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St. John's Wort for Depression

Taking the Hype Out of Hypericum


Updated June 17, 2014

Hypericum perforatum, Nature's Prozac, St. John's wort--whatever you call it it's the newest wonder herb on the scene and it promises to treat depression safely and without the troublesome side-effects of prescription medications. But does natural really equate with safe?

St. John's wort actually isn't new. It has been used for thousands of years as a folk remedy for what we now recognize as the symptoms of depression--worry, nervousness, and sleep disturbances. In addition, it is the most researched herbal depression treatment in recent times. In Germany, where the majority of clinical research was conducted, it is prescribed 50% of the time for mild to moderate depression. In comparison, Prozac only prescribed 2% of the time; In the British Journal of Medicine twenty-three separate clinical trials have been published concerning St. John's wort; And in the United States, the National Institute of Mental Health (NIMH) is planning studies of its own. The general consensus seems to be that St. John's wort is a promising treatment for depression. In the meantime, how can we be certain that this non-prescription remedy isn't harmful?

The truth is, no substance is totally safe. Quantity makes all the difference. Small amounts of chlorine gas bind with sodium to form table salt. Pure chlorine gas inhaled in large quantities, however, is a deadly poison. Even a totally natural compound like Hypericin, the active ingredient in St. John's wort, must be used with the same care exercised with any drug. The following are general guidelines for safe and effective usage of St. John's wort.

Used for: Mild to moderate depression

Cautions and warnings:

  • If you are currently taking a prescription or over-the-counter medication, consult a physician before using St. John's wort.
  • Do not attempt to self-diagnose depression.
  • Do not use for severe depression, especially if suicidal feelings are present.
  • Do not take for bipolar depression.
  • Do not stop prescription medications without first consulting a physician.

Pregnancy and breastfeeding: Do not take if pregnant or lactating. There is insufficient data on its safety.

Possible side effects:

  • Upset Stomach (0.7% in clinical studies)
  • Allergic reactions (less than 0.6% in clinical studies)
  • Fatigue (less than 0.5% in clinical studies)
  • Photosensitivity - St. John's wort has been known to increase sensitivity to sunlight in animals that have eaten large quantities of this plant. This effect, known as phototoxicity, should especially be kept in mind you have a prior sensitivity to sunlight, or if you are taking photosensitizing drugs like Chlorpromazine and Tetracyclines. There have been no documented cases of St. John's wort induced photosensitivity in humans, but care should be taken not to exceed recommended dosages.

Common side effects associated with prescription medicines not reported with St. John's wort: Sexual dysfunction, adverse interaction with alcohol, dry mouth, and headache.

Drug Interactions: AS WITH ANY MEDICATION, IF YOU ARE TAKING ANY PRESCRIPTION OR OVER-THE-COUNTER DRUG, CONSULT A PHYSICIAN OR PHARMACIST ABOUT POSSIBLE DRUG INTERACTIONS. While the mechanism by which St. John's wort works is not known, it is thought to be at least in part an SRI (serotonin reuptake inhibitor). Treat it as you would any other SRI. Do not use St. John's wort in conjunction with a MAOI as this may lead to a dangerous rise in blood pressure. It may also cause a condition known as Serotonin Poisoning or Serotonin Syndrome, which results from an excessive build up of serotonin in the brain. Symptoms of Serotonin Syndrome include sweating, agitation, confusion, lethargy, tremor, and muscle jerks. If any of these symptoms occur consult a physician immediately. After discontinuing use of a MAOI, wait at least four weeks before taking St. John's wort.

Update, 6/19/98: In this article, I stated that St. John's wort is thought to work like an SSRI. The current feeling among researchers is that it exhibits properties of both a mild MAOI and an SSRI. The jury is still out, however, as to just what it's mechanism of action really is. Until such time that this becomes known, it is still wise to be aware of potential drug interactions between St. John's wort and other antidepressants. The prudent way to use it is to allow time for your current medication to be fully eliminated from your body (check with your doctor, pharmacist, or a good drug reference to determine this) prior to beginning St. John's wort.

Update, 8/18/00: It has recently been advised that certain drugs may interact with St. John's wort. For the full story, please read St. John's Wort Revisited.

Recommended daily dosage (based on a preparation standardized to 0.3%):

  • Adult or adolescent - 300 mg 3 times a day. Allow at least 6 weeks for it to take full effect.
  • Child - Administer to children only under a physician's care

Overdosage: There have been no reported cases in humans. Symptoms of phototoxicity or serotonin syndrome would be probable. Seeks medical care immediately.

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