Fever is a feature that occurs in which two conditions requiring urgent evaluation?

• A. Both neuroleptic malignant syndrome and serotonin syndrome
• B. Only NMS
• C. Only serotonin syndrome
• D. Neither

Answer: (A)

Fever signals a medical emergency when evaluating drug-related syndromes with neuromuscular and autonomic instability. In neuroleptic malignant syndrome, fever accompanies severe dopamine blockade from antipsychotics, along with marked rigidity, altered mental status, autonomic instability, and rising CK. The onset is typically days after a dose change, and without rapid treatment these patients can deteriorate quickly. In serotonin syndrome, fever arises from excessive serotonergic activity that drives rapid neuromuscular excitation (such as clonus and hyperreflexia), along with agitation and autonomic symptoms, usually within hours of starting or increasing a serotonergic agent. Both conditions can progress to life-threatening complications like rhabdomyolysis, renal failure, arrhythmias, and DIC, so they demand urgent evaluation and management: stop the offending drug, implement aggressive cooling and hydration, monitor vitals and labs, and provide syndrome-specific therapy (dantrolene or bromocriptine for NMS; cyproheptadine for serotonin syndrome). Therefore fever is a feature that occurs in both, making them the two conditions requiring urgent evaluation.