Accidental hypothermia

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 24 Apr 2025

Last updated: 13 Feb 2025

Accidental hypothermia is defined by the unintentional lowering of core body temperature to <95°F (<35°C).

Classified as mild, moderate, or severe according to core temperature. Some experts have suggested a further (more severe) category of profound hypothermia, at a core temperature <75.2°F (<24°C) according to some and <68°F (<20°C) according to others.

Core temperature measured in the lower third of the esophagus correlates well with pulmonary artery temperature and is preferred in patients with a secure airway.

Initial management should focus on stopping further cooling, resuscitation, and supportive care. This includes removing the patient from the cold environment, careful removal of wet or cold clothing, insulation, warming the body, securing the airway, monitoring breathing and circulation, and maintaining circulation using warm intravenous fluids.

Choice of rewarming strategy (passive external, active external, active interna/corel) is based on the patient’s core temperature and clinical features; a combination of techniques may be used.

Patients who have sustained a hypothermic cardiac arrest should ideally be rewarmed in a specialist center using extracorporeal life support.

Definition

Accidental hypothermia is characterized by the unintentional lowering of core body temperature to <95°F (<35°C).[1]

A threshold of 96.8°F (36°C) has been adopted in patients with trauma given that hypothermia is associated with higher mortality in this patient group.[2][3]

This topic covers accidental hypothermia in adults.

History and exam

Key diagnostic factors

cold exposure and body temperature <95°F (<35°C)
impaired mental status
shivering
frostbite

Full details

Other diagnostic factors

tachypnea, tachycardia, hypertension
respiratory depression, bradycardia, hypotension
coma and apnea
cold-induced diuresis

Full details

Risk factors

trauma
drowning
general anesthetic use
substance misuse
impaired cognition
hypothyroidism
stroke
Parkinson disease
homelessness
extremes of age
gram-negative septicemia
immobility
use of certain drugs

Full details

Diagnostic tests

1st tests to order

core temperature measurement
12-lead ECG
CBC
serum electrolytes
blood glucose
ABG
clotting screen
chest x-ray

Full details

Tests to consider

serum creatinine kinase
myoglobin levels
end-tidal CO₂
ultrasound

Full details

Treatment algorithm

ACUTE

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

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

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

Contributors

Authors

Emmanuel Atta Agaba, MD, FRCSEd, FACS

Attending Surgeon

Assistant Professor of Surgery

Montefiore Medical Center at Albert Einstein College of Medicine

Bronx

Disclosures

EAA declares that he has no competing interests.

Acknowledgements

Dr Emmanuel Agaba would like to gratefully acknowledge Dr Rafael Barrera and Dr Juan Jose Gilbert, previous contributors to this topic.

Disclosures

RB and JJG declare that they have no competing interests.

Peer reviewers

Wail Malaty, MD

Clinical Professor

Department of Family Medicine

University of North Carolina

Chapel Hill

Assistant Program Director

MAHEC Rural Family Medicine Residency

Hendersonville

Disclosures

WM declares that he has no competing interests.

James S. Milledge, MBBS

Honorary Professor

Department of Physiology

University College London

London

Disclosures

JSM declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Paal P, Pasquier M, Darocha T, et al. Accidental hypothermia: 2021 update. Int J Environ Res Public Health. 2022;19(1):501.Full text Abstract

Lott C, Truhlář A, Alfonzo A, et al. European Resuscitation Council guidelines 2021: cardiac arrest in special circumstances. Resuscitation. 2021 Apr;161:152-219.Full text Abstract

Panchal AR, Bartos JA, Cabañas JG, et al. Part 3: adult basic and advanced life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020 Oct 20;142(16 Suppl 2):S366-468.Full text Abstract

Dow J, Giesbrecht GG, Danzl DF, et al. Wilderness Medical Society clinical practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia: 2019 update. Wilderness Environ Med. 2019 Dec;30(4 Suppl):S47-69.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Sepsis
- Hypothyroidism
- Hypoglycemia
More Differentials
Guidelines
- Clinical staging of accidental hypothermia: the revised Swiss system recommendation of the International Commission for Mountain Emergency Medicine (ICAR MedCom)
- European Resuscitation Council guidelines 2021: cardiac arrest in special circumstances
More Guidelines
Calculators
Hypothermia outcome prediction after ECLS (HOPE) score
More Calculators
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Accidental hypothermia

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Treatment algorithm

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

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

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

Contributors

Authors

Emmanuel Atta Agaba, MD, FRCSEd, FACS

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Wail Malaty, MD

Disclosures

James S. Milledge, MBBS

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Calculators

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice