How St. John's wort (herbal supplement) Affects Your Medications
Tell your provider and pharmacist before using St. John's wort — it interacts with a wide range of prescription medicines.
This interaction is generally considered major in severity.
How It Happens
St. John's wort induces CYP3A4 and P-glycoprotein, which can lower levels of many drugs (reducing their effect), and with antidepressants can add serotonin, raising the risk of serotonin syndrome.
What to Do
Tell your provider and pharmacist before using St. John's wort — it interacts with a wide range of prescription medicines.
Medication Classes Affected
Specific Medications to Watch
Vitamin K antagonist anticoagulant
Factor Xa inhibitor anticoagulant
Factor Xa inhibitor anticoagulant
SSRI antidepressant
SSRI antidepressant
SSRI antidepressant
Calcineurin inhibitor immunosuppressant
Calcineurin inhibitor immunosuppressant
Cardiac glycoside
Sources
This information is educational — not medical advice.
This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.