Thiazides and Risk of Hyponatremia by Age and Sex

Importance: Thiazide diuretics are a cornerstone for the treatment of hypertension, but their use is associated with development of hyponatremia. Women and older adults are particularly vulnerable, but population-based estimates of absolute risk are largely absent. Such data are a prerequisite for a robust risk-benefit assessment in the clinical setting. Objective: To compare new use of thiazide diuretics with calcium channel blockers (CCBs) and subsequent risk of hyponatremia among different age groups and between the sexes. Design, Setting, and Participants: This propensity score-matched cohort study included 159 080 individuals 18 years or older in the Stockholm Sodium Cohort, a research database established to investigate the association between thiazide and hyponatremia among individuals in Stockholm, Sweden, between July 1, 2006, and December 31, 2018. Statistical analysis was performed between January 2025 and January 2026. Exposure: Newly initiated treatment with thiazide diuretics and CCBs. Main Outcomes and Measures: The primary outcome was profound hyponatremia (ie, a sodium concentration