Last reviewed: March 2020
Last updated: July  2018



History and exam

Key diagnostic factors

  • presence of risk factors
  • agitation, irrationality, restlessness, sometimes aggressive behaviour
  • hyperthermia >38°C (>100°F) but <39.5°C (<103°F)
  • hyperthermia >39.5°C (>103°F)
  • seizures
  • diaphoresis, flushed facial skin
  • tachycardia and palpitations
  • traumatic injury
  • headache
  • serotonin drug interaction
  • hypertension
  • hyperreflexia and clonus
  • chest pain
  • cardiac arrhythmia

Other diagnostic factors

  • hx of hepatitis B or C, HIV
  • tremor, repetitive movements
  • disorientation, confusion, delirium
  • malnutrition
  • superficial venous abnormalities
  • rapid speech, pacing, trismus
  • hallucinations or delusions
  • tremor, hypertonicity, or muscle rigidity
  • paranoia, hypervigilance, or psychosis
  • mydriasis
  • hx of heart disease
  • tachypnoea
  • dyspnoea
  • lack of thirst
  • abdominal pain
  • positive Babinski
  • focal neurological signs, papilloedema

Risk factors

  • high ambient temperature
  • volume depletion
  • exercise and sweating
  • excessive alcohol intake
  • polydrug usage
  • anxiety and depression
  • hx of behavioural disturbance
  • hx of delinquency or crime
  • ADHD
  • attendance at dance club or rave party
  • hx of drug misuse for more than 1 year
  • genetic predilection

Diagnostic investigations

1st investigations to order

  • serum glucose
  • serum electrolytes
  • serum creatinine, urea
  • ABG
  • serum AST, ALT, gamma-GT
  • serum PT, PTT, INR
  • urinalysis
  • urine toxicology screen
  • serum alcohol level
  • serum creatine kinase
  • serum troponin
  • ECG
  • CXR
More 1st investigations to order

Investigations to consider

  • serum D-dimer
  • abdominal x-ray
  • CT of the head
  • MRI of the head
  • cerebral angiography
More investigations to consider

Treatment algorithm



Department of Emergency Medicine

University of California, Davis Medical Center




JRR is an author of a number of references cited in this monograph.

Dr John R. Richards would like to gratefully acknowledge Dr Alison Jones, a previous contributor to this monograph. AJ is an author of a number of references cited in this monograph.

Peer reviewersVIEW ALL

Assistant Professor

Department of Emergency Medicine

Johns Hopkins University Hospital




AS declares that he has no competing interests.

Associate Clinical Professor of Medicine

University of California San Francisco School of Medicine

San Francisco



RJG declares that he has no competing interests.

Consultant Physician and Clinical Toxicologist

Guy's and St Thomas' Poisons Unit




DW is an author of a reference cited in this monograph.

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