Risperidone-induced neuroleptic malignant syndrome.

Risperidone is an antipsychotic drug used for the treatment of schizophrenia. It was expected that this atypical neuroleptic agent would not cause dystonia or neuroleptic malignant syndrome (NMS) owing to its unique mechanism of action with attenuated anti-dopaminergic activity and more potent antiserotoninergic activity. We report the case of a geriatric patient in whom signs and symptoms consistent with NMS developed after 3 weeks of risperidone therapy. The patient presented with fever, mental status changes, tremor, and rigidity. His laboratory findings were significant for increased serum creatine phosphokinase, hypernatremia, and metabolic acidosis. There have been few reported cases of risperidone-induced NMS. Health care providers should be aware of the risk of risperidone-induced NMS.