St. John's Wort
St. John's wort: what NIH says about mild to moderate depression, and its dangerous interactions with antidepressants, birth control, transplant and other medicines.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
St. John's wort can interact in dangerous, sometimes life-threatening ways with many medicines. Do not start it, and do not stop a prescribed medicine, without talking to a pharmacist or clinician. [1]
Overview
St. John's wort is a yellow-flowered plant used in Greek, Islamic and Chinese traditional medicine for depression, stomach ulcers, colds and wound healing. Today it is most widely promoted for symptoms of depression, and also for menopause symptoms and skin conditions. [1]Names and parts
Hypericum perforatum. [1][2]What the research shows (NIH summary)
| Use | What NIH says | Strength of evidence |
|---|---|---|
| Mild to moderate depression | Appears more effective than placebo and as effective as standard antidepressants. Uncertain for severe depression or beyond 12 weeks. [1] | Better than placebo for mild to moderate depression |
| Menopausal hot flashes, somatic symptom disorder | Small numbers of studies suggest it may help. [1] | Limited |
| ADHD, IBS, OCD, PMS, smoking cessation, wound healing | Only a small amount of research; not clearly shown to help. [1] | Insufficient |
Depression can be serious. If you or someone you know may have depression, see a health care provider rather than self-treating.
Safety and interactions
- For most adults not taking medicine it appears safe for up to 12 weeks, and some studies suggest a year or more. Large oral doses or use on skin might cause severe skin reactions after sun exposure. Other side effects: diarrhea, dizziness, trouble sleeping, restlessness and skin tingling. [1]
- It can weaken the effects of many medicines, including some antidepressants (such as amitriptyline and bupropion), birth control pills, cyclosporine (to prevent transplant rejection), some seizure medicines (phenytoin, carbamazepine), some heart medicines (digoxin, ivabradine), some HIV drugs (indinavir, nevirapine), some cancer medicines (irinotecan, imatinib, docetaxel), warfarin and certain statins such as simvastatin. [1]
- Taking it with certain antidepressants or other drugs that affect serotonin may increase serotonin-related side effects, which can be serious. [1]
- It may be unsafe in pregnancy because it may increase the risk of birth defects. Breastfed infants of mothers who take it can experience colic, drowsiness and lethargy. [1]
Frequently asked questions
Does St. John's wort work for depression?
NIH says it appears more effective than placebo and as effective as standard antidepressants for mild or moderate depression, but uncertain for severe depression. [1]
Can I take St. John's wort with my medicine?
Often not. It can weaken many medicines. Ask a pharmacist first. [1]
References
- National Center for Complementary and Integrative Health (NIH). St. John's Wort: Usefulness and Safety. Page last updated May 2025.
- GBIF Secretariat. GBIF Backbone Taxonomy. Names checked 2026-10-22 through the GBIF species match service.