Estradiol and norethindrone and Mifepristone interaction
Estradiol and norethindrone and Mifepristone: 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 Estradiol and norethindrone (Estradiol / Norethindrone Acetate) label · effective 2026-06-26
Therefore, the relevance of the WHI findings regarding adverse cardiovascular events, dementia and breast cancer to lower CE plus other MPA doses, other routes of administration, or other estrogen plus progestogen products is not known.
Inducers and/or inhibitors of CYP3A4 may affect estrogen drug metabolism and decrease or increase the estrogen plasma concentration.
Inhibitors of CYP3A4 such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice may increase plasma concentrations of estrogens and result in adverse reactions.
Therefore, inducers or inhibitors of CYP3A4 may affect estrogen drug metabolism.
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 )]
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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.