Drug interactions
Efavirenz + Ivacaftor
Severity: Major
Efavirenz and 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
Efavirenz can lower ivacaftor concentrations enough to reduce CFTR potentiation and clinical efficacy. Ivacaftor is a weak CYP3A inhibitor and may modestly raise efavirenz exposure, but the induction effect on ivacaftor is the main concern.
What this interaction means in plain words
Efavirenz and 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.
Efavirenz belongs to Anti Virals; Ivacaftor belongs to Miscellaneous.
Why it happens
Efavirenz induces CYP3A4, accelerating ivacaftor metabolism; ivacaftor weakly inhibits CYP3A.
What to do
Avoid combining ivacaftor with strong CYP3A inducers where possible and consider an alternative antiretroviral. Monitor respiratory status and CF response if used together.
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 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
Other interactions of Ivacaftor
- Ensitrelvir + Ivacaftor Contraindicated
- Apalutamide + Ivacaftor Major
- Carbamazepine + Ivacaftor Major
- Clarithromycin + Ivacaftor Major
- Enzalutamide + Ivacaftor Major
- Ivacaftor + Oxcarbazepine Major
Frequently asked questions
Can I take Efavirenz with Ivacaftor?
MediHelp rates the interaction as major. Efavirenz and 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. Efavirenz can lower ivacaftor concentrations enough to reduce CFTR potentiation and clinical efficacy. Ivacaftor is a weak CYP3A inhibitor and may modestly raise efavirenz exposure, but the induction effect on ivacaftor is the main concern.
How serious is the interaction between Efavirenz and 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 combining ivacaftor with strong CYP3A inducers where possible and consider an alternative antiretroviral. Monitor respiratory status and CF response if used together.
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.
