Are Antidepressants Associated with Severe Hyponatremia?

Selective serotonin reuptake inhibitors (SSRIs) and certain other antidepressants have long been connected with hyponatremia, but we have had only small observational studies to support this association. In this Swedish study, researchers analyzed data from 234,000 first-time users of SSRIs or venlafaxine. Each patient served as his or her own temporal control in a comparison of hyponatremia incidence before and after drug initiation.

Profound hyponatremia, defined as serum sodium level <125 mEq/L, was most likely to occur in the first 3 months after drug initiation (adjusted odds ratio, 4.3, compared with 1 year prior). Risk subsequently diminished; no significant difference was noted in incidence at 1 year after drug initiation in those wh…