Internal and Emergency Medicine

, Volume 13, Issue 2, pp 223–229 | Cite as

Clinical chameleons: an emergency medicine focused review of carbon monoxide poisoning



Carbon monoxide (CO) is a colorless, odorless gas that is found in the environment, in the home, and in the human body as a normal part of mammalian metabolism. Poisoning from CO, a common exposure, is associated with significant morbidity and mortality if not recognized and treated in a timely manner. This review evaluates the signs and symptoms of CO poisoning, conditions that present similar to CO poisoning, and an approach to the recognition and management for CO poisoning. CO poisoning accounts for thousands of emergency department visits annually. If not promptly recognized and treated, it leads to significant morbidity and mortality. CO poisoning poses a challenge to the emergency physician because it classically presents with non-specific symptoms such as headache, dizziness, nausea, and vomiting. Due to nonspecific presentations, it is easily mistaken for other, more benign diagnoses such as viral infection. The use of specific historical clues such as exposure to non-conventional heat sources or suicide attempts in garages, as well as the use of targeted diagnostic testing with CO-oximetry, can confirm the diagnosis of CO poisoning. Once diagnosed, treatment options range from observation to the use of hyperbaric oxygen. CO poisoning is an elusive diagnosis. This review evaluates the signs and symptoms CO poisoning, common chameleons or mimics, and an approach to management of CO poisoning.


Carbon monoxide Headache Chameleon Vomiting Hyperbaric oxygen 



This manuscript did not utilize any grants, and it has not been presented in abstract form. This clinical review has not been published, it is not under consideration for publication elsewhere, its publication is approved by all authors and tacitly or explicitly by the responsible authorities where the work was carried out, and that, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright-holder. This review does not reflect the views or opinions of the U.S. Government, Department of Defense, U.S. Army, U.S. Air Force, or SAUSHEC EM Residency Program.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Statement of human and animal rights

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed consent



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Copyright information

© SIMI 2018

Authors and Affiliations

  • Patrick Chow Yuen Ng
    • 1
  • Brit Long
    • 2
  • Alex Koyfman
    • 3
  1. 1.Medical Toxicology, Rocky Mountain Poison and Drug CenterDenver Health and HospitalDenverUSA
  2. 2.Department of Emergency MedicineSan Antonio Military Medical CenterSan AntonioUSA
  3. 3.Department of Emergency MedicineUniversity of Texas Southwestern Medical CenterDallasUSA

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