Mifepristone and Prednisone interaction
Mifepristone and Prednisone: 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
WARNING: TERMINATION OF PREGNANCY Mifepristone is a potent antagonist of progesterone and cortisol via the progesterone and glucocorticoid (GR-II) receptors, respectively.
…ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus, due to an increased risk of adverse events. [See Drug Interactions ( 7.1 ) and Clinical Pharmacology ( 12.3 )] Patients receiving systemic corticosteroids for lifesaving purposes (e.g., immunosuppression after organ transplantation) because mifepristone antagonizes the effect of glucocorticoids.
Patients receiving systemic corticosteroids for lifesaving purposes ( 4 )
For medical conditions in which chronic corticosteroid therapy is lifesaving (e.g., immunosuppression in organ transplantation), 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,…
High doses of supplemental glucocorticoids may be needed to overcome the glucocorticoid receptor blockade produced by mifepristone.
From the Prednisone (Prednisone delayed release) label · effective 2026-04-30
CYP 3A4 Inhibitors (e.g., Ketoconazole, Macrolide Antibiotics) Ketoconazole has been reported to decrease the metabolism of certain corticosteroids by up to 60% leading to increased risk of corticosteroid side effects.
Estrogens, Including Oral Contraceptives Estrogens may decrease the hepatic metabolism of certain corticosteroids, thereby increasing their effect.
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.