Diaphoresis and dehydration during neuroleptic malignant syndrome: preliminary findings.

Serum osmolality and its relationship to diaphoresis and polydipsic behavior were examined in a series of 38 episodes of neuroleptic malignant syndrome (NMS) in 29 patients. Clinical variables were associated with significantly higher serum osmolality, and diaphoresis tended to emerge earlier than polydipsia in the course of NMS. The findings of this study are consistent with the hypothesis that, at least in some NMS patients, diaphoresis leads to dehydration followed by physiologically appropriate thirst and increased oral water intake. It appears that intravenous hydration is often necessary to correct the significant free water deficit that can occur during the course of NMS.