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St Johns Wort


St. John’s wort is a plant with yellow flowers that has been used in traditional European medicine as far back as the ancient Greeks. The name St. John’s wort apparently refers to John the Baptist, as the plant blooms around the time of the feast of St. John the Baptist in late June.

Historically, St. John’s wort has been used for a variety of conditions, including kidney and lung ailments, insomnia, and depression, and to aid wound healing.

Currently, St. John’s wort is most often used as a dietary supplement for depression. People also use it as a dietary supplement for other conditions, including menopausal symptoms, attention-deficit hyperactivity disorder (ADHD), and obsessive-compulsive disorder. It is used topically for wound healing.

The flowering tops of St. John’s wort are used to prepare teas, tablets, capsules, and liquid extracts. Topical preparations are also available.

How Much Do We Know?

There has been extensive research on St. John’s wort, especially on its use for depression and on its interactions with medications. It has been clearly shown that St. John’s wort can interact in dangerous, sometimes life-threatening ways with a variety of medicines.

What Have We Learned?

The results of studies on the effectiveness of St. John’s wort for depression are mixed. For more information, see the NCCIH fact sheet St. John’s Wort and Depression.

St. John’s wort has also been studied for conditions other than depression. For some, such as ADHD, irritable bowel syndrome, and quitting smoking, current evidence indicates that St. John’s wort is not helpful. For others, such as menopausal symptoms, premenstrual syndrome, and obsessive-compulsive disorder, the evidence is inconclusive.

What Do We Know About Safety?

St. John’s wort can weaken the effects of many medicines, including crucially important medicines such as


Birth control pills

Cyclosporine, which prevents the body from rejecting transplanted organs

Digoxin, a heart medication

Some HIV drugs including indinavir

Some cancer medications including irinotecan

Warfarin, an anticoagulant (blood thinner).

Taking St. John’s wort with certain antidepressants or other drugs that affect serotonin, a substance produced by nerve cells, may lead to increased serotonin-related side effects, which may be potentially serious.

St. John’s wort may cause increased sensitivity to sunlight. Other side effects can include anxiety, dry mouth, dizziness, gastrointestinal symptoms, fatigue, headache, or sexual dysfunction.

Keep in Mind

Depression can be a serious illness. If you or someone in your family may have depression, consult a health care provider.

Although it is important to tell all your health care providers about any complementary health approaches you use, this is especially crucial for St. John’s wort because this herb interacts with so many medicines. Interactions with St. John’s wort can weaken the effects of lifesaving medicines or cause dangerous side effects.

Key References

  • Cott JM. St. John’s wort. In: Coates PM, Betz JM, Blackman MR, et al., eds. Encyclopedia of Dietary Supplements. 2nd ed. New York, NY: Informa Healthcare; 2010:727-737.
  • Borrelli F, Izzo AA. Herb-drug interactions with St. John’s wort (Hypericum perforatum): an update on clinical observations. The AAPS Journal. 2009;11(4):2009;11(4):710-727.
  • Gurley BJ, Fifer EK, Gardner Z. Pharmacokinetic herb-drug interactions (part 2): drug interactions involving popular botanical dietary supplements and their clinical relevance. Planta Medica. 2012;78(13):1490-1514.
  • Linde K, Berner MM, Kriston L. St. John’s wort for major depression. Cochrane Database of Systematic Reviews. 2008;(4):CD000448 [edited 2009]. Accessed at is external) on April 27, 2015.
  • Parsons A, Ingram J, Inglis J, et al. A proof of concept randomised placebo controlled factorial trial to examine the efficacy of St. John’s wort for smoking cessation and chromium to prevent weight gain on smoking cessation. Drug and Alcohol Dependence. 2009;102(1-3):116-122.
  • Rapaport MH, Nierenberg AA, Howland R, et al. The treatment of minor depression with St. John’s wort or citalopram: failure to show benefit over placebo. Journal of Psychiatric Research. 2011;45(7):931-941.
  • Saito YA, Rey E, Almazar-Elder AE, et al. A randomized, double-blind, placebo-controlled trial of St. John’s wort for treating irritable bowel syndrome. American Journal of Gastroenterology. 2010;105(1):170-177.
  • Sarris J, Fava M, Schweitzer I, et al. St John’s wort (Hypericum perforatum) versus sertraline and placebo in major depressive disorder: continuation data from a 26-week RCT. Pharmacopsychiatry. 2012;45(7):275-278.
  • Sood A, Ebbert JO, Prasad K, et al. A randomized clinical trial of St. John’s wort for smoking cessation. Journal of Alternative and Complementary Medicine. 2010;16(7):761-767.
  • St. John’s wort. In: Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Integrative Medicine Communications; 2000:359-366.
  • St. John’s wort. Natural Medicines Web site. Accessed at on April 27, 2015. [Database subscription].
  • Weber W, Vander Stoep A, McCarty RL, et al. Hypericum perforatum (St. John’s wort) for attention-deficit/hyperactivity disorder in children and adolescents: a randomized controlled trial. JAMA. 2008;299(22):2633-2641.


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