Nirmatrelvir and ritonavir and Voriconazole interaction
Nirmatrelvir and ritonavir and Voriconazole: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Nirmatrelvir and ritonavir (Paxlovid) label · effective 2026-02-19
Antifungals voriconazole ↓ voriconazole Avoid concomitant use of voriconazole. ketoconazole, isavuconazonium sulfate, itraconazole ↑ ketoconazole ↑ isavuconazonium sulfate ↑ itraconazole Refer to the ketoconazole, isavuconazonium sulfate, and itraconazole prescribing information for further information. ↑ nirmatrelvir/ritonavir A nirmatrelvir/ritonavir dose reduction…
From the Voriconazole label · effective 2026-06-02
• Long-acting barbiturates • Rifabutin • Rifampin • Ritonavir Concomitant use with high-dose ritonavir (400 mg every 12 hours) is contraindicated.
Concomitant use with low-dose ritonavir (100 mg every 12 hours) should be avoided, unless an assessment of the benefit/risk to the patient justifies the use of voriconazole [see Clinical Pharmacology (12.3) ] .
High-dose Ritonavir (400 mg every 12 hours) (CYP450 Induction) Significantly Reduced Contraindicated Low-dose Ritonavir (100 mg every 12 hours) (CYP450 Induction) Reduced Concomitant administration of voriconazole and low-dose ritonavir (100 mg every 12 hours) should be avoided, unless an assessment of the benefit/risk to the patient justifies the use of voriconazole.
Low-dose Ritonavir (100 mg every 12 hours) Slight Decrease in Ritonavir C max and AUC τ Concomitant administration of voriconazole and low-dose ritonavir (100 mg every 12 hours) should be avoided (due to the reduction in voriconazole C max and AUC τ ) unless an assessment of the benefit/risk to the patient justifies the use of voriconazole.
High-dose Ritonavir (400 mg every 12 hours) (CYP3A4 Inhibition) No Significant Effect of Voriconazole on Ritonavir C max or AUC τ Contraindicated because of significant reduction of voriconazole C max and AUC τ .
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.