St. John’s Wort

Related Terms

• Amber touch-and-heal, balm-of-warrior's wound, balsana, bassant, Blutkraut, bossant, Calmigen®, corancillo dendlu, devil's scorge, Eisenblut, flor de São João, fuga daemonum, goatweed hartheu, heofarigo on, herba de millepertius, herba hyperici, herrgottsblut, hexenkraut, hierba de San Juan, hipericão, hipérico, hipericon, HP, isorhamnetin, Jarsin, Johanniskraut, klammath weed, Liebeskraut LI 160, lord God's wonder plant, millepertius pelicao, perforate, pinillo de oro, PM235, pseudohypericin, rosin rose, SJW extract LI 160, St. John's wort WS 5572, STW 3-VI, tenturotou, Teufelsflucht, touch and heal, Walpurgiskraut (German), witcher's herb, WS 5572.

Background

• Extracts of Hypericum perforatum L. (St. John's wort) have been recommended traditionally for a wide range of medical conditions. The most common modern-day use of St. John's wort is the treatment of depression. Numerous studies report St. John's wort to be more effective than placebo and equally effective as tricyclic antidepressant drugs in the short-term treatment of mild-to-moderate major depression (1-3 months). It is not clear if St. John's wort is as effective as selective serotonin reuptake inhibitor (SSRI) antidepressants such as sertraline (Zoloft®).
• Recently, controversy has been raised by two high-quality trials of St. John's wort for major depression that did not show any benefits. However, due to problems with the designs of these studies, they cannot be considered definitive. Overall, the scientific evidence supports the effectiveness of St. John's wort in mild-to-moderate major depression. The evidence in severe major depression remains unclear.
• St. John's wort can cause many serious interactions with prescription drugs, herbs, or supplements. Therefore, people using any medications should consult their healthcare providers including their pharmacist prior to starting therapy.

Evidence

*Key to grades: 

A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

For full grading rationale, click here.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.

Allergies

• Infrequent allergic skin reactions, including rash and itching, are reported in human studies.

Side Effects and Warnings

• In published studies, St. John's wort has generally been well tolerated at recommended doses for up to 1-3 months. The most common adverse effects include gastrointestinal upset, skin reactions, fatigue/sedation, restlessness or anxiety, sexual dysfunction (including impotence), sensitivity to light, dizziness, headache, and dry mouth. Several recent studies suggest that side effects occur in one to three percent of patients taking St. John's wort, and that the number of adverse events may be similar to placebo (and less than standard antidepressant drugs). Animal toxicity studies have found only non-specific symptoms such as weight loss. One small study reported elevated thyroid stimulating hormone (TSH) levels to be associated with taking St. John's wort.
• It has been reported that St. John's wort may cause psychiatric symptoms such as suicidal and homicidal thoughts.
• Delayed ejaculation has been reported in animal studies.

Pregnancy and Breastfeeding

• There is not enough scientific evidence available to recommend use during pregnancy or breastfeeding.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.

Interactions with Drugs

• St. John's wort interferes with the way the body processes many drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood in the short-term (causing increased effects or potentially serious adverse reactions) and/or decreased in the blood in the long-term (which can reduce the intended effects). Examples of medications that may be affected by St. John's wort in this manner include carbamazepine, cyclosporin, irinotecan, midazolam, nifedipine, simvastatin, theophylline, warfarin, or HIV drugs such as non-nucleoside reverse transcriptase inhibitors (NNRTIs) or protease inhibitors (PIs). The U.S. Food & Drug Administration (FDA) suggests that patients with HIV/AIDS on protease inhibitors or non-nucleoside reverse transcriptase inhibitors avoid taking St. John's wort.
• Taking St. John's wort with antidepressants may lead to increased side effects, including serotonin syndrome and mania. Serotonin syndrome is a condition defined by muscle rigidity, fever, confusion, increased blood pressure and heart rate, and coma. Mania is defined by symptoms of elevated or irritable mood, rapid speech or thoughts, increased activity, and decreased need for sleep. Using St. John's wort with MAOIs may also increase the risk of severely increased blood pressure. Caution is also advised when using St. John's wort with tricyclic antidepressants.
• Reports exist of altered menstrual flow, bleeding, and unwanted pregnancies in women taking birth control pills and St. John's wort at the same time. Although cases of interaction are rare, caution is advised when taking St. John's wort and coumarin-type anticoagulants (blood thinners). In general, individuals should check the package insert and speak with a qualified healthcare professional including a pharmacist about possible interactions with St. John's wort.
• St. John's wort may lead to increased risk of sun sensitivity when taken with other drugs such as antibiotics or birth control pills. A possible interaction with loperamide (Imodium®) has been reported; confusion and agitation occurred in one patient taking St. John's wort, loperamide, and the herb valerian (Valeriana officinalis). St. John's wort may interact with triptan-type headache medications. Examples include naratriptan (Amerge®), rizatriptan (Maxalt®), sumatriptan (Imitrex®), and zolmitriptan (Zomig®). In theory, St. John's wort may also interact with certain chemotherapy drugs such as anthracyclines. St. John's wort may increase the anti-inflammatory effects of COX2 inhibitor drugs or NSAIDS like ibuprofen (Motrin®).
• St John's wort may increase imatinib clearance. Thus, patients taking imatinib should avoid taking St John's wort. Concomitant use of enzyme inducers, including St John's wort, may necessitate an increase in the imatinib dose to maintain effectiveness.
• In higher doses, St. John's wort has been shown to decrease the blood concentrations of omeprazole, tolbutamide, caffeine, dextromethorphan, fexofenadine, carbamazepine, and cimetidine, among other medications. No relevant interaction has been seen with alprazolam, caffeine, tolbutamide, and digoxin by treatment with a low-hyperforin St. John's wort extract.
• Caution is also advised when taking benzodiazepine tranquilizers, opioids, P-glycoprotein regulated drugs, antibiotics, antivirals, anesthetics, antifungals, sedatives, or drugs used for anxiety, heart problems, or seizures. In general, individuals should check the package insert and speak with a qualified healthcare professional including a pharmacist about possible interactions with St. John's wort.

Interactions with Herbs and Dietary Supplements

• St. John's wort may interfere with the way the body processes certain herbs and supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood in the short-term, causing increased effects or potentially serious adverse reactions, or decreased in the blood in the long-term, which can reduce the intended effects.
• Taking St. John's wort with herbs or supplements with antidepressant activity may lead to increased side effects, including serotonin syndrome, mania, or severe increase in blood pressure. There is a particular risk of these interactions occurring with agents that possess possible monoamine oxidase inhibitory properties.
• St. John's wort may lead to increased risk of sun sensitivity when taken with capsaicin or other photosensitizing products. St. John's wort may interact with herbs that also possess cardiac glycoside properties and decrease blood levels.
• A possible interaction with the herb valerian (Valeriana officinalis) has been reported; confusion and agitation occurred in one patient taking St. John's wort, loperamide (Immodium®) and valerian. However, St. John's wort and valerian are often used together, with few reported of adverse events. In theory, due to the presence of tannins, St. John's wort may inhibit the absorption of iron.
• Although cases of interaction are rare, caution is advised when taking St. John's wort and herbs and supplements that may have blood-thinning effects.
• Caution is also advised when taking red yeast rice or any herb or supplements that is P-glycoprotein regulated. In general, individuals should speak with a qualified healthcare professional, including a pharmacist, about possible interactions with St. John's wort.
• Use cautiously when combining St. John's wort with herbs or supplements that have the following proposed effects: antibacterial, antiviral, or sedative. Also, St. John's wort may have a possible interaction with herbs or supplements used for anxiety, heart problems, or seizures.

Authors

• This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Selected References

Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Briese V, Stammwitz U, Friede M, et al. Black cohosh with or without St. John's wort for symptom-specific climacteric treatment--results of a large-scale, controlled, observational study. Maturitas 2007 Aug 20;57(4):405-14.
2. Chung DJ, Kim HY, Park KH, et al. Black cohosh and St. John's wort (GYNO-Plus) for climacteric symptoms. Yonsei Med J 2007 Apr 30;48(2):289-94.
3. Franklin M, Hafizi S, Reed A, et al. Effect of sub-chronic treatment with Jarsin (extract of St John's wort, Hypericum perforatum) at two dose levels on evening salivary melatonin and cortisol concentrations in healthy male volunteers. Pharmacopsychiatry 2006 Jan;39(1):13-5.
4. Kasper S, Volz HP, Moller HJ, et al. Continuation and long-term maintenance treatment with Hypericum extract WS 5570 after recovery from an acute episode of moderate depression--a double-blind, randomized, placebo controlled long-term trial. Eur Neuropsychopharmacol 2008;18(11):803-813.
5. Linde K, Berner MM, Kriston L. St John's wort for major depression. Cochrane Database Syst Rev 2008;(4):CD000448.
6. Muller T, Mannel M, Murck H, et al. Treatment of somatoform disorders with St. John's wort: a randomized, double-blind and placebo-controlled trial. Psychosom Med 2004;66(4):538-547.
7. Murphy PA, Kern SE, Stanczyk FZ, et al. Interaction of St. John's Wort with oral contraceptives: effects on the pharmacokinetics of norethindrone and ethinyl estradiol, ovarian activity and breakthrough bleeding. Contraception 2005 Jun;71(6):402-8.
8. Randlov C, Mehlsen J, Thomsen CF, et al. The efficacy of St. John's Wort in patients with minor depressive symptoms or dysthymia--a double-blind placebo-controlled study. Phytomedicine 2006 Mar;13(4):215-21.
9. Saarto T, Wiffen PJ. Antidepressants for neuropathic pain. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD005454.
10. Sardella A, Lodi G, Demarosi F, et al. Hypericum perforatum extract in burning mouth syndrome: a randomized placebo-controlled study. J Oral Pathol Med 2008;37(7):395-401.
11. Schempp CM, Windeck T, Hezel S, et al. Topical treatment of atopic dermatitis with St. John's wort cream--a randomized, placebo controlled, double blind half-side comparison. Phytomedicine 2003;10 Suppl 4:31-37.
12. Schulz V. Safety of St. John's Wort extract compared to synthetic antidepressants. Phytomedicine 2006 Feb;13(3):199-204.
13. Shelton RC, Keller MB, Gelenberg A, et al. Effectiveness of St John's wort in major depression: a randomized controlled trial. JAMA 4-18-2001;285(15):1978-1986.
14. Uebelhack R, Blohmer JU, Graubaum HJ, et al. Black cohosh and St. John's wort for climacteric complaints: a randomized trial. Obstet Gynecol 2006 Feb;107(2 Pt 1):247-55.
15. 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 6-11-2008;299(22):2633-2641.

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