Drug interactions
Mifepristone + St john's wort
Severity: Major
Mifepristone and St john's wort: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
St John's wort induces CYP3A4 and can substantially lower mifepristone concentrations, which may reduce efficacy. This matters for both the abortifacient and the Cushing's syndrome indications.
What this interaction means in plain words
Mifepristone and St john's wort can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
St John's wort induces CYP3A4 (and P-gp) via PXR activation, increasing mifepristone clearance.
What to do
Avoid the combination and have the patient stop St John's wort before starting mifepristone. If it cannot be avoided, monitor clinical response closely.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Mifepristone
- Apixaban + Mifepristone Contraindicated
- Argatroban + Mifepristone Contraindicated
- Cisapride + Mifepristone Contraindicated
- Cortisone + Mifepristone Contraindicated
- Cyclosporin + Mifepristone Contraindicated
- Dabigatran etexilate + Mifepristone Contraindicated
Frequently asked questions
Can I take Mifepristone with St john's wort?
MediHelp rates the interaction as major. Mifepristone and St john's wort can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. St John's wort induces CYP3A4 and can substantially lower mifepristone concentrations, which may reduce efficacy. This matters for both the abortifacient and the Cushing's syndrome indications.
How serious is the interaction between Mifepristone and St john's wort?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and have the patient stop St John's wort before starting mifepristone. If it cannot be avoided, monitor clinical response closely.
What other medicines interact with Mifepristone?
MediHelp also lists interactions of Mifepristone with, for example, Apixaban, Argatroban, Cisapride. The full list is on the Mifepristone page.
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