Can Long-Term Proton Pump Inhibitor Use Cause Fatigue?

Written by the Nuvirox Research Team

Short answer: possibly, for some people, primarily through B12 deficiency — and it's worth testing for rather than assuming. Proton pump inhibitors (omeprazole, esomeprazole, pantoprazole, and similar drugs) work by reducing stomach acid, and that acid plays a role most people don't think about: helping release vitamin B12 from food so it can be absorbed. Long-term PPI use has been studied for its association with lower B12 status, and B12 deficiency is a well-established, correctable cause of fatigue — but the population-level evidence on how strong this link actually is has been genuinely mixed.

How would a stomach acid medication affect your energy?

Vitamin B12 in food is bound to protein, and stomach acid is required to cleave it free before it can bind to intrinsic factor and be absorbed in the small intestine. PPIs suppress that acid production by design (that's how they treat reflux and ulcers), and the concern is that over years of use, this can gradually reduce B12 absorption enough to cause a measurable deficiency in some people [1].

What does the actual research show?

A 2025 systematic review and meta-analysis pooling six studies (1,587 chronic PPI users and 2,272 controls) found an association between long-term PPI use (defined as more than 6 months) and reduced serum vitamin B12 alongside elevated homocysteine, a biomarker of B12 status [1]. The review also cites an earlier meta-analysis finding a hazard ratio of 1.83 for B12 deficiency with long-term acid-suppressing drug use, indicating a meaningfully higher risk, though not a certainty, for chronic users [1].

Is the evidence actually settled?

No, and that's an important honest note. A dedicated study of 125 long-term (over 3 years) PPI users compared against 125 non-user partners found the results on this specific question have been inconsistent across the literature, with earlier research using varying methods and deficiency definitions [2]. Some cross-sectional and cohort studies find a clear association; others don't reach the same conclusion, likely reflecting differences in dose, duration, baseline diet, and how "deficiency" is defined.

What the evidence actually shows, study by study

The 2025 meta-analysis of six pooled studies found a measurable association between chronic PPI use and both lower serum B12 and elevated homocysteine, two independent markers pointing the same direction [1].

An earlier meta-analysis cited within that review reported a hazard ratio of 1.83 for B12 deficiency among long-term users of acid-suppressing medication, translating to meaningfully elevated but not universal risk [1].

Honest counterweight: the 125-patient elderly cohort study explicitly notes that findings across the PPI-B12 literature have been inconsistent, with some studies using small samples, poor controls, or inconsistent deficiency thresholds [2]. This isn't a settled, universal effect — it's a real but variable risk that depends on individual factors like diet, duration of use, and dose.

What this doesn't mean you should do

This is not a reason to stop a PPI you've been prescribed without talking to your doctor first — untreated reflux, ulcers, or other conditions PPIs are prescribed for carry their own real risks. It also doesn't mean every long-term PPI user is B12 deficient; many aren't. The right move if you're on a long-term PPI and experiencing unexplained fatigue is a simple blood test for B12 (and possibly homocysteine or methylmalonic acid, more sensitive markers), not assuming or self-treating.

What actually helps

If a blood test confirms B12 deficiency, your doctor can recommend an appropriate correction — oral, sublingual, or injectable B12 depending on severity and absorption concerns. Some clinicians periodically monitor B12 in patients on long-term PPI therapy as routine practice; it's reasonable to ask whether that's being done for you if you've been on a PPI for several years.

What other factors can confound this picture?

Several things make the PPI-B12-fatigue relationship harder to pin down cleanly at an individual level. Age is one: older adults are both more likely to be on long-term PPIs and more likely to have age-related declines in B12 absorption independent of any medication, since stomach acid production naturally decreases somewhat with age. Diet is another: vegetarians and vegans have lower dietary B12 intake to begin with, so a PPI's effect on absorption may matter more for someone already running closer to the margin. Duration and dose also matter more than most people assume — someone on a low-dose PPI for eight weeks after an ulcer is in a very different risk category than someone who has been on a high-dose PPI continuously for fifteen years for severe reflux disease.

There's also a practical diagnostic wrinkle: standard serum B12 tests can appear normal even when a functional deficiency is developing, since methylmalonic acid and homocysteine (more sensitive markers of B12 status at the cellular level) can be abnormal before serum B12 itself drops out of range. If your fatigue is genuinely unexplained and you've been on a PPI for years, asking your doctor specifically about these more sensitive markers, not just a standard B12 level, can be a more thorough way to rule this out.

Frequently asked questions

How long do you have to be on a PPI before B12 deficiency becomes a concern?
Most of the research on this topic focuses on use beyond 6 months to several years; short courses of PPIs (weeks) are not typically linked to meaningful B12 depletion.

Should I get my B12 checked if I've been on omeprazole for years?
It's a reasonable, low-cost test to ask your doctor about, particularly if you're also experiencing unexplained fatigue, tingling, or memory changes.

Does switching PPI brands change the B12 risk?
The mechanism (reduced stomach acid) is shared across the PPI class, so switching brands within the same drug class is unlikely to meaningfully change the risk profile.

Can I just take a B12 supplement instead of getting tested?
Testing first is the better approach, since it confirms whether deficiency is actually present and lets your doctor guide the right form and dose if it is — guessing can mask other issues that share similar symptoms.

FROM NUVIROX

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The bottom line

The link between long-term PPI use and B12-related fatigue is real in the aggregate data but inconsistent at the individual level — which makes testing, not guessing, the right next step if you're on a PPI and feeling unusually tired. For general reading on evidence-based approaches to persistent tiredness, see our guide on chronic stress and fatigue or what to do when you’re tired but your labs look normal.

References

1. Association Between Long-Term Proton Pump Inhibitor Therapy and Vitamin B12 Status: A Systematic Review and Meta-Analysis (6 studies, 1587 cases/2272 controls). Cureus / PMC. PMC12351138.
2. Long-term use of proton pump inhibitors and vitamin B12 status in elderly individuals (n=125 long-term PPI users vs 125 non-user partners). PMID: 18194503.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice.