Omeprazole and Olanzapine: 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
Olanzapine
No brand names on recordOmeprazole
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.
Let's talk about taking olanzapine (a medicine for mood or thinking) together with omeprazole (a common heartburn and acid-reflux medicine, like Prilosec). Omeprazole may speed up how fast your body clears olanzapine. That means the olanzapine level in your blood could drop, and it might not work as well as it should.
Please don't change anything on your own. This is something your care team can handle easily, often by adjusting your olanzapine dose or by keeping a closer eye on how you're doing. If you notice your usual symptoms creeping back, let your pharmacist or doctor know so they can help.
Effect: Reduced olanzapine exposure and potential loss of efficacy.
Mechanism: Omeprazole is a CYP1A2 inducer; olanzapine is partly metabolized by CYP1A2, so induction increases olanzapine clearance and lowers serum concentrations. Neither drug's active moiety depends on this pathway (no prodrug flip).
- Direction: Decreased olanzapine levels/effect.
- Magnitude: Not directly quantified; by analogy, discontinuing the inducer carbamazepine raised olanzapine levels ~114%.
- Evidence: Theoretical.
- Onset: Unspecified.
- Management: Monitor clinical response; olanzapine dose may need individualized upward adjustment while on omeprazole and re-evaluation if omeprazole is stopped.
What happens
Reduced OLANZapine exposure and reduced efficacy of OLANZapine
Interaction Deep Dive
Taking OLANZapine together with omeprazole can induce CYP1A2 and thereby raise OLANZapine clearance. In patients treated concurrently with omeprazole, an increase in the OLANZapine dose should be considered 12. A case report noted that following discontinuation of carBAMazepine (a CYP1A2 inducer), OLANZapine serum concentrations rose by 114% 3.
Why it happens (mechanism)
Induction of CYP1A2-mediated metabolism of OLANZapine
How to manage this interaction
Good news: this is manageable, and you should keep taking both medicines as prescribed unless your care team tells you otherwise.
- Your prescriber may adjust and individualize your olanzapine dose while you are also taking omeprazole, since omeprazole can lower olanzapine levels.
- Your team may monitor you more closely for whether your olanzapine is still working well.
- Tell your pharmacist or doctor if your original symptoms return or seem harder to control.
- Also mention if you ever stop omeprazole, since that could raise your olanzapine level again and may prompt a re-check.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Giving OLANZapine, which is a CYP1A2 substrate, together with carBAMazepine 200 mg twice daily (a CYP1A2 inducer) produced roughly a 50% rise in the clearance of OLANZapine 2.
b) A 23-year-old woman with paranoid schizophrenia received carBAMazepine 600 mg daily for aggressive outbursts along with perphenazine, which was her only medication at the time of admission. OLANZapine 15 mg daily was initiated, and her psychiatric symptoms got better over the following 3 weeks. Since her aggressive outbursts persisted, carBAMazepine was stopped because it was not effective. On the day before carBAMazepine was discontinued, the OLANZapine serum concentration measured 21 ng/mL. During the subsequent weeks after carBAMazepine was stopped, the OLANZapine concentration rose by 114% to 45 ng/mL. The OLANZapine dose was lowered to 10 mg daily, and a matching decrease in the OLANZapine level followed 3.
Common questions
Can I take Omeprazole and Olanzapine together?
Omeprazole may lower olanzapine levels and make it less effective, so your care team may adjust your olanzapine dose or monitor you more closely. Keep taking both as prescribed and report any return of symptoms. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Olanzapine 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 Olanzapine interaction managed?
Good news: this is manageable, and you should keep taking both medicines as prescribed unless your care team tells you otherwise. Your prescriber may adjust and individualize your olanzapine dose while you are also taking omeprazole, since omeprazole can lower olanzapine levels. Your team may monitor you more closely for whether your olanzapine is still working well. Tell your pharmacist or doctor… 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:
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- Concerns Taking Itraconazole And Olanzapine Together
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- Is Sea Moss Safe To Take With Omeprazole?
- Interaction Question: Omeprazole, Spironolactone And Phentermine
- How To Dose Omeprazole And Sucralfate Together
Questions for your pharmacist
- Does my dose of Omeprazole or Olanzapine 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: SYMBYAX(R) oral capsules, olanzapine fluoxetine oral capsules. Lilly USA LLC (per FDA), Indianapolis, IN, 2023.
- Product Information: LYBALVI(R) oral tablets, olanzapine samidorphan oral tablets. Alkermes Inc (per FDA), Waltham, MA, 2024. DailyMed
- Licht RW, Olesen OV, Friis P, et al: Olanzapine serum concentrations lowered by concomitant treatment with carbamazepine (letter). J Clin Psychopharmacol 2000; 20:110-112. PubMed
Keep reading about Olanzapine
Keep reading about Omeprazole
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