Omeprazole and Carbamazepine: 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
Carbamazepine
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.
Let's talk about taking carbamazepine (Tegretol) and omeprazole (Prilosec) together. Omeprazole can slow down how your body breaks down carbamazepine, so the level of carbamazepine in your blood can climb. Since carbamazepine is a medicine where even small increases matter, that can mean more side effects like dizziness, drowsiness, blurred or double vision, unsteadiness, or nausea.
At the same time, carbamazepine can make your body clear omeprazole faster, so your heartburn or reflux medicine may not work as well. The good news is this is very manageable. Your care team can check your levels, watch for symptoms, and adjust your doses so both medicines stay safe and effective. Please don't stop either one on your own.
Effect: Bidirectional interaction. Omeprazole inhibits CYP3A4-mediated metabolism of carbamazepine, raising carbamazepine AUC and half-life and reducing clearance, increasing toxicity risk. Carbamazepine induces CYP3A4 and CYP2C19, lowering omeprazole exposure and efficacy.
- Direction: Increased carbamazepine exposure; reduced omeprazole exposure.
- Onset: Delayed. Evidence: Probable. Severity: Major.
- NTI concern: Carbamazepine has a narrow therapeutic index; small exposure changes are clinically meaningful.
Management: Monitor carbamazepine serum levels and for toxicity (ataxia, diplopia, sedation, hyponatremia). Assess omeprazole efficacy (persistent reflux symptoms). Carbamazepine dose may need reduction when omeprazole is added; individualize both doses.
What happens
Increased carBAMazepine exposure, an increased risk of carBAMazepine toxicity, reduced omeprazole exposure and reduced efficacy of omeprazole
Interaction Deep Dive
When carBAMazepine, which acts as a CYP3A4 substrate as well as a CYP3A4 inducer and CYP2C19 inducer, is given together with omeprazole, which functions as a CYP3A4 inhibitor, a CYP3A4 substrate, and a CYP2C19 substrate, the outcome can be higher carBAMazepine exposure alongside lower omeprazole exposure. Should the two be used concurrently, monitor carBAMazepine and omeprazole levels carefully and modify the dose of either carBAMazepine or omeprazole when necessary12. In a patient already titrated to a stable carBAMazepine dose who then begins omeprazole therapy, reducing the carBAMazepine dose may become necessary3. It has been documented that omeprazole prolongs the elimination half-life, raises the area under the concentration-time curve (AUC), and lowers the clearance of a single dose of carBAMazepine4.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of carBAMazepine; induction of CYP3A4-mediated metabolism of omeprazole; induction of CYP2C19-mediated metabolism of omeprazole
How to manage this interaction
Both medicines can usually be used together safely with the right oversight. Here is what typically happens:
- Your team may monitor your carbamazepine blood levels more closely and watch for signs of too much (drowsiness, dizziness, unsteadiness, double vision, nausea).
- Your carbamazepine dose may be adjusted and individualized, especially if omeprazole is started after you are already stable on carbamazepine.
- Your team may also check whether your omeprazole is still controlling your reflux or heartburn, since it may work less well.
What you should do: Keep taking both as prescribed, and let your pharmacist or prescriber know about new side effects or if reflux symptoms return.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Giving a single dose of carBAMazepine to nine patients who were on omeprazole therapy led to a lengthening of the carBAMazepine half-life (17.2 hours vs. 37.3 hours) and a rise in the AUC from 382 mcg/hr/mL to 668 mcg/hr/mL. CarBAMazepine clearance fell from 20.7 mL/hr/kg to 12.5 mL/hr/kg. These findings indicate that any adjuvant use of omeprazole has the capacity to affect carBAMazepine concentrations, and it should be given only with close monitoring of carBAMazepine serum levels 4.
b) An epileptic patient who was stabilized on carBAMazepine (900 mg daily) had a serum level of 7.5 mg/L. One day after clarithromycin (500 mg three times daily) and omeprazole (20 mg twice daily) were added, the carBAMazepine level had increased to 14 mg/L. Even with carBAMazepine dose reductions of 200 mg daily, the plasma level reached 20.8 mg/L. Clarithromycin was subsequently stopped, and metronidazole and bismuth subsalicylate were substituted. CarBAMazepine plasma levels returned to normal, despite the continuation of omeprazole therapy. Omeprazole induces hepatic microsomal cytochrome P450 2C enzymes, while carBAMazepine is metabolized by and induces CYP3A4. The differing metabolic pathways of omeprazole and carBAMazepine suggest that in this patient, clarithromycin alone accounted for the elevated carBAMazepine serum levels and that no drug interaction exists between omeprazole and carBAMazepine 5.
Common questions
Can I take Omeprazole and Carbamazepine together?
Omeprazole can raise carbamazepine levels (more toxicity risk), while carbamazepine can weaken omeprazole; your care team can manage this by monitoring and adjusting doses, so keep taking both as prescribed and report any new symptoms. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Carbamazepine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How is the Omeprazole and Carbamazepine interaction managed?
Both medicines can usually be used together safely with the right oversight. Here is what typically happens: Your team may monitor your carbamazepine blood levels more closely and watch for signs of too much (drowsiness, dizziness, unsteadiness, double vision, nausea). Your carbamazepine dose may be adjusted and individualized, especially if omeprazole is started after you are already stable on ca… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
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 Carbamazepine 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 (5)
- Product Information: Tegretol(R)-XR oral extended-release tablets, carbamazepine oral extended-release tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2023. DailyMed
- Product Information: Tegretol(R) oral chewable tablets, oral tablets, oral suspension, carbamazepine oral chewable tablets, oral tablets, oral suspension. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2023. DailyMed
- Product Information: CARBATROL(R) oral extended-release capsules, carbamazepine oral extended-release capsules. Takeda Pharmaceuticals America Inc (per FDA), Lexington, MA, 2023. DailyMed
- Dammann HG: Therapy with omeprazole and clarithromycin increases serum carbamazepine levels in patients with h. pylori gastritis (letter). Dig Dis Sci 1996; 41:519-521.
- Metz DC & Getz HD: Helicobacter pylori gastritis therapy with omeprazole and clarithromycin increases serum carbamazepine levels. Dig Dis Sci 1995; 40:912-915. PubMed
Keep reading about Carbamazepine
Keep reading about Omeprazole
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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