St John's wort: what it is and how much people take
St John's wort is a yellow-flowered plant, Hypericum perforatum. Studies have looked at mild to moderate depression; evidence for other uses is limited. It can interact dangerously with many medicines, including antidepressants, birth control pills, blood thinners, statins and some heart, seizure, HIV and cancer drugs. Talk to a doctor or pharmacist before taking it.
General information, not medical advice. Check with a doctor or pharmacist before taking a supplement, especially if you are pregnant or breastfeeding, take any medicine, or are under 18.
How much people take
| What studies looked at | Studies have looked at mild to moderate depression; evidence for other uses is limited. |
|---|---|
| Official upper limit | None set |
Cautions and interactions
- It can interact dangerously with many medicines, including antidepressants, birth control pills, blood thinners, statins and some heart, seizure, HIV and cancer drugs. Talk to a doctor or pharmacist before taking it.
- It can make skin more sensitive to sun.
Quick answers
- What is St John's wort?
- St John's wort is a yellow-flowered plant, Hypericum perforatum.
- What has St John's wort been studied for?
- Studies have looked at mild to moderate depression; evidence for other uses is limited.
- Is St John's wort safe?
- It can interact dangerously with many medicines, including antidepressants, birth control pills, blood thinners, statins and some heart, seizure, HIV and cancer drugs. Talk to a doctor or pharmacist before taking it. It can make skin more sensitive to sun.
Sources
- NCCIH (US National Institutes of Health)
https://www.nccih.nih.gov/health/st-johns-wort
Ask Supplement Check yourself
Type a supplement, a dose, or a product name, and get the amounts studies used, any official ceiling and the cautions. Open Supplement Check, free, no sign-up.
In Claude or any app that takes MCP connectors, add https://goodturn-mcp.pages.dev/supplementcheck/mcp and ask: “Is St John's wort safe?”