We report the development of hyponatremia following initiation of escitalopram therapy in a 73-year-old woman. The patient, with a history of dementia with Lewy bodies, had presented with multiple neuropsychiatric symptoms. Within 2 months of escitalopram, she became delirious with a serum sodium level of 122 mmol/L. After discontinuation of escitalopram, her consciousness improved with resolving hyponatremia. Delirium and hyponatremia (122 mmol/L), however, recurred after escitalopram was rechallenged. Apart from eight other cases to date, this is the only one with recurrent hyponatremia. Rechallenge of the same antidepressant is discouraged especially in patients at risk of developing hyponatremia.