Drug interactions
Ketoconazole + Posaconazole
Severity: Major
Ketoconazole 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 are azole antifungals with QT-prolonging potential, and combining them gives no meaningful added antifungal benefit while increasing the risk of arrhythmia and hepatotoxicity. Ketoconazole may also increase posaconazole exposure through inhibition of efflux transport and metabolism.
What this interaction means in plain words
Ketoconazole 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.
Ketoconazole belongs to Anti Fungals; Posaconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation with possible P-glycoprotein and CYP-mediated increase in exposure.
What to do
Avoid using two systemic azoles together. If one must be continued, monitor ECG, electrolytes and liver function.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Ketoconazole with Posaconazole?
MediHelp rates the interaction as major. Ketoconazole 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 are azole antifungals with QT-prolonging potential, and combining them gives no meaningful added antifungal benefit while increasing the risk of arrhythmia and hepatotoxicity. Ketoconazole may also increase posaconazole exposure through inhibition of efflux transport and metabolism.
How serious is the interaction between Ketoconazole 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 using two systemic azoles together. If one must be continued, monitor ECG, electrolytes and liver function.
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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