Do Proton Pump Inhibitors Increase Your Risk of Iron Deficiency?
Yes. In this population-based case-control study of UK primary care records, people who took a proton pump inhibitor continuously for at least a year had 3.60 times the odds of a first iron deficiency diagnosis compared with people who had never been prescribed a PPI. Intermittent users had 1.51 times the odds. The proposed mechanism is the loss of stomach acid, which is needed to convert dietary iron into an absorbable form.
Dr. Kumar’s Take
The size of the effect in the continuous-use group is larger than I expected from a drug most patients think of as harmless. A 3.60-fold odds ratio in long-term users, with the risk climbing alongside both dose and duration, is a real signal, not statistical noise. Iron deficiency develops slowly and presents as fatigue, weakness, and poor exercise tolerance, symptoms that get blamed on almost anything else first. That combination, a common drug and a vague syndrome, is exactly how a side effect goes unrecognized for years. I read this as an argument for prescribing PPIs on a defined indication with a defined endpoint, and for checking iron status in the patients who stay on them.
What the Research Shows
The authors set out to settle a long-running debate about whether PPI therapy causes iron deficiency. Hypochlorhydria, a state of low stomach acid, is an established cause of iron deficiency, and PPIs suppress acid by design, so the biological argument was already there. The question was whether it showed up in a large real-world population.
It did. Compared with never-users, the adjusted odds ratio for iron deficiency was 3.60 (95% CI 3.32 to 3.91) in full users and 1.51 (95% CI 1.44 to 1.58) in limited users. The authors also reported positive dose-response and time-response relationships, meaning higher doses and longer exposure tracked with higher risk. Their conclusion was direct: chronic PPI use increases the risk of iron deficiency, and physicians should weigh this when prescribing long term.
Study Snapshot
This was a case-control study drawn from the UK Clinical Practice Research Datalink, covering 2005 to 2016. Cases were 26,806 patients aged 19 or older with a first-time diagnosis of iron deficiency, and the date of that diagnosis set the index date. Each case was matched to one control by age, gender, and general practice.
Exposure was sorted into three groups. A PPI full user had received PPIs continuously for at least one year before the index date. A PPI limited user had received PPI therapy intermittently. A PPI non-user had received no PPI prescriptions before the index date. Odds ratios were estimated with conditional logistic regression.
Results in Real Numbers
- Cases: 26,806 adults with a first-time iron deficiency diagnosis, each matched to one control
- Exposure among cases: 2,960 full users, 6,607 limited users, 17,239 non-users
- Exposure among controls: 1,091 full users, 5,058 limited users, 20,657 non-users
- Continuous use of at least 1 year: adjusted OR 3.60 (95% CI 3.32 to 3.91) versus non-users
- Intermittent use: adjusted OR 1.51 (95% CI 1.44 to 1.58) versus non-users
- Dose and duration: positive dose-response and time-response relationships were observed
Safety, Limits, and Caveats
This is a case-control study, so it establishes association rather than proving causation. Confounding by indication is the obvious concern: the conditions that lead a physician to prescribe a PPI, including gastrointestinal bleeding, can themselves deplete iron. The authors matched on age, gender, and general practice and adjusted their estimates, but matched observational data cannot rule out every alternative explanation.
The dose-response and time-response gradients strengthen the case, since a purely spurious association would not usually scale with exposure. The analysis also rests on diagnoses recorded in a primary care database, which reflect what clinicians coded rather than a uniform screening protocol.
Practical Takeaways
- Treat long-term continuous PPI use as the higher-risk pattern; the odds ratio in that group was more than double the one in intermittent users
- Check iron status in patients who have been on a PPI continuously for a year or more
- Since risk rose with both dose and duration, use the lowest effective dose for the shortest period that controls symptoms
- Reassess whether the PPI is still indicated at each review, and attempt discontinuation when it is clinically reasonable
- Consider unexplained fatigue in a long-term PPI user a reason to look at iron rather than a reason to reassure
- Do not stop a PPI on your own if it was prescribed for a specific condition; raise the question with your prescriber
Related Studies and Research
- Vitamin B12 Intake From Animal Foods, Biomarkers, and Health Aspects
- Proton Pump Inhibitors and Risk of Fractures: Meta-Analysis of 11 International Studies
- Meta-Analysis: Proton Pump Inhibitors Moderately Increase Risk of Small Intestinal Bacterial Overgrowth
- Pharmacology of Proton Pump Inhibitors
- Episode 25: The Great GERD Mistake - How Medicine Made Heartburn Worse and How to Fix It
FAQs
How might PPIs cause iron deficiency?
The authors frame it through hypochlorhydria, a state of low stomach acid, which is an established cause of iron deficiency. PPIs suppress acid production, so the proposed pathway is reduced absorption of dietary iron.
Does the risk depend on how long I have been taking a PPI?
Yes. Patients on continuous therapy for at least a year had an adjusted odds ratio of 3.60, while intermittent users had 1.51. The study also found a positive time-response relationship, so longer exposure tracked with higher risk.
Does the dose matter?
The study reported a positive dose-response relationship, meaning higher exposure was associated with greater risk of iron deficiency.
Does this study prove PPIs cause iron deficiency?
It is a case-control study, so on its own it shows association. The authors concluded that chronic PPI use increases the risk, supported by the dose-response and time-response gradients and by the known link between low stomach acid and iron deficiency.
Should I have my iron levels checked if I am on a long-term PPI?
That is a reasonable conversation to have with your physician, particularly if you have been on continuous therapy for a year or more, since that was the group with the highest odds in this study.
Bottom Line
In 26,806 UK adults with a first diagnosis of iron deficiency and their matched controls, continuous PPI use for at least a year carried an adjusted odds ratio of 3.60, and intermittent use carried 1.51, with risk rising alongside dose and duration. The authors’ recommendation is the one I would give: weigh this against the benefit every time chronic PPI therapy is prescribed or renewed.
