St. John’s Wort Information

St. John’s Wort Information

St. John’s wort may prevent and improve symptoms of mild and moderate depression. St. John’s may be helpful in treating sleep disorders and viral infections.

Detailed Information

  • St. John’s wort appears to be effective in easing anxiety and depression.
  • The xanthones and flavonoids contained in the herb are linked to its anti-depressant effects.
  • St. John’s wort is also available as a red olive oil extract, used to settle nerves. The red oil is also used externally to bring down inflammation, such as hemorrhoids.
  • St. John’s wort contains about 10% tannin (an astringent), which appears to contribute to wound-healing and the relief of hemorrhoids when used topically.
  • St. John’s wort is also used as a diuretic.

Toxicity/Possible Side Effects

Less than 1% of the proponents of St. John’s wort complain of side effects, but here are the most common ones reported to date:

  • If taken for extended periods, the active constituent hypericin found in St. John’s wort can cause sensitivity to sunlight.
  • Dermatitis, inflamed mucous membranes, skin burning and/or blistering can result, especially in light-skinned individuals, when exposed to the sun.
  • Headaches, stiff neck, nausea, vomiting and high blood pressure can result via interaction with the following: the amino acid tryptophan (which is found in soya protein, cottage cheese, fish, beef liver, lamb, peanuts, pumpkin and sesame seeds, and lentils); the amino acid tyramine (which is found in cheese, chocolate, eggs, wheat, peanuts, citrus fruits, tomatoes, pork, sausages, chicken liver, beef, fava beans, vanilla, yeast, soy sauce, beer and red wine); amphetamines; asthma inhalants; cold or hay fever medicines; diet pills; narcotics and nasal decongestants.

Other Facts

  • St. John’s wort is derived from Hypericum perforatum.
  • This aromatic perennial herb with golden flowers is a member of the Hypericaceae family.
  • St. John’s wort gained its namesake from the age-old story that the plant supposedly sprung from the blood of St. John the Baptist when he was beheaded.
  • Parts used are the leaves and flowering tops.
  • St. John’s wort is the most commonly prescribed antidepressant in Germany, with two to three million prescription written every year.


  • SAD and St. John’s wort. – Two groups diagnosed with seasonal affective disorder (SAD – depression peaking in fall/winter and declining during spring/summer) were treated with 900 mg of St. John’s wort plus 2 hours’ exposure to bright light or 2 hours of dim light over 4 weeks. Both groups improved significantly, suggesting that St. John’s wort may be an effective therapy in patients with SAD. J Geriatr Psychiatry Neurol, Oct. 1994.
  • Serotonin and St. John’s wort. – According to this German study, the anti-depressant activity of St. John’s wort extract is due to an inhibition of the uptake of the neurotransmitter serotonin by receptors in the brain. Arzneimittelforschung, Nov. 1995.
  • Depression and St. John’s wort. – In this study, extracts of St. John’s wort appear to be more effective than a placebo in treating mild to moderately severe depression. The herb was shown to be as effective as standard anti-depressant medications, and it had a lower incidence of adverse side effects. Further studies need to be conducted on more well-defined groups of patients and using various extracts and forms of St. John’s wort. BMJ, Aug. 3, 1996.

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last update: March 2010