Drug interactions
Mefloquine + Posaconazole
Severity: Major
Mefloquine and Posaconazole: 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
Both drugs can prolong the QT interval, and posaconazole may also raise mefloquine concentrations. Together this increases the risk of torsades de pointes and mefloquine neuropsychiatric toxicity.
What this interaction means in plain words
Mefloquine and Posaconazole 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.
Mefloquine belongs to Anti Parasitic; Posaconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation, plus CYP3A4 inhibition by posaconazole reducing mefloquine clearance.
What to do
Avoid the combination where possible and choose another antimalarial or antifungal. If unavoidable, obtain a baseline ECG, correct potassium and magnesium, and monitor the QTc; mefloquine's long half-life means the interaction persists after it is stopped.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole 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 Mefloquine with Posaconazole?
MediHelp rates the interaction as major. Mefloquine and Posaconazole 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. Both drugs can prolong the QT interval, and posaconazole may also raise mefloquine concentrations. Together this increases the risk of torsades de pointes and mefloquine neuropsychiatric toxicity.
How serious is the interaction between Mefloquine and Posaconazole?
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 the combination where possible and choose another antimalarial or antifungal. If unavoidable, obtain a baseline ECG, correct potassium and magnesium, and monitor the QTc; mefloquine's long half-life means the interaction persists after it is stopped.
What other medicines interact with Posaconazole?
MediHelp also lists interactions of Posaconazole with, for example, Artemether, Avanafil, Cobimetinib. The full list is on the Posaconazole page.
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