Omeprazole and Citalopram: 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
Citalopram
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. Your body uses a liver enzyme called CYP2C19 to break down citalopram (Celexa). Omeprazole (Prilosec) slows that enzyme down, so citalopram can build up a bit higher in your body than usual.
Why does that matter? Citalopram can affect your heart's rhythm at higher doses (something called QT prolongation). More citalopram in your system means a slightly higher chance of that. The good news is this is very manageable. Your care team can keep your citalopram dose in a safe range and check your heart rhythm if needed. Please don't stop either medicine on your own, just bring it up with your pharmacist or doctor.
Mechanism: Omeprazole inhibits CYP2C19, the primary enzyme clearing citalopram, increasing citalopram exposure (AUC/Cmax). Citalopram is an active drug (not a prodrug), so higher exposure means enhanced pharmacodynamic effect.
Clinical concern: Citalopram causes dose-dependent QT prolongation; increased exposure raises torsadogenic risk.
- Evidence: theoretical; onset: unspecified; severity: major.
- Management: Limit citalopram to a maximum of 20 mg/day with concomitant omeprazole.
- Consider baseline/follow-up ECG; discontinue citalopram if persistent QTc greater than 500 ms.
- Assess other QT-prolonging agents and electrolytes (K+, Mg2+).
What happens
Increased citalopram exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Citalopram has been linked to lengthening of the QT interval in a manner that depends on the dose. When taken together, citalopram exposure may rise, raising the likelihood of QT prolongation. Should citalopram need to be given alongside omeprazole, citalopram doses should be kept at or below 20 mg/day21, and citalopram should be stopped in any patient whose QTc readings remain above 500 milliseconds2.
Why it happens (mechanism)
Inhibition of CYP2C19-mediated metabolism of citalopram by omeprazole
How to manage this interaction
The takeaway: this is manageable with the right dose and some monitoring.
- Keep taking both medicines exactly as prescribed unless your care team tells you otherwise.
- When these two are used together, citalopram is usually capped at 20 mg per day. Your prescriber may set your dose with this in mind.
- Your team may check your heart rhythm with an ECG and would act if your QTc stays too high.
- Tell your pharmacist or doctor about any other medicines that affect heart rhythm.
- Call your doctor if you feel fainting, dizziness, or a fluttering or pounding heartbeat.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a pharmacokinetic study involving patients who took citalopram 40 mg/day for 21 days, adding cimetidine (a potent CYP2C19 inhibitor) 400 mg/day for 8 days led to increases in citalopram AUC and Cmax of 43% and 39%, respectively. However, the interaction between citalopram (a CYP2C19 substrate) and omeprazole (another CYP2C19 inhibitor) has not been specifically studied 23.
Common questions
Can I take Omeprazole and Citalopram together?
Omeprazole can raise citalopram levels and increase the risk of a heart-rhythm change (QT prolongation), so citalopram is generally kept at or below 20 mg/day when used together, with heart monitoring if needed. Keep taking both as prescribed and review the dose with your pharmacist or doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Citalopram 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 Citalopram interaction managed?
The takeaway: this is manageable with the right dose and some monitoring. Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. When these two are used together, citalopram is usually capped at 20 mg per day. Your prescriber may set your dose with this in mind. Your team may check your heart rhythm with an ECG and would act if your QTc stays too high. Tell you… 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
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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 Citalopram 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: CELEXA(R) oral tablets, citalopram oral tablets. Allergan USA Inc (per FDA), Madison, NJ, 2023. DailyMed
- Product Information: PRILOSEC(R) delayed-release oral capsules, omeprazole delayed-release oral capsules. AstraZeneca LP, Wilmington, DE, 2011. DailyMed
Keep reading about Citalopram
Keep reading about Omeprazole
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