Nirmatrelvir and ritonavir and Vincristine interaction
Nirmatrelvir and ritonavir and Vincristine: 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
Anticancer drugs abemaciclib, ceritinib, dasatinib, encorafenib, ibrutinib, ivosidenib, neratinib, nilotinib, venetoclax, vinblastine, vincristine ↑ anticancer drugs Avoid co-administration of encorafenib or ivosidenib due to potential risk of serious adverse events such as QT interval prolongation.
Co-administration of vincristine and vinblastine may lead to significant hematologic or gastrointestinal side effects.
From the Vincristine (VinCRIStine Sulfate) label · effective 2026-02-17
Therefore, the concomitant use of strong CYP3A inhibitors with vincristine sulfate should be avoided.
Therefore, the concomitant use of P-gp inhibitors or inducers should be avoided.
Patients should be frequently monitored for adverse reactions with concomitant use of moderate CYP3A inhibitors (e.g., fluconazole) with vincristine sulfate.
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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.