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High altitude illness

Last reviewed: 3 Apr 2025
Last updated: 26 Oct 2023

Summary

Definition

History and exam

Key diagnostic factors

  • headache
  • ataxia
  • change in mental state: for example, tired, irritable, confused, forgetful, irrational
  • abnormal tone, power, and reflexes
Full details

Other diagnostic factors

  • nausea, vomiting, and loss of appetite
  • fatigue and weakness
  • dizziness or lightheadedness
  • difficulty sleeping
  • visual disturbance
  • shortness of breath
  • cough with or without sputum
  • rales
  • peripheral edema
  • accentuated pulmonary second sound
  • pyrexia
  • elevated respiratory rate
  • elevated heart rate
  • low arterial oxygen saturation
  • cyanosis
  • urinary incontinence or retention
  • retinal hemorrhages and papilledema on fundoscopy
  • chest pain
  • cranial nerve palsies (III, IV, and VI)
  • visual and auditory hallucinations, seizures, tinnitus, vertigo, tremors, speech disturbance, and deafness
Full details

Risk factors

  • high altitude
  • rapid ascent
  • low-altitude residence
  • history of previous altitude illness
  • younger age
  • exertion
  • poor awareness of high-altitude illness prior to travel
  • existing medical condition
Full details

Diagnostic tests

1st tests to order

  • clinical diagnosis
Full details

Tests to consider

  • arterial blood gases
  • chest radiography
  • ECG
  • chest ultrasound and echocardiography
  • WBC count
  • lumbar puncture
  • CT head
  • MRI head
Full details

Treatment algorithm

INITIAL

high-altitude ascent planned

ACUTE

AMS

HAPE only

HACE only

concurrent HAPE and HACE

Contributors

Authors

Jeremy S. Windsor, MBChB, DCH, FCARCSI

Specialist Registrar

Anaesthetics and Intensive Care Medicine

University College Hospital

London

UK

Disclosures

JSW is an author of a number of references cited in this topic.

Peer reviewers

James S. Milledge, MBBS

Honorary Professor

Department of Physiology

University College London

London

UK

Disclosures

JSM declares that he has no competing interests.

Mike Grocott, MD

Senior Lecturer

Intensive Care Medicine

University College Hospital

London

UK

Disclosures

MG declares that he has no competing interests.

Haibo Wang, MD, PhD

Assistant Professor

LSU Health Sciences Center

Shreveport

LA

Disclosures

HW 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

Centers for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 4: environmental hazards & risks - high elevation travel & altitude illness. May 2023 [internet publication].Full text

Roach RC, Hackett PH, Oelz O, et al. The 2018 lake louise acute mountain sickness score. High Alt Med Biol. 2018 Mar;19(1):4-6.Full text  Abstract

Luks AM, Auerbach PS, Freer L, et al. Wilderness medical society clinical practice guidelines for the prevention and treatment of acute altitude illness: 2019 update. Wilderness Environ Med. 2019 Dec;30(4s):S3-18.Full text  Abstract

Donegani E, Paal P, Küpper T, et al. Drug use and misuse in the mountains: a UIAA MedCom consensus guide for medical professionals. High Alt Med Biol. 2016 Sep;17(3):157-84. Abstract

Ritchie ND, Baggott AV, Andrew Todd WT. Acetazolamide for the prevention of acute mountain sickness - a systematic review and meta-analysis. J Travel Med. 2012 Sep-Oct;19(5):298-307.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.
  • High altitude illness images
  • Differentials

    • Asthma, acute exacerbation
    • Community-acquired pneumonia
    • Acute exacerbation of chronic heart failure (CHF)
    More Differentials
  • Guidelines

    • CDC Yellow Book: health information for international travel - high elevation travel & altitude illness
    • Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2019 update​
    More Guidelines
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