Drug Interaction Report

Mifepristone and Fentanyl Transdermal Patch: Interaction Details

A pharmacist-reviewed analysis of the Mifepristone and Fentanyl Transdermal Patch 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
+

Fentanyl Transdermal Patch

Duragesic®
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
Contraindicated
These should generally not be used together.
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, 69 are rated contraindicated — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
theoretical
Severity
Contraindicated

What happens

Increased fentaNYL exposure and risk of adverse events

Interaction Deep Dive

Coadministration of miFEPRIStone (strong CYP3A4 inhibitor) (Korlym®) and fentaNYL (CYP3A4 substrates with NTI) is contraindicated as it may increase fentaNYL exposure. If coadministered, discontinuation or dose reduction of fentaNYL may be necessary1. However, exert caution when miFEPRIStone (Mifeprex®) is coadministered with fentaNYL. Due to the slow elimination of miFEPRIStone from the body, such interaction may be observed for a prolonged period after its administration 2. Based on the long terminal half-life of miFEPRIStone after reaching steady state, elapse at least 2 weeks after cessation of miFEPRIStone before initiating fentaNYL 1.

Why it happens (mechanism)

Inhibition of CYP3A4-mediated metabolism of fentaNYL

Common questions

Can I take Mifepristone and Fentanyl Transdermal Patch together?

Increased fentaNYL exposure and risk of adverse events Always confirm with your pharmacist or prescriber before making any change.

How serious is the Mifepristone and Fentanyl Transdermal Patch 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Mifepristone or Fentanyl Transdermal Patch 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)

  1. Product Information: KORLYM(R) oral tablets, mifepristone oral tablets. Corcept Therapeutics Incorporated (per Dailmed), Redwood City, CA, 2024. DailyMed
  2. Product Information: MIFEPREX(R) oral tablets, mifepristone oral tablets. Danco Laboratories, LLC (per FDA), New York, NY, 2023. DailyMed
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Mifepristone

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Fentanyl Transdermal Patch

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All Fentanyl Transdermal Patch interactions (493) Fentanyl Transdermal Patch drug information
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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.