Serotonin Syndrome Differential Diagnosis

Table 2.8.3 Differential diagnosis of serotonin syndrome

Condition	Drug History	Cadence	Vital signs	Pupils	Skin	Bowel sounds	Neuromuscular tone	Reflexes	Mental Status
Serotonin syndrome	5HT_2Aor 5HT_1Aagonist	< 12 hours	↑HR, BP, RR and Temp	Mydriasis	Sweaty	Hyperactive	Increased, especially lower limbs	Hyperreflexia and clonus	Agitation progressing to coma
Neuroleptic Malignant syndrome	Dopamine antagonist	Days	↑HR, BP, RR and Temp	Mydriasis or normal	Sweaty but pale	Normal	Lead-pipe rigidity	Bradyreflexia	Mutism, staring, bradykinesia, coma
Anticholinergic syndrome	Anticholinergic agent	< 12 hours	↑HR, BP, RR and Temp	Mydriasis	Hot, red and dry	Decreased or absent	Normal	Normal	Agitated delirium
Malignant Hyperthermia	Inhalational anaesthetic	Minutes-24 hours	↑HR, BP, RR and Temp	Normal	Sweaty and mottled	Decreased	Generalised rigidity	Hyporeflexia	Agitation

Adapted from: Boyer EW and Shannon M. The serotonin syndrome. New England Journal of Medicine 2005; 352(11):1112-1120.