Carbon monoxide poisoning

Last reviewed: 22 Feb 2023
Last updated: 06 Jul 2020



History and exam

Key diagnostic factors

  • risk of carbon monoxide exposure
  • headache
  • nausea
  • vomiting
  • vertigo
  • altered consciousness
  • dizziness
  • dyspnoea
  • pain
  • sleep changes
  • emotional lability
Full details

Other diagnostic factors

  • delayed neuropsychiatric features
  • other severe neurological symptoms
  • focal neurological abnormalities
Full details

Risk factors

  • exposure to incomplete combustion of carbon-containing material
  • exposure to methylene chloride
Full details

Diagnostic investigations

1st investigations to order

  • blood gas analysis
  • 12-lead ECG
  • blood pressure
  • cardiac monitoring
  • glucose
  • full blood count
  • urea and electrolytes
  • troponin
  • creatine kinase
Full details

Investigations to consider

  • mini-mental state examination
  • CT head
  • magnetic resonance spectroscopy
  • chest x-ray
  • liver function tests
Full details

Treatment algorithm


all patients


Expert advisers

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

Flight Doctor

Greater Sydney Area Helicopter Emergency Medical Service




AA declares that he has no competing interests.


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

Jason J Rose, MD, MBA

Assistant Professor of Medicine and Biomedical Engineering

University of Pittsburgh



Disclosures: JJR is a co-inventor on patent applications for the use of heme-based molecules as antidotes for CO poisoning. JJR is a shareholder, officer, and director of Globin Solutions, Inc. Globin Solutions, Inc. has an exclusive license to this technology. Globin Solutions, Inc. had an option agreement to technology directed at using hydroxycobalamin for CO poisoning from Virginia Commonwealth University in the last 12 months. JJR is an author of publications cited within this topic.

Peer reviewers

Robert Taylor, MBChB, MRCP(UK), MRCP(London), DipMedTox, DipTher PGDME, FHEA FRCEM

Acute Hospital Sub Dean (Cornwall)

Honorary Clinical Senior Lecturer

Consultant Emergency Physician

University of Exeter Medical School

Royal Cornwall Hospitals NHS trust




RT declares that he has no competing interests.


Emma Quigley

Section Editor, BMJ Best Practice


EQ declares that she has no competing interests.

Tannaz Aliabadi-Oglesby

Lead Section Editor, BMJ Best Practice


TAO declares that she has no competing interests.

Julie Costello

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

Adam Mitchell

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

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