We report PPI-induced hyponatremia occurring with two different agents. Hyponatremia is highly prevalent in both ambulatory and hospitalized patients [
1,
5]. A prospective observational study found that hyponatremia in older patients with fragility fractures is mostly multifactorial, whereby dehydration and PPI use were the most associated factors [
9]. The authors acknowledged that PPI-induced hyponatremia is infrequently reported and that their results possibly reflect the high prevalence of PPI prescribing in older hospitalized patients [
9]. In other studies, PPI-induced hyponatremia has been reported as a rare cause of drug-induced hyponatremia [
6,
10]. Unfortunately, we cannot exclude pseudohyponatremia in this case completely. Although highly unlikely, glucose, triglycerides, and lipids were not measured because our patient’s medical history did not reveal diabetes or hypercholesterolemia and his general practitioner had measured a normal glucose prior to the referral. PPIs are worldwide prescribed drugs and on short-term use PPIs are regarded as effective and safe. However, with long-term use several adverse effects are reported, such as a changed gut microbiome, fundic mucosal hypertrophy,
Clostridium difficile infection, vitamin B12 deficiency, hypomagnesemia, and acute interstitial nephritis [
11]. There are only a few reports on PPI-induced hyponatremia with either omeprazole or pantoprazole [
12‐
15]. Durst
et al. reported the re-occurrence of hyponatremia after reintroducing omeprazole [
12]. To the best of our knowledge, this is the first report of hyponatremia occurring after the use of a second PPI. This is of clinical relevance because not only are PPIs one of the most prescribed drugs, but also, when PPI-induced hyponatremia is diagnosed, the clinician should be aware that switching to another PPI potentially does not solve the problem.