Mifepristone and Norethindrone interaction
Mifepristone and Norethindrone: 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 Mifepristone label · effective 2025-09-25
Hormonal contraceptives: Do not use with mifepristone ( 7.6 ).
…study has been conducted to evaluate the effect of mifepristone on substrates of CYP2B6, the concomitant use of bupropion and efavirenz should be undertaken with caution. [See Clinical Pharmacology ( 12.3 )] 7.6 Use of Hormonal Contraceptives Mifepristone is a progesterone-receptor antagonist and will interfere with the effectiveness of hormonal contraceptives.
Therefore, non-hormonal contraceptive methods should be used. [See Use In Specific Populations ( 8.3 )]
From the Norethindrone label · effective 2026-01-31
• Effects of Other Drugs on Hormonal Contraceptives Substances decreasing the systemic concentrations of hormonal contraceptives (HCs) and potentially diminishing the efficacy of HCs: Drugs or herbal products that induce certain enzymes, including cytochrome P450 3A4 (CYP3A4), may decrease the systemic concentrations of HCs and potentially diminish the effectiveness…
Substances increasing the systemic concentrations of HCs: Co-administration of certain HCs and strong or moderate CYP3A4 inhibitors such as itraconazole, voriconazole, fluconazole, grapefruit juice, or ketoconazole may increase the systemic concentrations of progestins, including norethindrone.
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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.