St. John's wort
St. John's Wort is one of the most dangerous supplements for drug interactions — it reduces effectiveness of birth control, HIV medications, blood thinners, and antidepressants. Learn what to avoid.
St. John's wort (Hypericum perforatum) is one of the most interaction-heavy supplements because it induces CYP3A4 and P-glycoprotein, reducing levels of many prescription drugs—including hormonal contraceptives, HIV antiretrovirals, immunosuppressants, anticoagulants, and some antidepressants. The result can be unintended pregnancy, transplant rejection, or loss of infection control. This supplement should never be added casually to a medication stack.
| Drug class | Risk | Why | Action |
|---|---|---|---|
| Birth control | Contraceptive failure | Enzyme induction | Avoid combination |
| HIV therapy | Virologic failure | Reduced drug levels | Never combine |
| Transplant meds | Rejection risk | Level drops | Never combine |
| Antidepressants | Serotonin toxicity risk | Combination variability | Psychiatry guidance only |
Source: NIH ODS (St. John’s wort); FDA interaction warnings for prescription medicines.
If you take any prescription, ask first. This herb is not a “mood vitamin.”
Assume contraceptive failure. Do not rely on pills/patch/ring if enzyme induction is present.
Emergency care for serotonin symptoms. Agitation, fever, clonus, confusion are emergencies.
Tell every surgeon and anesthesiologist. Herb discontinuation timing may be required.
Mood support blends and “natural antidepressant” marketing often hide St. John’s wort among other herbs.
NutriAudit helps users discover hidden St. John’s wort in proprietary blends before harm occurs.
St. John’s wort can reduce levels of oral contraceptives, immunosuppressants, anticoagulants, antiretrovirals, and many antidepressants—failure modes include pregnancy, transplant rejection, and subtherapeutic anticoagulation.
Induction persists for days after stopping; surgery and travel are bad moments to “trial” without pharmacy input.
Combining SJW with SSRIs/SNRIs/MAOIs/triptans is dangerous. “Natural” labeling does not reduce pharmacologic potency.
Phototoxic rashes and hypomania signals deserve discontinuation and clinician contact, not dose increases.
Safety is dominated by drug interactions—not the symptom label on the bottle.
Induction persists days to weeks after stopping—pharmacist half-life guidance matters.
Generally no—serotonin syndrome risk and interaction complexity.
CBD has its own interaction profile—no swap without medical review.
Use NutriAudit to audit your full stack for hidden overlaps.
Audit your supplement stackDisclaimer: NutriAudit is a decision-support tool designed to help you review your supplement stack for potential duplicate, conflicting, or excessive ingredients. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making changes to your supplement routine, especially if you are pregnant, nursing, taking medications, or have a medical condition.
Based on reference standards from FDA, EFSA, TGA, and MHLW.
Last updated: 2026-04-07 · Data sourced from FDA Dietary Reference Intakes, EFSA Scientific Opinions, and NIH Office of Dietary Supplements where applicable.