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- 1 Side effects of proton pump inhibitors
- 2 Side effects of reducing stomach acid
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Side effects of reducing stomach acid
The short version: less acid means less defense, and the risks are real enough in long-term use that acid suppression should be a temporary tool, not a permanent state.
Lower acid changes what survives the stomach. The best-supported harm is infection, especially C. difficile: observational meta-analyses found roughly double the risk in PPI users [3], and one analysis tracked risk still elevated a year after stopping [3]. Randomized trials tell a different story, finding no significant increase [9]. That gap is confounding, and it should make you treat the observational numbers as a signal, not a rate.
Acid is also needed for nutrient absorption. Long-term PPI users showed lower magnesium, about 19 in 100 versus 13 in 100 in non-users [7], with rare severe cases where magnesium and calcium crashed and seizures followed [5][6]. A small outpatient study found no such drop [4], so this is real but intermittent, likely dose and duration dependent. B12 absorption falls too, a 46% drop in median serum B12 on chronic therapy [8].
The hardest endpoint is death. A pooled analysis found PPIs slightly increased all-cause mortality versus H2 blockers, about 5 in 1,000 over the trial periods [1], and in veterans 45 excess deaths per 1,000 over 10 years [2].
| Harm | Comparison | Size |
|---|---|---|
| C. diff | PPI vs non-use (observational) | ~2x [3] |
| Low magnesium | Long-term vs non | 19.4% vs 13.5% [7] |
| Death | PPI vs H2 blocker (trials) | ~5 per 1,000 [1] |
My call: for a clear short-term indication, the trade is reasonable; for years of open-ended use, the accumulated signals justify the lowest dose and a real attempt at tapering. Confidence: moderate.
Sources used 9
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Proton Pump Inhibitors Versus Histamine-2 Receptor Antagonists Likely Increase Mortality in Critical Care: An Updated Meta-Analysis
An updated meta-analysis of ICU stress ulcer prophylaxis comparing proton pump inhibitors (PPIs) vs histamine-2 receptor antagonists (H2RAs) found a small but statistically significant increase in all-cause mortality with PPIs, based on 28,559 adults across multiple randomized t…
DOI: 10.1016/j.amjmed.2020.08.004 -
Estimates of all cause mortality and cause specific mortality associated with proton pump inhibitors among US veterans: cohort study
In US veterans, new PPI use was associated with 45.20 excess all-cause deaths per 1000 users over 10 years and excess mortality due to cardiovascular disease, chronic kidney disease, and upper gastrointestinal cancer, including among patients without documented indications.
DOI: 10.1136/bmj.l1580 -
Proton pump inhibitor (PPI) administration and Clostridioides difficile infection - is this a real clinical problem? A critical review of the literature
This critical review of six meta-analyses concludes that PPI use is associated with a statistically significant increase in Clostridioides difficile infection risk in adults and children, but the relationship remains controversial because of confounding and conflicting trial evi…
DOI: 10.12775/jehs.2023.48.01.001 -
Hypomagnesemia Among Outpatient Long-Term Proton Pump Inhibitor Users
Among low-risk outpatient gastroenterology patients, long-term PPI use was not associated with hypomagnesemia: serum magnesium levels were similar in users and nonusers, and no PPI user had a level below 1.7 mg/dL.
DOI: 10.1097/mjt.0000000000000154 -
A Rare Case of Seizures Secondary to Proton Pump Inhibitors-Induced Hypomagnesemia
A 78-year-old man with recurrent tonic-clonic seizures on long-term omeprazole had severe hypomagnesemia; after exclusion of other causes, omeprazole was discontinued and magnesium supplementation was given, followed by gradual normalization and recovery.
DOI: 10.33140/mcr.08.10.09 -
Severe acute neurological symptoms related to proton pump inhibitors induced hypomagnesemia responsible for profound hypoparathyroidism with hypocalcemia
This study presents two cases of severe neurological symptoms in patients induced by hypomagnesemia due to long-term use of proton pump inhibitors (PPIs), highlighting the need for awareness of this potential adverse effect.
DOI: 10.1016/j.clinre.2014.03.005 -
Hypomagnesemia as an Underrecognized Adverse Effect of Long-Term Proton Pump Inhibitor Therapy: Literature review
This narrative review consolidates evidence that long-term proton pump inhibitor therapy causes hypomagnesemia by raising intestinal luminal pH and impairing TRPM6/TRPM7-mediated magnesium absorption, and argues that routine magnesium monitoring in long-term PPI users is warrant…
DOI: 10.12775/jehs.2026.95.73646 -
Proton pump inhibitors
This opinion piece critically reviews potential adverse effects of proton pump inhibitors (PPIs), assesses the strength of the supporting evidence (noting a lack of Level 1 randomized trials), highlights Clostridium difficile infection and bone fractures as the best-supported ri…
DOI: 10.1097/MOG.0b013e328358d5b9 -
Proton pump inhibitors are not associated with an increased risk of Clostridioides difficile infection: a systematic review and meta-analysis of randomized controlled trials
This is a comprehensive PRISMA-guided meta-analysis of randomized controlled trials that finds proton pump inhibitors (PPIs) do not significantly increase the risk of Clostridioides difficile infection (CDI) compared with placebo or several acid-suppressive comparators in adults…
DOI: 10.1080/19490976.2025.2562341