Ketoconazole Topical and Mifepristone: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mifepristone
Ketoconazole Topical
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased miFEPRIStone exposure, increased ketoconazole exposure, an increased risk of ketoconazole-related adverse reactions and an increased risk for QT interval prolongation
Interaction Deep Dive
Concomitant use of ketoconazole (CYP3A inhibitor and substrate) with a CYP3A4 substrate and inhibitor known to prolong the QT interval, such as miFEPRIStone is contraindicated, as this may increase miFEPRIStone and/or ketoconazole exposure, increasing the risk for QT prolongation and life-threatening ventricular tachyarrhythmias including torsades de pointes1. Use the lowest dose and/or decreased frequency with therapeutic monitoring. Prefer alternative drugs without these metabolic characteristics when possible. When concomitant use is required, limit the miFEPRIStone dose to 900 mg/day. Consider using the lowest ketoconazole dose necessary, and monitor and follow up as appropriate. Start miFEPRIStone at a dose of 300 mg to patients already being treated with ketoconazole (strong CYP3A inhibitor). If clinically indicated, titrate to a maximum of 900 mg. Dose adjustment of miFEPRIStone when ketoconazole is added in patients already being treated with miFEPRIStone; if current dose of miFEPRIStone is 300 mg, no change required. If current dose of miFEPRIStone is 600 mg, reduce dose to 300 mg. If clinically indicated, titrate to a maximum of 600 mg. If current dose of miFEPRIStone is 900 mg, reduce dose to 600 mg. If clinically indicated, titrate to a maximum of 900 mg. If current dose of miFEPRIStone is 1200 mg, reduce dose to 900 mg. Wait at least 2 weeks after stopping miFEPRIStone before increasing ketoconazole 2.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of miFEPRIStone; inhibition of CYP3A4-mediated metabolism of ketoconazole; increased risk for QT interval prolongation
Literature reports
2 reports — tap to read
a) In a drug interaction study, coadministration of miFEPRIStone, 600 mg once daily for 17 days and ketoconazole, 200 mg bid on days 13 to 17 resulted in increased miFEPRIStone AUC and Cmax by 1.38-fold and 1.28-fold, respectively 2.
b) In a drug interaction study, coadministration of miFEPRIStone 1200 mg once daily for 10 days and simvastatin (CYP3A4 substrate) 80 mg single dose, resulted in increased simvastatin AUC and Cmax by 10.40-fold and 7.02-fold, respectively. Also resulted in increased simvastatin acid AUC and Cmax by 15.7-fold and 18.20, respectively 2.
Common questions
Can I take Ketoconazole Topical and Mifepristone together?
Increased miFEPRIStone exposure, increased ketoconazole exposure, an increased risk of ketoconazole-related adverse reactions and an increased risk for QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ketoconazole Topical and Mifepristone interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Ketoconazole Topical or Mifepristone need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: Ketoconazole oral tablet, ketoconazole oral tablet. Taro Pharmaceuticals U.S.A. Inc. (per DailyMed), Hawthorne, NY, 2024. DailyMed
- Product Information: KORLYM(R) oral tablets, mifepristone oral tablets. Corcept Therapeutics Incorporated (per Dailmed), Redwood City, CA, 2024. DailyMed
Keep reading about Mifepristone
Keep reading about Ketoconazole Topical
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