Heat stroke in adults

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Last reviewed: 5 May 2025
Last updated: 04 Sep 2024

Summary

Definition

History and exam

Key diagnostic factors

  • history of exposure to severe environmental heat or strenuous physical exercise
  • central nervous system dysfunction
  • hyperthermia (>40°C)
  • hot skin (dry or wet)
  • risk factors
Full details

Other diagnostic factors

  • intense thirst (heat stroke or heat exhaustion)
  • weakness (heat stroke or heat exhaustion)
  • anxiety (heat stroke or heat exhaustion)
  • dizziness (heat stroke or heat exhaustion)
  • syncope (heat stroke or heat exhaustion)
  • headache (heat stroke or heat exhaustion)
  • nausea/vomiting (heat stroke or heat exhaustion)
  • sinus tachycardia
  • tachypnoea
  • jaundice
  • muscle tenderness
  • hypotension
  • bruising and skin bleeding
Full details

Risk factors

  • older age
  • impaired cognition
  • patients unable to care for themselves
  • medicines
  • lack of acclimatisation to hot environments
  • pre-existing dehydration
  • obesity
  • poor physical condition
  • environmental factors
  • young, active people exercising intensely under hot, humid conditions
Full details

Diagnostic investigations

1st investigations to order

  • rectal temperature
  • FBC
  • liver function tests
  • renal function tests
  • glucose
  • electrolytes
  • arterial blood gases
  • creatine kinase
  • clotting profile
  • urinalysis
  • ECG
Full details

Treatment algorithm

ACUTE

heat stroke

heat exhaustion

Contributors

Expert advisers

Alexander Alexiou, MB, BS, BSc, DCH, FRCEM, Dip IMC RCSEd

Flight Doctor

Greater Sydney Area Helicopter Emergency Medical Service

Sydney

New South Wales

Australia

Disclosures

AA declares that he has no competing interests.

Acknowledgements

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

James L. Glazer, MD, FACSM, CAQSM

Assistant Professor

Tufts University School of Medicine

Boston

MA

Disclosures

JLG declares that he has no competing interests.

Peer reviewers

Helen Small, FRCEM, MSc Sports and Exercise Medicine

Consultant in Emergency Medicine

Barnet Hospital

Royal Free London

London

UK

Disclosures

HS declares that she 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

Lipman GS, Gaudio FG, Eifling KP, et al. Wilderness Medical Society clinical practice guidelines for the prevention and treatment of heat illness: 2019 update. Wilderness Environ Med. 2019 Dec;30(4s):S33-46.Full text  Abstract

Gauer R, Meyers BK. Heat-related illnesses. Am Fam Physician. 2019 Apr 15;99(8):482-9.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.
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  • Guidelines

    • Wilderness Medical Society clinical practice guidelines for the prevention and treatment of heat illness: 2019 update
    • Heat-related illnesses
    More Guidelines
  • Patient information

    Heat stroke

    More Patient information
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