This page contains general information. This material is NOT complete, and it does not cover all possible precautions, side effects, or interactions. You should always consult your physician when making decisions about your health.
St John's wort is a unique antidepressant that is effective, inexpensive, and available over the counter. It has been used for medicinal purposes since the time of Ancient Greece, when it was used to treat low mood, lack of energy, and poor sleep. The plant's scientific name is Hypericum perforatum. It's a yellow-flowering perennial herb that grows wild in meadows.
St John's wort is as effective as prescribed antidepressants for the treatment of mild depression.,This has been proven in numerous studies with thousands of patients. One meta-analysis looked at the combined results of 37 published trials and concurred that St John's wort is as effective as prescribed antidepressants for the treatment of mild depression. The study also concluded that St John's wort has fewer side effects than most antidepressants.
Further studies have shown that St John's wort works on serotonin and dopamine, which are the same neurotransmitters other antidepressants work on. St John's wort is available over the counter in North America, but it is available only by prescription in parts of Europe.
Over-the-counter supplements are unregulated in the US. St John's wort is not approved for the treatment of depression by the US Food and Drug Administration. Therefore St John's wort is classified as a dietary supplement, and all dietary supplements are unregulated in the US. They are not tested for safety or purity.
That means it's perfectly legal to label inert pills of starch as St John's wort. Therefore, if you decide to use St. John's wort, use an over-the-counter brand that you trust.
The side effects of St. John's wort are usually mild and temporary. They often subside after a few weeks. However, you should report any unusual reactions or side effects to your doctor immediately. The common side effects of St. John's wort are the following:
St John's wort is not recommended in the following cases:
St John's wort reduces the blood levels of the following medications:
You may still be able to take St. John's wort if you take these medications. St John's wort is not unique in having these interactions. Most antidepressants have the same effect. Yet antidepressants are sometimes prescribed in conjunction with these medications. It may mean that the dosage of the other medication has to be monitored and possibly increased.
(St. John's wort and prescribed antidepressants reduce the blood levels of these medications because they interact with the Cytochrome P450 enzymes that break down medications in the liver.)
St John's wort is usually available in 300 mg capsules. Approximately 900-1200 mg is needed to reduce the symptoms of depression. Discuss your plans with your doctor. This is one possible dosage regime.
For more information about antidepressants in general, please look at the webpage on antidepressants.
1) K Linde, CD Mulrow, M Berner, M Egger, "St John's wort for depression," Cochrane Database Syst Rev. 2005 Apr 18;(2):CD000448.
2) S Lawvere, MC Mahoney, "St. John's Wort," American Family Physician, Dec. 1, 2005:2249-2254.