St. John's wort
Summary
St. John's wort extracts beat placebo for mild to moderate depression in meta-analyses (grade B) and matched standard antidepressants. But it interacts dangerously with many medicines, including birth control pills, transplant drugs, warfarin and antidepressants. Depression needs clinical care, so we do not link to products.
Key facts
- A flowering plant; extracts are standardized to hypericin and hyperforin[2]
- Weakens many medicines, including birth control pills, cyclosporine, warfarin, some HIV, heart, seizure and cancer drugs[3]
- Taken with some antidepressants or other serotonergic drugs it can cause serious serotonin-related side effects[3]
- Because of these interactions and because depression needs clinical care, this page carries no Where-to-buy block[3]
- 2 graded human outcomes on this page
- October 11, 2026
How it works
ProposedHypericum extracts contain compounds such as hypericin and hyperforin; how the herb affects mood is not settled. Its interactions come from weakening the effects of many other medicines.[2][3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Major depression (response) | Improved | Grade B | Systematic review · n = 5,489 · 2008 Adults with major depression in 29 trials Form: Hypericum extracts · Dose: Varied across trials · Duration: Varied Larger placebo-controlled trials: response rate ratio 1.28 (95% CI 1.10–1.49); versus SSRIs, response was similar (RR 1.00) Results from German-speaking countries were more favourable. | 18843608 (opens PubMed)Source [1] |
| Mild to moderate depression | Improved | Grade B | Systematic review · n = 2,922 · 2016 Adults with mild to moderate major depressive disorder (placebo-controlled comparisons) Form: Hypericum extracts · Dose: Varied across trials · Duration: Varied More responders than placebo (RR 1.53, moderate-quality evidence, high heterogeneity); similar effectiveness to antidepressants with fewer adverse events. | 27589952 (opens PubMed)Source [2] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Standardized hypericum extract (hypericin/hyperforin) | Varies[3][2] | No head-to-head human absorption data between products in our sources.[3][2] | Side effects can include diarrhea, dizziness, trouble sleeping, restlessness and sun sensitivity at large doses.[3][2] | Mild to moderate depression |
Studied doses
Doses studied in human trials ranged from trial to trial, using many different standardized hypericum extracts; the reviews pooled them rather than defining one dose.[1][2]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Birth control pillsNIH fact sheetSt. John’s wort can weaken their effect.[3]
- Cyclosporine and other transplant drugsNIH fact sheetCan weaken cyclosporine, which prevents organ rejection.[3]
- WarfarinNIH fact sheetCan weaken the anticoagulant effect.[3]
- Antidepressants and other serotonergic drugsNIH fact sheetCan weaken some antidepressants (amitriptyline, bupropion) and, with serotonergic drugs, cause serious serotonin-related side effects.[3]
- Heart, seizure, HIV, cancer drugs and some statinsNIH fact sheetCan weaken digoxin, ivabradine, phenytoin, carbamazepine, indinavir, nevirapine, irinotecan, imatinib, docetaxel and simvastatin.[3]
Who should be careful
- Anyone taking prescription medicine
- It weakens many crucial medicines; talk to a clinician or pharmacist before using it.[3]
- Pregnancy and breastfeeding
- NCCIH says it may be unsafe in pregnancy (possible birth defects), and breastfed infants have had colic, drowsiness and lethargy.[3]
- Depression
- Depression can be serious and needs clinical care; do not use the herb in place of it.[3]
- Sun exposure
- Large oral doses may cause severe skin reactions after sun exposure.[3]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Frequently asked questions
Does St. John's wort work for depression?
Meta-analyses found more responders than placebo in mild to moderate depression and similar results to standard antidepressants.[1][2]
Why is St. John's wort risky?
It weakens many medicines, including birth control, transplant drugs and warfarin, and can cause serotonin toxicity with some antidepressants.[3]
Can I take it with my antidepressant?
Combining it with antidepressants or other serotonergic drugs can cause serious side effects; ask your prescriber.[3]
Why is there no product link on this page?
Because of its many drug interactions and because depression needs clinical care, we do not link to St. John’s wort products.[3]
Is it safe in pregnancy?
NCCIH says it may be unsafe in pregnancy and can affect breastfed infants.[3]
Sources
- [1]St John's wort for major depression.. Cochrane Database Syst Rev, 2008. systematic-review
- [2]A systematic review of St. John's wort for major depressive disorder.. Syst Rev, 2016. systematic-review
- [3]St. John's Wort. National Center for Complementary and Integrative Health (NIH), 2025. fact-sheet
What changed
- First draft. Every PMID checked against NCBI E-utilities (title, year and journal taken from the PubMed record) and abstracts read for each cited row. Product details in Where to buy read from the brand page on the date shown. Self-reviewed in a second strict pass (no independent reviewer yet).