Drug interactions
Ketoconazole + Voriconazole
Severity: Major
Ketoconazole and Voriconazole: 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 azoles can prolong the QT interval, and each inhibits CYP3A4, so combined use raises arrhythmia and hepatotoxicity risk with no therapeutic advantage. Voriconazole and ketoconazole are rarely appropriate together.
What this interaction means in plain words
Ketoconazole and Voriconazole 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; Voriconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation and overlapping CYP inhibition, with additive hepatotoxic potential.
What to do
Avoid combining two systemic azoles; if unavoidable, monitor ECG, electrolytes and liver tests.
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 Voriconazole
- Avanafil + Voriconazole Contraindicated
- Butabarbital + Voriconazole Contraindicated
- Carbamazepine + Voriconazole Contraindicated
- Conivaptan + Voriconazole Contraindicated
- Dihydroergotamine intranasal + Voriconazole Contraindicated
- Dihydroergotamine + Voriconazole 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 Voriconazole?
MediHelp rates the interaction as major. Ketoconazole and Voriconazole 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 azoles can prolong the QT interval, and each inhibits CYP3A4, so combined use raises arrhythmia and hepatotoxicity risk with no therapeutic advantage. Voriconazole and ketoconazole are rarely appropriate together.
How serious is the interaction between Ketoconazole and Voriconazole?
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 combining two systemic azoles; if unavoidable, monitor ECG, electrolytes and liver tests.
What other medicines interact with Voriconazole?
MediHelp also lists interactions of Voriconazole with, for example, Avanafil, Butabarbital, Carbamazepine. The full list is on the Voriconazole page.
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