Neuroleptic malignant syndrome and clozapine.

Clozapine is an atypical neuroleptic drug that was initially thought not to cause neuroleptic malignant syndrome (NMS). We report a case of NMS associated with clozapine as a single agent that developed in a patient with no prior history of NMS. In contrast to other reported cases of NMS with clozapine monotherapy in which rigidity was reported to be absent, our patient had classic NMS with lead-pipe rigidity. NMS should be included in the differential diagnosis of a febrile patient with a history of any neuroleptic treatment, including clozapine.