Drug interactions
Nirmatrelvir / ritonavir + Voriconazole
Severity: Major
Nirmatrelvir / ritonavir 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
Ritonavir can reduce voriconazole concentrations, risking loss of antifungal efficacy in patients with invasive fungal infection. Voriconazole may also increase exposure to nirmatrelvir and ritonavir.
What this interaction means in plain words
Nirmatrelvir / ritonavir 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.
Why it happens
Ritonavir induces CYP2C19 (and other enzymes) that metabolize voriconazole, while voriconazole inhibits CYP3A4 clearance of nirmatrelvir and ritonavir.
What to do
Avoid concurrent use when possible; if required, check voriconazole trough concentrations and adjust the dose, and monitor for treatment failure.
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
Frequently asked questions
Can I take Nirmatrelvir / ritonavir with Voriconazole?
MediHelp rates the interaction as major. Nirmatrelvir / ritonavir 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. Ritonavir can reduce voriconazole concentrations, risking loss of antifungal efficacy in patients with invasive fungal infection. Voriconazole may also increase exposure to nirmatrelvir and ritonavir.
How serious is the interaction between Nirmatrelvir / ritonavir 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 use when possible; if required, check voriconazole trough concentrations and adjust the dose, and monitor for treatment failure.
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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