Neuroleptic malignant promethazine

Neuroleptic malignant syndrome (NMS) A potentially fatal symptom complex sometimes referred to as NMS has been reported in association with promethazine alone or in combination with antipsychotic drugs. Clinical manifestations of NMS are hyperpyrexia, muscle rigidity, altered mental status, and evidence of autonomic instability (eg, irregular pulse or blood pressure, tachycardia, diaphoresis, cardiac dysrhythmias). 

There have been reports of neuroleptic malignant syndrome precipitated by promethazine 100 mg/day to treat neuroleptic drug-induced extrapyramidal symptoms and lorazepam 6 mg/day to treat agitation (349), after the addition of intramuscular haloperidol 23 mg to atypical neuroleptic drugs (350), and in other instances in children and adolescents (351). 

Duggal HS, Nizamie SH. Neuroleptic malignant syndrome precipitated by promethazine and lorazepam. Aust NZ J Psychiatry 2001 35(2) 250-1. 

Chan-Tack KM. Neuroleptic malignant syndrome due to promethazine. South Med J 1999 92(10) 1017-18. 

Neuroleptic malignant syndrome has been associated with promethazine (1). 

---