Mifepristone and Nirmatrelvir and ritonavir interaction
Mifepristone and Nirmatrelvir and ritonavir: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Nirmatrelvir and ritonavir (Paxlovid) label · effective 2026-02-19
Hormonal contraceptive ethinyl estradiol ↓ ethinyl estradiol An additional, non-hormonal method of contraception should be considered during the 5 days of PAXLOVID treatment and until one menstrual cycle after stopping PAXLOVID.
From the Mifepristone label · effective 2025-09-25
…mifepristone is contraindicated. [See Contraindications (4.3)] 5.6 Use of Strong CYP3A Inhibitors Mifepristone should be used with caution in patients taking ketoconazole and other strong inhibitors of CYP3A, such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir, fosamprenavir, clarithromycin, conivaptan, lopinavir/ritonavir, posaconazole,…
Ketoconazole and other strong inhibitors of CYP3A, such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir and fosamprenavir, clarithromycin, conivaptan, lopinavir /ritonavir, posaconazole, saquinavir, telithromycin, or voriconazole may increase exposure to mifepristone.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
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.