Drug interactions
Efavirenz + Lumacaftor / ivacaftor
Severity: Major
Efavirenz and Lumacaftor / ivacaftor: 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
Lumacaftor is itself a strong CYP3A inducer and ivacaftor is a CYP3A substrate, so adding efavirenz offers little benefit and can further lower ivacaftor exposure. Lumacaftor may also reduce efavirenz concentrations.
What this interaction means in plain words
Efavirenz and Lumacaftor / ivacaftor 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
Mutual CYP3A induction reduces ivacaftor and potentially efavirenz exposure.
What to do
Avoid concurrent use if possible and monitor CFTR response and HIV viral load if both are required.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Efavirenz and Lumacaftor / ivacaftor, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
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 Lumacaftor / ivacaftor?
MediHelp rates the interaction as major. Efavirenz and Lumacaftor / ivacaftor 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. Lumacaftor is itself a strong CYP3A inducer and ivacaftor is a CYP3A substrate, so adding efavirenz offers little benefit and can further lower ivacaftor exposure. Lumacaftor may also reduce efavirenz concentrations.
How serious is the interaction between Efavirenz and Lumacaftor / ivacaftor?
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 concurrent use if possible and monitor CFTR response and HIV viral load if both are required.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
