What are the key clinical features to recognize Neuroleptic Malignant Syndrome (NMS) in a patient on antipsychotic medication?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 22 August 2025Updated: 22 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Key clinical features to recognize Neuroleptic Malignant Syndrome (NMS) in a patient receiving antipsychotic medication include:

  • Hyperthermia: A high fever is a hallmark feature, often exceeding 38°C, reflecting the systemic inflammatory response .
  • Muscle rigidity: Severe, generalized 'lead-pipe' rigidity is characteristic and differentiates NMS from other conditions .
  • Autonomic dysfunction: Manifested by labile or elevated blood pressure, tachycardia, diaphoresis, and tachypnoea .
  • Altered mental status: Ranging from agitation and confusion to stupor and coma, indicating central nervous system involvement .
  • Elevated creatine kinase (CK): Marked elevation due to muscle breakdown supports the diagnosis, although this is a laboratory rather than clinical feature .
  • Other features: May include leukocytosis and metabolic acidosis .

Recognition requires a high index of suspicion in any patient on antipsychotics presenting with this constellation of symptoms, as early diagnosis and management are critical . While atypical antipsychotics may present with a somewhat atypical or less severe syndrome, the core features remain consistent .

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