Drug Interaction Report

Mifepristone and Losartan: Interaction Details

A pharmacist-reviewed analysis of the Mifepristone and Losartan interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Mifepristone

Korlym Mifeprex
+

Losartan

Arbli Cozaar Cozaar®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
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.

Of 225 documented Mifepristone interactions, 17 are rated moderate — including this one.
Onset
unspecified
Evidence
theoretical
Severity
Moderate

What happens

Increased exposure to losartan

Interaction Deep Dive

Concomitant administration of losartan, a CYP2C9 substrate2, with mifepristone, a CYP2C9 inhibitor, may lead to increased exposure to losartan. Although not specifically studied with losartan, coadministration of a single 40 mg fluvastatin dose (a CYP2C8/2C9 substrate) in healthy subjects receiving mifepristone (Korlym(TM)) 1200 mg orally once daily led to significantly increased fluvastatin exposure, with geometric mean ratios (with/without coadministration) of fluvastatin AUC and Cmax of 3.57 and 1.76, respectively 1. Additionally, multiple-dose coadministration of fluconazole (a CYP2C9 inhibitor) decreased the exposure of losartan's active metabolite by 40% and increased the losartan exposure by approximately 70% 2. The lowest dose of losartan should be used when given concomitantly with mifepristone (Korlym(TM)) and patients should be monitored closely for losartan adverse effects. Due to the long terminal half-life of mifepristone after reaching steady state, allow at least 2 weeks following cessation of mifepristone (Korlym(TM)) before increasing the dose of losartan 1.

Why it happens (mechanism)

Inhibition of CYP2C9-mediated metabolism of losartan

Common questions

Can I take Mifepristone and Losartan together?

Increased exposure to losartan Always confirm with your pharmacist or prescriber before making any change.

How serious is the Mifepristone and Losartan interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Mifepristone or Losartan 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 anything you'd monitor while I'm on both?

References (2)

  1. Product Information: Korlym(TM) oral tablets, mifepristone oral tablets. Corcept Therapeutics (per manufacturer), Menlo Park, CA, 2012. DailyMed
  2. Product Information: COZAAR(R) oral tablets, losartan potassium oral tablets. Merck Sharp & Dohme Corp. (per FDA), Whitehouse Station, NJ, 2011. DailyMed
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Mifepristone

Keep reading about Mifepristone

All Mifepristone interactions (225)
Also serious with: Diflorasone Topical Clindamycin Topical Desonide Hydrocortisone
Losartan

Keep reading about Losartan

All Losartan interactions (146) Losartan drug information
Also serious with: Aliskiren Sparsentan Lisinopril Voriconazole
Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Mifepristone + Activated Charcoal American Hellebore Arsenic Cesium Ephedra Grapefruit Sida Cordifolia St. John's Wort + 143 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.