Drug interactions
Efavirenz + Mifepristone
Severity: Major
Efavirenz and Mifepristone: major interaction.
Last updated
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
Mifepristone is metabolized by CYP3A4, and efavirenz may reduce its exposure and effectiveness. Mifepristone at higher chronic doses can prolong the QT interval, adding to efavirenz's effect.
What this interaction means in plain words
Efavirenz and Mifepristone 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.
Efavirenz belongs to Anti Virals; Mifepristone belongs to Endocrine.
Why it happens
CYP3A4 induction by efavirenz lowers mifepristone levels, plus additive QT prolongation.
What to do
Avoid if possible. If used, monitor ECG and electrolytes and confirm the desired clinical effect of mifepristone, for example completed pregnancy termination.
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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Other interactions of Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
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 Efavirenz with Mifepristone?
MediHelp rates the interaction as major. Efavirenz and Mifepristone 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. Mifepristone is metabolized by CYP3A4, and efavirenz may reduce its exposure and effectiveness. Mifepristone at higher chronic doses can prolong the QT interval, adding to efavirenz's effect.
How serious is the interaction between Efavirenz and Mifepristone?
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 if possible. If used, monitor ECG and electrolytes and confirm the desired clinical effect of mifepristone, for example completed pregnancy termination.
What other medicines interact with Efavirenz?
MediHelp also lists interactions of Efavirenz with, for example, Cobimetinib, Dienogest / estradiol valerate, Dihydroergotamine intranasal. The full list is on the Efavirenz page.
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