St. John’s wort is a plant with yellow flowers whose medicinal uses were first recorded in ancient Greece. The flowering tops of St. John’s wort are used to prepare teas, tablets, and capsules containing concentrated extracts. Liquid extracts and topical preparations are also used. St. John’s wort interacts with many medications, making the medications less effective.
This fact sheet provides basic information about St. John’s wort—common names, usefulness and safety, and resources for more information.
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Common Names: St. John’s wort, hypericum, Klamath weed, goatweed
Background
- 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
- Antidepressants
- 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.
For More Information
NCCIH Clearinghouse
The NCCIH Clearinghouse provides information on NCCIH and complementary and integrative health approaches, including publications and searches of Federal databases of scientific and medical literature. The Clearinghouse does not provide medical advice, treatment recommendations, or referrals to practitioners.
PubMed®
A service of the National Library of Medicine, PubMed® contains publication information and (in most cases) brief summaries of articles from scientific and medical journals. For guidance from NCCIH on using PubMed, see How To Find Information About Complementary Health Approaches on PubMed.
Office of Dietary Supplements (ODS), National Institutes of Health (NIH)
ODS seeks to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, supporting research, sharing research results, and educating the public. Its resources include publications (such as Dietary Supplements: What You Need to Know), fact sheets on a variety of specific supplement ingredients and products (such as vitamin D and multivitamin/mineral supplements), and the PubMed Dietary Supplement Subset
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 http://www.thecochranelibrary.com(link 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 naturalmedicines.therapeuticresearch.com 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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