Cyanocobalamin and Omeprazole: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Omeprazole
Cyanocobalamin
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 happens
Reduced cyanocobalamin absorption
Interaction Deep Dive
Daily treatment with any acid-suppressing medications over a long period of time (eg, longer than 3 years) may lead to malabsorption of cyanocobalamin (vitamin B12) caused by hypo-or achlorhydria. This diagnosis should be considered if clinical symptoms consistent with cyanocobalamin deficiency are observed in patients treated with omeprazole and sodium bicarbonate1.
Why it happens (mechanism)
Altered gastric pH
Literature reports
2 reports — tap to read
a) A prospective study involving 10 healthy volunteers demonstrated that omeprazole therapy for 2 weeks duration resulted in a decrease of 90% (p=0.031) in protein-bound cyanocobalamin absorption 2.
b) Rare reports of cyanocobalamin deficiency occurring with acid-suppressing therapy have been reported in the literature 1.
Common questions
Can I take Cyanocobalamin and Omeprazole together?
Reduced cyanocobalamin absorption Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cyanocobalamin and Omeprazole 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 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 Cyanocobalamin or Omeprazole 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 (2)
- Product Information: KONVOMEP(TM) powder for oral suspension, omeprazole sodium bicarbonate powder for oral suspension. Azurity Pharmaceuticals Inc (per manufacturer), Woburn, MA, 2022. DailyMed
- Marcuard S, Albernaz L, & Khazanie PG: Omeprazole therapy causes malabsorption of cyanocobalamin (vitamin B12). Ann Intern Med 1994; 120:211-215.
Keep reading about Omeprazole
Keep reading about Cyanocobalamin
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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