Drug interactions
Efavirenz + Flecainide
Severity: Major
Efavirenz and Flecainide: 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
Flecainide has a narrow therapeutic index and proarrhythmic effects, and efavirenz can prolong QT, so together they may raise the risk of serious ventricular arrhythmia. Efavirenz may also alter flecainide levels through enzyme effects.
What this interaction means in plain words
Efavirenz and Flecainide 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; Flecainide belongs to Cardiovascular.
Why it happens
Additive effects on cardiac conduction and repolarization, with possible pharmacokinetic changes via CYP induction.
What to do
Avoid if possible and select a different antiretroviral. If used, monitor ECG and flecainide plasma concentrations.
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 Flecainide
- Flecainide + Nirmatrelvir Contraindicated
- Flecainide + Nirmatrelvir / ritonavir Contraindicated
- Flecainide + Pimozide Contraindicated
- Flecainide + Ritonavir Contraindicated
- Flecainide + Thioridazine Contraindicated
- Flecainide + Tipranavir Contraindicated
Frequently asked questions
Can I take Efavirenz with Flecainide?
MediHelp rates the interaction as major. Efavirenz and Flecainide 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. Flecainide has a narrow therapeutic index and proarrhythmic effects, and efavirenz can prolong QT, so together they may raise the risk of serious ventricular arrhythmia. Efavirenz may also alter flecainide levels through enzyme effects.
How serious is the interaction between Efavirenz and Flecainide?
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 and select a different antiretroviral. If used, monitor ECG and flecainide plasma concentrations.
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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