Drug interactions
Efavirenz + Mefloquine
Severity: Major
Efavirenz and Mefloquine: 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 may lower mefloquine concentrations, reducing antimalarial efficacy, and both drugs can prolong the QT interval. Neuropsychiatric effects may also be additive.
What this interaction means in plain words
Efavirenz and Mefloquine 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; Mefloquine belongs to Anti Parasitic.
Why it happens
CYP3A4 induction increases mefloquine clearance, plus additive QT prolongation and CNS effects.
What to do
Consider an alternative antimalarial. If used, obtain an ECG and monitor for neuropsychiatric effects and treatment failure.
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 Mefloquine
- Arsenic trioxide + Mefloquine Contraindicated
- Dronedarone + Mefloquine Contraindicated
- Ibutilide + Mefloquine Contraindicated
- Levoketoconazole + Mefloquine Contraindicated
- Mefloquine + Nilotinib Contraindicated
- Mefloquine + Pimozide Contraindicated
Frequently asked questions
Can I take Efavirenz with Mefloquine?
MediHelp rates the interaction as major. Efavirenz and Mefloquine 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 may lower mefloquine concentrations, reducing antimalarial efficacy, and both drugs can prolong the QT interval. Neuropsychiatric effects may also be additive.
How serious is the interaction between Efavirenz and Mefloquine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider an alternative antimalarial. If used, obtain an ECG and monitor for neuropsychiatric effects and treatment failure.
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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