Omeprazole and Mifepristone: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mifepristone
Omeprazole
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.
Here's what's going on: Mifepristone can slow down one of your body's liver enzymes (called CYP3A4). Omeprazole, your acid-reducing medicine, is partly broken down by that same enzyme. So when you take them together, omeprazole may not clear as quickly and its levels can build up a bit higher than usual.
The good news is this concern is based mostly on theory, not on lots of real-world problems. Your care team can handle it easily by using the lowest helpful dose and keeping an eye on how you feel. Please don't stop or change either medicine on your own. Just check in with your pharmacist or doctor so they can make sure the combination is right for you.
Mechanism: Mifepristone is a strong CYP3A4 inhibitor. Omeprazole is a CYP3A4 (and CYP2C19) substrate, so coadministration may reduce its first-pass and systemic metabolism, increasing omeprazole exposure (AUC/Cmax).
- Direction: increased CYP3A4 substrate (omeprazole) exposure
- Evidence: theoretical; magnitude not quantified
- Onset: unspecified
- Severity: major (per database)
Management: Use the lowest effective dose and/or reduced frequency of the CYP3A4 substrate with clinical monitoring for exaggerated effects. Prefer an agent without high CYP3A4-dependent first-pass metabolism when feasible. Allow at least 2 weeks after stopping mifepristone before initiating affected CYP3A4 substrates.
What happens
Increased CYP3A4 substrate exposure
Interaction Deep Dive
Because miFEPRIStone acts as a potent inhibitor of CYP3A4, exercise extreme caution whenever it is given together with agents that undergo extensive first pass metabolism through CYP3A4. Apply the lowest possible dose and/or a decreased dosing frequency alongside therapeutic monitoring. Where feasible, choose alternative agents that lack these metabolic properties. Furthermore, allow a minimum of 2 weeks following discontinuation of miFEPRIStone before starting CYP3A4 substrates1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by miFEPRIStone
How to manage this interaction
Keep taking both medicines as prescribed unless your care team tells you otherwise. Because mifepristone can raise omeprazole levels, here is how a care team typically handles it:
- Use the lowest effective dose and/or a reduced frequency of the affected medicine.
- Monitor you more closely for stronger-than-usual effects; your dose may be adjusted and individualized by your team.
- Consider an alternative acid-reducing medicine that isn't as dependent on this enzyme, if appropriate.
- If mifepristone is stopped, your team may wait about 2 weeks before starting affected medicines.
What to do: Ask your pharmacist or prescriber to review this combination and mention any new or unusual symptoms.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Omeprazole and Mifepristone together?
Mifepristone can raise omeprazole levels by blocking the enzyme that clears it, so your care team may use the lowest dose and watch you more closely; keep taking both as prescribed and check in with your pharmacist. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Mifepristone interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Omeprazole and Mifepristone interaction managed?
Keep taking both medicines as prescribed unless your care team tells you otherwise. Because mifepristone can raise omeprazole levels, here is how a care team typically handles it: Use the lowest effective dose and/or a reduced frequency of the affected medicine. Monitor you more closely for stronger-than-usual effects; your dose may be adjusted and individualized by your team. Consider an alternat… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Omeprazole 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 (1)
- 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 Omeprazole
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:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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