Drug interactions
Efavirenz + Rifampin
Severity: Moderate
Efavirenz and Rifampin: moderate 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
Rifampin induces CYP2B6 and CYP3A4 and lowers efavirenz concentrations, which may risk virologic failure. Efavirenz is nevertheless commonly used with rifampin-based TB therapy.
What this interaction means in plain words
Efavirenz and Rifampin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Rifampin induces CYP2B6 and CYP3A4, increasing efavirenz clearance.
What to do
Use the standard 600 mg efavirenz dose per current guidelines. Monitor HIV viral load and consider therapeutic drug monitoring where available.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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
Frequently asked questions
Can I take Efavirenz with Rifampin?
MediHelp rates the interaction as moderate. Efavirenz and Rifampin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Rifampin induces CYP2B6 and CYP3A4 and lowers efavirenz concentrations, which may risk virologic failure. Efavirenz is nevertheless commonly used with rifampin-based TB therapy.
How serious is the interaction between Efavirenz and Rifampin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use the standard 600 mg efavirenz dose per current guidelines. Monitor HIV viral load and consider therapeutic drug monitoring where available.
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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