Accidental hypothermia

Last reviewed: 26 Feb 2023
Last updated: 23 Dec 2021



History and exam

Key diagnostic factors

  • presence of risk factors
  • cold exposure and body temperature <35°C (<95°F)
  • cognitive impairment
  • shivering
  • frostbite
Full details

Other diagnostic factors

  • tachypnoea, tachycardia, hypertension
  • respiratory depression, bradycardia, hypotension
  • coma and apnoea
  • cold-induced diuresis
Full details

Risk factors

  • general anaesthetic use
  • older age
  • very young age
  • immobility
  • substance misuse
  • impaired cognition
  • hypothyroidism
  • stroke
  • Parkinson's disease
  • homelessness
  • gram-negative septicaemia
  • neuroleptic medication
  • beta-blocker medication
  • sedative hypnotic medication
Full details

Diagnostic investigations

1st investigations to order

  • core temperature measurement
  • 12-lead ECG
  • blood glucose
  • blood gas
  • serum urea, electrolytes, and creatinine
  • FBC
  • clotting screen
  • chest x-ray
Full details

Investigations to consider

  • serum creatine kinase
  • myoglobin levels
  • end-tidal CO₂
  • ultrasound
Full details

Treatment algorithm


moderate or severe hypothermia in cardiac arrest: ≤32°C (≤90°F)

moderate or severe hypothermia not in cardiac arrest: ≤32°C (≤90°F)

mild hypothermia: >32°C to 35°C (>90°F to 95°F)


Expert advisers

Alexander Alexiou, MBBS, BSc, DCH, FRCEM, Dip IMC RCSEd

Emergency Medicine Consultant

Barts Health NHS Trust

Physician Response Unit Consultant

London’s Air Ambulance

Royal London Hospital




AA declares that he has no competing interests.

Melvyn Jenkins-Welch, MBBS, BSc, MSc, FRCA, FFICM

Consultant Critical Care Medicine

Cardiff and Vale ULHB




MJW declares that he has no competing interests.


BMJ Best Practice would like to gratefully acknowledge the previous expert contributors, whose work has been retained in parts of the content:

Emmanuel Atta Agaba, MD, FRCSEd, FACS

Attending Surgeon

Assistant Professor of Surgery

Montefiore Medical Center at Albert Einstein College of Medicine



Rafael Barrera, MD, FACP


Surgical Intensive Care Unit

Long Island Jewish Medical Center

New Hyde Park


Peer reviewers

Patrick Morgan, MBChB, FRCA, FFICM, Dip IMC RCSEd, DiMM

Consultant in Anaesthesia

North Bristol NHS Trust


Pre-hospital and Retrieval Doctor

Emergency Medical Retrieval and Transfer Service (EMRTS) Cymru



PM is Medical Director, HM coastguard (UK). PM has been a medical expert witness in hypothermia, cold water-immersion and drowning. PM is a Research Associate/student at the Extreme Environments Laboratory, University of Portsmouth.


Annabel Sidwell

Section Editor, BMJ Best Practice


AS declares that she has no competing interests.

Tannaz Aliabadi-Oglesby

Lead Section Editor, BMJ Best Practice


TAO declares that she has no competing interests.

Adam Mitchell

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

Julie Costello

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

  • Differentials

    • Sepsis
    • Hypothyroidism
    More Differentials
  • Guidelines

    • European Resuscitation Council guidelines for resuscitation 2021
    • Clinical practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia
    More Guidelines
  • Calculators

    Glasgow Coma Scale

    More Calculators
  • padlock-lockedLog in or subscribe to access all of BMJ Best Practice

Use of this content is subject to our disclaimer