SSRI-Induced Hyponatremia

Incidence and Prevalence

The incidence of SSRI-induced hyponatremia varies widely across studies, from 0.5% to 32%, with most clinically significant cases occurring in older adults, and the American Family Physician reports an odds ratio of 3.3 (95% CI, 1.3 to 8.6) for SSRIs compared with other antidepressant drug classes in geriatric populations 1
In geriatric populations specifically, hyponatremia rates of 0.5% to 12% have been documented, according to the American Family Physician 1
The 2019 American Geriatrics Society Beers Criteria explicitly identifies SSRIs as medications associated with hyponatremia or syndrome of inappropriate antidiuretic hormone secretion (SIADH) in older adults, as stated by the American Geriatrics Society 2

Age ≥65 years is the single strongest predictor of SSRI-induced hyponatremia, and concomitant diuretic use, especially thiazides, dramatically amplifies risk, according to the American Family Physician and the American Geriatrics Society 1, 2
The American Geriatrics Society recommends avoiding combining SSRIs with thiazide diuretics in elderly patients when possible, as this combination substantially increases hyponatremia risk 2, 1

For prevention and early detection, the American Family Physician recommends checking baseline serum sodium before initiating SSRI therapy in patients ≥65 years, those on diuretics, or with other risk factors 1
The American Geriatrics Society suggests avoiding combining SSRIs with thiazide diuretics in elderly patients when possible, and the combination of trimethoprim-sulfamethoxazole with ACE inhibitors or ARBs also increases electrolyte disturbance risk and should be used cautiously in elderly patients on SSRIs 2, 1