Falhammar H, et al. - This register-based case-control study was based on the general Swedish population which intended to evaluate the relationship between proton pump inhibitors (PPIs) and hospitalization due to hyponatremia. Using multivariable logistic regression adjusting for concomitant drugs, medical conditions, previous hospitalizations and socioeconomic factors, the connection between newly initiated (≤90 days) and ongoing PPI use was investigated. An association was found between any newly initiated PPI-treatment and hospitalization due to hyponatremia. Lansoprazole was an exception with no association found. Findings suggested no association of severe hyponatremia with ongoing PPI treatment.