Omeprazole and Rifampin: 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
Rifampin
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.
What's going on: Rifampin (Rifadin) speeds up the liver's ability to break down omeprazole (Prilosec). When you take them together, your body clears the omeprazole faster, so there may be less of it in your blood to do its job.
Omeprazole is used to lower stomach acid and help with things like heartburn or an ulcer. If it's being cleared too fast, you might notice your acid symptoms coming back or not being as well controlled. The good news is that your care team can watch for this and adjust your treatment if needed. Please talk with your pharmacist or doctor before changing anything on your own.
Effect: Reduced omeprazole exposure when co-administered with rifampin.
Mechanism: Rifampin induces CYP2C19 and CYP3A4, the primary enzymes metabolizing omeprazole, increasing its clearance and substantially lowering plasma concentrations (reduced AUC/Cmax). Omeprazole is an active drug (not a prodrug), so lower exposure means reduced acid-suppressant efficacy.
- Direction: Decreased omeprazole effect (potential treatment failure).
- Onset: Unspecified; enzyme induction typically develops over days.
- Evidence: Theoretical.
- Management: Combination should be avoided per label. If unavoidable, monitor clinical response and consider individualized therapy adjustment.
What happens
Reduced omeprazole exposure
Interaction Deep Dive
CYP2C19 and CYP3A4 are the primary enzymes responsible for the extensive metabolism of omeprazole. Because rifampin induces both CYP2C19 and CYP3A4, taking it together with omeprazole may markedly lower omeprazole plasma levels, and this combination should therefore be avoided123.
Why it happens (mechanism)
Induction of CYP2C19-mediated metabolism of omeprazole by rifampin; induction of CYP3A-mediated metabolism of omeprazole by rifampin
How to manage this interaction
What your care team may do:
- The documented guidance is that this combination is generally best avoided, so your prescriber may choose a different acid-reducing option or a different plan.
- If both are needed, your team may monitor your symptoms more closely and tailor your therapy to keep your stomach acid controlled.
What you can do: Keep taking both medicines exactly as prescribed for now. Let your pharmacist or doctor know if your heartburn, reflux, or stomach symptoms return or worsen. Do not stop or change either medication on your own.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) While no formal drug-interaction studies have been performed with rifampin, a crossover study evaluated the concurrent administration of St John's wort (another CYP3A4 inducer) 300 mg three times daily for 14 days together with omeprazole in 12 healthy male subjects. In CYP2C19 poor metabolizers, omeprazole Cmax and AUC fell by 37.5% and 37.9%, respectively, while in extensive metabolizers they fell by 49.6% and 43.9%, respectively 23.
Common questions
Can I take Omeprazole and Rifampin together?
Rifampin can make omeprazole clear from your body faster and work less well, so this combination is usually avoided; tell your doctor or pharmacist if your acid symptoms return. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Rifampin 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 Rifampin interaction managed?
What your care team may do: The documented guidance is that this combination is generally best avoided, so your prescriber may choose a different acid-reducing option or a different plan. If both are needed, your team may monitor your symptoms more closely and tailor your therapy to keep your stomach acid controlled. What you can do: Keep taking both medicines exactly as prescribed for now. Let yo… 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 Rifampin 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 (3)
- Product Information: KONVOMEP(TM) powder for oral suspension, omeprazole sodium bicarbonate powder for oral suspension. Azurity Pharmaceuticals Inc (per manufacturer), Woburn, MA, 2022. DailyMed
- Product Information: PRILOSEC(R) oral delayed-release capsules, omeprazole oral delayed-release capsules. AstraZeneca Pharmaceuticals LP (Per FDA), Wilmington, DE, 2011. DailyMed
- Product Information: PRILOSEC(R) delayed-release oral suspension, omeprazole magnesium delayed-release oral suspension. AstraZeneca Pharmaceuticals LP (Per FDA), Wilmington, DE, 2011. DailyMed
Keep reading about Rifampin
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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