St John's Wort … Safety & Interactions
Guan Ye Lian Qiao · Herba Hyperici Perforati
St John's Wort has a high overall interaction risk. It can lower the effectiveness of transplant medicines, oral contraceptives, antiretrovirals, warfarin, digoxin, benzodiazepines, and many other drugs, while combining it with serotonergic medicine can raise the risk of serotonin toxicity.
Contraindicated / High risk. Use only under qualified healthcare supervision.
Contraindications
- Concomitant use with medicines where reduced drug exposure or serotonergic toxicity would be dangerous
- Bipolar-spectrum mood instability without supervision
- Pregnancy
Cautions
- Memorial Sloan Kettering and major pharmacology reviews warn that St John's Wort can reduce effectiveness of oral contraceptives, transplant drugs, HIV drugs, anticoagulants, and many other medicines through enzyme and transporter induction.
- Photosensitivity and agitation are possible, especially at higher doses or in susceptible patients.
- The herb should not be treated as a casual wellness supplement when complex medication regimens are present.
Drug Interactions
| Drug Class / Substrate | Mechanism | Severity | Source |
|---|---|---|---|
| SSRIs, SNRIs, MAO inhibitors, triptans, and other serotonergic medicines | Additive serotonergic effects can produce potentially dangerous serotonin toxicity. | Major | NCCIH Herb-Drug Interactions |
| Cyclosporine, tacrolimus, and other transplant immunosuppressants | CYP enzyme and P-glycoprotein induction can reduce drug exposure and create a treatment-failure risk. | Major | NCCIH Herb-Drug Interactions |
| Oral contraceptives | Enzyme induction can reduce hormone exposure and contraceptive reliability. | Major | NCCIH Herb-Drug Interactions |
| Antiretroviral medicines | Clinically significant reductions in exposure have been documented with medicines including indinavir. | Major | NCCIH Herb-Drug Interactions |
| Warfarin, digoxin, benzodiazepines, and other CYP or P-glycoprotein substrates | Strong enzyme and transporter induction can reduce drug concentrations and therapeutic effect. | Major | NCCIH Herb-Drug Interactions |
Pregnancy
Not recommended during pregnancy. Consult a qualified healthcare provider before any use.
This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before using herbal medicines, especially if you take prescription medications.