MB and serotonin syndrome: While initial clinical evaluation and investigations ruled out probable infective and metabolic causes, the rapid onset and progression of the disease and the absence of concurrent antipsychotic drug usage in this case, and a negative urinary myoglobin level clearly ruled out the possibility of neuroleptic malignant syndrome, malignant hyperthermia, lethal catatonia, and central anticholinergic syndrome.[9] Finally, the quick response to a serotonin receptor antagonist like cyproheptadine substantiates the diagnosis of serotonin syndrome.