St. John's Wort
An herbal supplement, traditionally used for mood support, that is well documented to reduce the effectiveness of many prescription medications.
What it is
St. John's Wort (Hypericum perforatum) is an herbal supplement sold over the counter in the United States; it has no FDA drug approval. It has been studied and used, particularly in Europe, for depression-related symptoms. It is one of the most well-documented herb-drug interaction sources: NCCIH states that St. John's wort "can interact in dangerous, sometimes life-threatening ways with a variety of medicines" through inducing cytochrome P-450 liver enzymes and intestinal P-glycoprotein, which can speed up how quickly the body clears many other medications.
Known interaction categories
- Insufficient evidence
- Use caution
- Monitor
Published interaction pages on this site
Use caution (3)
Monitor (1)
Insufficient evidence (31)
- St. John's Wort and AmlodipineInsufficient evidence
- St. John's Wort and AshwagandhaInsufficient evidence
- St. John's Wort and AspirinInsufficient evidence
- St. John's Wort and CaffeineInsufficient evidence
- St. John's Wort and CalciumInsufficient evidence
- St. John's Wort and CiprofloxacinInsufficient evidence
- St. John's Wort and CopperInsufficient evidence
- St. John's Wort and CoQ10 (Coenzyme Q10)Insufficient evidence
- St. John's Wort and CreatineInsufficient evidence
- St. John's Wort and DoxycyclineInsufficient evidence
- St. John's Wort and Folate / Folic AcidInsufficient evidence
- St. John's Wort and IbuprofenInsufficient evidence
- St. John's Wort and IronInsufficient evidence
- St. John's Wort and LevothyroxineInsufficient evidence
- St. John's Wort and LisinoprilInsufficient evidence
- St. John's Wort and LosartanInsufficient evidence
- St. John's Wort and MagnesiumInsufficient evidence
- St. John's Wort and MelatoninInsufficient evidence
- St. John's Wort and MetforminInsufficient evidence
- St. John's Wort and Omega-3 / Fish OilInsufficient evidence
- St. John's Wort and OmeprazoleInsufficient evidence
- St. John's Wort and PotassiumInsufficient evidence
- St. John's Wort and ProbioticsInsufficient evidence
- St. John's Wort and SpironolactoneInsufficient evidence
- St. John's Wort and TurmericInsufficient evidence
- St. John's Wort and Vitamin B12Insufficient evidence
- St. John's Wort and Vitamin CInsufficient evidence
- St. John's Wort and Vitamin DInsufficient evidence
- St. John's Wort and Vitamin EInsufficient evidence
- St. John's Wort and Vitamin KInsufficient evidence
- St. John's Wort and ZincInsufficient evidence
Related guides
Sources
Last reviewed 2026-08-22
Medical information disclaimer: this information is general and educational. It does not diagnose conditions, prescribe treatment, or determine whether a combination is safe for you personally. Follow your prescription label and ask a pharmacist or clinician before starting, stopping, or combining products. Full disclaimer.