Fugh-Berman A. Infertility from herbs? Alternative Therapies in Women's Health. 1999;1(5):38-39.

Integrative Medicine Access: Professional Reference to Conditions, Herbs & Supplements. Newton, Mass: Integrative Medicine Communications; 2000.

Lantz MS, Buchalter E, Giambanco V. St. John's wort and antidepressant interactions in the elderly. J Geriatr Psychiatry Neurol. 1999;12:7-10.

Linde K, Mulrow CD. St. John's wort for depression (Cochrane Review). In: The Cochrane Library, Issue 4, 1998. Oxford: Update Software.

Miller AL. St. John's wort (Hypericum perforatum): clinical effects on depression and other conditions. Alt Med Rev. 1998; 3(1):18-26.

Ondrizek RR, Chan PJ, Patton WC, King A. An alternative medicine study of herbal effects on the penetration of zona-free hamster oocytes and the integrity of sperm deoxyribonucleic acid. Fertil Steril. 1999;71(3):517-522.

Roberts JE, Wang RH, Tan IP, Datillo M, Chignell CF. Hypericin (active ingredient in St. John's wort) photo-oxidation in lens proteins. Photochem Photobiol. 1999;69(suppl 6):S42.

Schempp CM, Pelz K, Wittmer A, Schopf E, Simon JC. Antibacterial activity of hyperforin from St. John's wort, against multiresistant Staphylococcus aureus and gram-positive bacteria. Lancet. 1999;353(9170):2129.

Schultz V, Hansel R, Tyler VE. Rational Phytotherapy. A Physician's Guide to Herbal

Medicine. New York: Springer. 1998.

Review Date: December 1999
Reviewed By: Integrative Medicine editorial

Copyright © 2004 A.D.A.M., Inc

The publisher does not accept any responsibility for the accuracy of the information or the consequences arising from the application, use, or misuse of any of the information contained herein, including any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise. No warranty, expressed or implied, is made in regard to the contents of this material. No claims or endorsements are made for any drugs or compounds currently marketed or in investigative use. This material is not intended as a guide to self-medication. The reader is advised to discuss the information provided here with a doctor, pharmacist, nurse, or other authorized healthcare practitioner and to check product information (including package inserts) regarding dosage, precautions, warnings, interactions, and contraindications before administering any drug, herb, or supplement discussed herein.

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