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Drug interactions between omeprazole and Vitamin B12

Results for the following 2 drugs:
Vitamin B12 (cyanocobalamin)

Interactions between your drugs


omeprazole ↔ cyanocobalamin

Applies to:omeprazole and Vitamin B12 (cyanocobalamin)

By reducing or suppressing gastric acid secretion, H2-receptor antagonists and proton pump inhibitors may interfere with the gastrointestinal absorption of vitamin B12, a process that is dependent on the presence of gastric acid and pepsin. Clinical studies have shown that dietary (i.e., protein-bound) vitamin B12 malabsorption can occur during treatment with these agents, particularly proton pump inhibitors, although the likelihood of developing clinically significant deficiency over time is unknown. There has been one reported case of vitamin B12 deficiency with megaloblastic anemia in a patient who received omeprazole at a minimum of 40 mg/day for 4 years. Also uncertain is whether acid reduction or suppression can affect the absorption of vitamin B12 ingested in the form of oral supplements such as cyanocobalamin. Non-oral routes of administration (e.g., parenteral, intranasal, sublingual) are generally preferred in the treatment of B12 deficiency-related anemia.


  1. Dutta SK "Vitamin b-12 malabsorption and omeprazole therapy." J Am Coll Nutr 13 (1994): 544-5
  2. Marcuard SP, Albernaz L, Khazanie PG "Omeprazole therapy causes malabsorption of cyanocobalamin (vitamin-b12)." Ann Intern Med 120 (1994): 211-5
  3. Bradford GS, Taylor CT "Omeprazole and vitamin B-12 deficiency." Ann Pharmacother 33 (1999): 641-3
  4. Lavy NW "Omeprazole and vitamin B12." Ann Intern Med 121 (1994): 74
  5. Salom IL, Silvis SE, Doscherholmen A "Effect of cimetidine on the absorption of vitamin B12." Scand J Gastroenterol 17 (1982): 129-31
View all 5 references

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Drug and food interactions

No results found in our database - however, this does not necessarily mean no interactions exist. Always consult with your doctor or pharmacist.

Therapeutic duplication warnings

No therapeutic duplications were found for your selected drugs.

Drug Interaction Classification

The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No information available.

Do not stop taking any medications without consulting your healthcare provider.

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