St. John's Wort

Keywords: hypericum herb, klamath weed, goat weed, depression, anxiety

© Steven Foster

On this page:

• Introduction
• What the Science Says
• Side Effects and Cautions
• Sources
• For More Information

Introduction

This fact sheet provides basic information about the herbA plant or part of a plant used for its flavor, scent, or potential therapeutic properties. Includes flowers, leaves, bark, fruit, seeds, stems, and roots. St. John's wort—common names, uses, potential side effects, and resources for more information.

Common Names—St. John's wort, hypericum, Klamath weed, goatweed

Latin Name—Hypericum perforatum

St. John's wort is a plant with yellow flowers whose medicinal uses were first recorded in ancient Greece. 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 centuries to treat mental disorders and nerve pain. St. John's wort has also been used for malaria, as a sedative, and as a balm for wounds, burns, and insect bites. Today, St. John's wort is used as a folk or traditional remedy for depression, anxiety, and/or sleep disorders.

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.

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What the Science Says

Although some studies of St. John's wort have reported benefits for depression, others have not. For example, a large study sponsored by NCCAM found that the herb was no more effective than placebo in treating major depression of moderate severity, and a study co-funded by NCCAM and the National Institute of Mental Health found that neither St. John's wort nor a standard antidepressant medication relieved symptoms of minor depression better than a placebo.

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Side Effects and Cautions

• Research has shown that St. John's wort interacts with many medications in ways that can interfere with their intended effects. Examples of medications that can be affected include:
  • Antidepressants
  • Birth control pills
  • Cyclosporine, which prevents the body from rejecting transplanted organs
  • Digoxin, a heart medication
  • Indinavir and possibly other drugs used to control HIV infection
  • Irinotecan and possibly other drugs used to treat cancer
  • Seizure-control drugs, such as phenytoin and phenobarbital
  • Warfarin and related anticoagulants.
• Taking St. John's wort with certain antidepressants may lead to increased serotonin-related side effects, which may be potentially serious.
• St. John's wort is not a proven therapy for depression. If depression is not adequately treated, it can become severe. Anyone who may have depression should see a health care provider. There are effective proven therapies available.
• Tell all your health care providers about any complementary and alternative approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care. For tips about talking with your health care providers about complementary and alternative medicineA group of diverse medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine. Complementary medicine is used together with conventional medicine, and alternative medicine is used in place of conventional medicine., see NCCAM's Time to Talk campaign.

Search the scientific literature for potential herb-drug interactions

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Sources

• De Smet PA. Herbal remedies. New England Journal of Medicine. 2002;347(25):2046–2056.
• Hypericum Depression Trial Study Group. Effect of Hypericum perforatum (St. John's wort) in major depressive disorder: a randomized controlled trial. Journal of the American Medical Association. 2002;287(14):1807–1814.
• National Center for Complementary and Alternative Medicine. St. John's Wort and Depression. National Center for Complementary and Alternative Medicine Web site. Accessed at nccam.nih.gov/health/stjohnswort/sjw-and-depression.htm on June 3, 2010.
• 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;45:931–941.
• St. John's wort. In: Blumenthal M, Goldberg A, Brinckman J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Lippincott Williams & Wilkins; 2000:359–366.
• St. John's wort. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on February 15, 2010.
• St. John's wort (Hypericum perforatum L.). Natural Standard Database Web site. Accessed at www.naturalstandard.com on February 15, 2010.

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For More Information

• Using Dietary Supplements Wisely

NCCAM Clearinghouse

The NCCAM Clearinghouse provides information on CAM and NCCAM, 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.

Toll-free in the U.S.: 1-888-644-6226
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PubMed^®

A service of the National Library of Medicine (NLM), PubMed^® contains publication information and (in most cases) brief summaries of articles from scientific and medical journals.

Web site: www.ncbi.nlm.nih.gov/sites/entrez

NIH Office of Dietary Supplements

Web site: ods.od.nih.gov

NIH National Library of Medicine's MedlinePlus

St. John's Wort Listing: www.nlm.nih.gov/medlineplus/druginfo/natural/329.html

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This publication is not copyrighted and is in the public domain. Duplication is encouraged.

NCCAM Publication No. D269
Created July 2005
Updated November 2011

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