Omeprazole and Atazanavir: 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
Atazanavir
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.
Atazanavir (Reyataz) is an HIV medicine that only dissolves and gets absorbed well when your stomach is acidic. Omeprazole (Prilosec) works by lowering stomach acid, and this raises the pH so much that your body absorbs far less of the atazanavir. In studies, the amount of atazanavir in the blood dropped by more than 90 percent. That's a big deal, because if your HIV medicine drops too low, it can stop working and the virus can become resistant to it.
The good news is your care team knows about this and can manage it. Please don't stop either drug on your own. Talk with your pharmacist or doctor so they can find the safest plan for you.
Effect: Substantially reduced atazanavir exposure with potential loss of virologic control and emergence of HIV resistance.
Mechanism: Atazanavir is a weak base with pH-dependent solubility. Omeprazole-induced gastric acid suppression raises intragastric pH, markedly reducing atazanavir dissolution and absorption.
- Magnitude: Atazanavir AUC decreased ~94%, Cmax ~96%, Cmin ~95% (omeprazole 40 mg).
- Evidence: Documented as theoretical/PK-based; severity major.
- Management: Coadministration not recommended, especially in treatment-experienced patients. If required in treatment-naive patients, limit PPI to
What happens
Reduced atazanavir exposure, reduced efficacy of atazanavir and development of resistance
Interaction Deep Dive
Taking atazanavir together with a PPI can markedly reduce atazanavir exposure, which may cause a loss of the drug's effectiveness and promote HIV resistance. In a study where repeated doses of atazanavir 400 mg once daily were combined with omeprazole 40 mg once daily (dosed 2 hours ahead of atazanavir), the atazanavir AUC fell by 94%, Cmax by 96%, and Cmin by 95%17. For this reason, giving the two drugs together is advised against, particularly in patients who are treatment-experienced. When such combined use cannot be avoided in treatment-naive patients, the PPI dose should not exceed the equivalent of omeprazole 20 mg, and it should be given 12 hours before atazanavir7.
Why it happens (mechanism)
Atazanavir solubility reduced by increased pH
How to manage this interaction
This combination can lower your HIV medicine to levels that may not control the virus, so your care team takes it seriously.
- Keep taking both exactly as prescribed and do not stop or change either drug on your own.
- Your team may avoid using them together, especially if you have taken HIV medicines before.
- If a PPI is truly needed and you are new to treatment, they typically keep the PPI dose at or below omeprazole 20 mg and separate the timing (PPI about 12 hours before atazanavir).
- Your dose may be adjusted and individualized, and your team may monitor your viral load more closely.
Ask your pharmacist or prescriber before starting any acid reducer, including over-the-counter ones.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
Common questions
Can I take Omeprazole and Atazanavir together?
Omeprazole can cut atazanavir absorption by more than 90 percent, risking HIV treatment failure and resistance, so this pairing is generally avoided. Never start or stop either drug on your own; check with your pharmacist or doctor first. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Atazanavir 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 Atazanavir interaction managed?
This combination can lower your HIV medicine to levels that may not control the virus, so your care team takes it seriously. Keep taking both exactly as prescribed and do not stop or change either drug on your own. Your team may avoid using them together, especially if you have taken HIV medicines before. If a PPI is truly needed and you are new to treatment, they typically keep the PPI dose at or… 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 Atazanavir 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 (7)
- 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: DEXILANT(TM) oral delayed-release capsules, dexlansoprazole oral delayed-release capsules. Takeda Pharmaceuticals America, Inc. (per FDA), Deerfield, IL, 2014. DailyMed
- Product Information: NEXIUM(R) oral delayed-release capsules, suspension, esomeprazole magnesium oral delayed-release capsules, suspension. AstraZeneca LP (per FDA), Wilmington, DE, 2014. DailyMed
- Product Information: esomeprazole strontium oral delayed-release capsules, esomeprazole strontium oral delayed-release capsules. Amneal Pharmaceuticals (per FDA), Glasgow, KY, 2014. DailyMed
- Product Information: PRILOSEC oral delayed-release suspension, omeprazole magnesium oral delayed-release suspension. AstraZeneca LP (per FDA), Wilmington, DE, 2014. DailyMed
- Product Information: PROTONIX(R) I.V. intravenous injection, pantoprazole sodium intravenous injection. Wyeth Pharmaceuticals (per FDA), Philadelphia, PA, 2014. DailyMed
- Product Information: REYATAZ(R) oral capsules, oral powder, atazanavir oral capsules, oral powder. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2023. DailyMed
Keep reading about Atazanavir
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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