See the DrugPatentWatch profile for omeprazole
Does omeprazole lower vitamin B12 levels?
Yes. Omeprazole can reduce vitamin B12 absorption over time. It does this by lowering stomach acid, which helps release vitamin B12 from food proteins. With less acid, less B12 is absorbed—especially during long-term use of proton pump inhibitors (PPIs) like omeprazole. [1]
What does the evidence say about long-term use?
The best-supported concern is for people who take PPIs for extended periods (often measured in years). In these cases, studies and clinical guidance have linked chronic acid suppression with lower vitamin B12 levels and, in some people, B12 deficiency. [1]
Who is most at risk for B12 deficiency from omeprazole?
Risk tends to be higher if you already have trouble absorbing B12 or are more likely to develop deficiency due to other factors, such as:
- Older age
- Low baseline B12 intake or borderline B12 levels
- Conditions that reduce stomach acid or intrinsic factor (for example, atrophic gastritis)
- Use of PPIs for long durations [1]
If I take omeprazole, should I take vitamin B12 or get tested?
Common practical approaches include:
- Checking vitamin B12 if you have symptoms that could fit deficiency (such as fatigue, numbness/tingling, balance problems, or anemia) or if you’re on long-term PPI therapy.
- Considering supplementation if labs show low B12 or if a clinician judges your risk to be higher. [1]
Whether you need testing or supplementation depends on your dose, how long you’ve been taking omeprazole, and your baseline risk.
How long would it take for B12 to become a problem?
The effect is usually not immediate. The main concern is sustained acid suppression over time. People on long-term PPI therapy are the group most often evaluated for B12 status, rather than those taking omeprazole for only short courses. [1]
Are there signs that I should contact a clinician?
Contact a clinician promptly if you have symptoms consistent with B12 deficiency (neurologic symptoms like numbness/tingling or walking trouble, or signs of anemia such as unusual fatigue or shortness of breath). These symptoms warrant evaluation regardless of the cause.
What should I do if I’m worried?
If you’ve been using omeprazole long-term and want to reduce risk, the usual next steps are to discuss:
- The lowest effective dose and whether ongoing PPI therapy is still necessary
- A vitamin B12 blood test if appropriate for your situation
- Supplementation if your levels are low [1]
Sources:
[1] National Institutes of Health (NIH), Office of Dietary Supplements. “Vitamin B12 Fact Sheet for Health Professionals.” https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/