Drug interactions
Fluconazole + Voriconazole
Severity: Major
Fluconazole and Voriconazole: major interaction.
Last updated Sources: US FDA label
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 azole antifungals can prolong the QT interval, so using them together increases the risk of torsades de pointes. Fluconazole also inhibits CYP3A4 and CYP2C19, which may raise voriconazole exposure. Combining two systemic azoles seldom has a therapeutic rationale.
What this interaction means in plain words
Fluconazole 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.
Fluconazole belongs to Anti Fungals; Voriconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation and fluconazole inhibition of voriconazole metabolism via CYP2C19/CYP3A4.
What to do
Avoid concurrent systemic use where possible. If unavoidable, monitor ECG, potassium and magnesium, and voriconazole-related toxicity.
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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References
Other interactions of Fluconazole
- Dihydroergotamine intranasal + Fluconazole Contraindicated
- Dihydroergotamine + Fluconazole Contraindicated
- Dofetilide + Fluconazole Contraindicated
- Domperidone + Fluconazole Contraindicated
- Dronedarone + Fluconazole Contraindicated
- Erythromycin + Fluconazole Contraindicated
Other interactions of Voriconazole
- Avanafil + Voriconazole Contraindicated
- Butabarbital + Voriconazole Contraindicated
- Carbamazepine + Voriconazole Contraindicated
- Conivaptan + Voriconazole Contraindicated
- Dihydroergotamine intranasal + Voriconazole Contraindicated
- Dihydroergotamine + Voriconazole Contraindicated
Frequently asked questions
Can I take Fluconazole with Voriconazole?
MediHelp rates the interaction as major. Fluconazole 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 azole antifungals can prolong the QT interval, so using them together increases the risk of torsades de pointes. Fluconazole also inhibits CYP3A4 and CYP2C19, which may raise voriconazole exposure. Combining two systemic azoles seldom has a therapeutic rationale.
How serious is the interaction between Fluconazole 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 concurrent systemic use where possible. If unavoidable, monitor ECG, potassium and magnesium, and voriconazole-related toxicity.
What other medicines interact with Fluconazole?
MediHelp also lists interactions of Fluconazole with, for example, Dihydroergotamine intranasal, Dihydroergotamine, Dofetilide. The full list is on the Fluconazole page.
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