Drug interactions
Ketoconazole + Mefloquine
Severity: Major
Ketoconazole 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
Ketoconazole increases mefloquine exposure and both drugs can prolong the QT interval. This raises the risk of serious arrhythmias and mefloquine neuropsychiatric toxicity.
What this interaction means in plain words
Ketoconazole 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.
Ketoconazole belongs to Anti Fungals; Mefloquine belongs to Anti Parasitic.
Why it happens
Additive QT prolongation plus CYP3A4 inhibition by ketoconazole reducing mefloquine clearance.
What to do
Avoid concurrent use and choose another antimalarial or antifungal. Mefloquine has a long half-life, so allow for prolonged overlap and obtain an ECG if exposure is unavoidable.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole 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 Ketoconazole with Mefloquine?
MediHelp rates the interaction as major. Ketoconazole 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. Ketoconazole increases mefloquine exposure and both drugs can prolong the QT interval. This raises the risk of serious arrhythmias and mefloquine neuropsychiatric toxicity.
How serious is the interaction between Ketoconazole 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: Avoid concurrent use and choose another antimalarial or antifungal. Mefloquine has a long half-life, so allow for prolonged overlap and obtain an ECG if exposure is unavoidable.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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