Cyanide Poisoning

H yperbaric Oxygen Therapy Approval Status

Yes Clearance by US Food and Drug Administration (FDA)

Yes Approval by the Undersea and Hyperbaric Medical Society (UHMS)

About Clearance and Approval


Definition and Causes

Cyanide is a rapidly acting and deadly chemical. Smelling of bitter almonds or entirely odorless, cyanide may take the form of a colorless gas, a liquid, or a crystal powder. Cyanide, like carbon monoxide (CO), binds to hemoglobin in red blood cells and blocks their capacity to carry oxygen to cells and tissues.

Many plants, foods, and microbes produce harmless cyanides, and for decades cyanides have been used safely in manufacturing. Cigarette smoke contains traces of cyanide. Cyanide has also been used as an agent of chemical warfare and domestic terrorism. But from day to day cyanide poisoning most often affects firefighters and other victims of fire involving smoke inhalation, as the combustion of plastics, textiles, and other synthetic materials produces a highly toxic mix of cyanide and carbon monoxide.

Inhaling even small amounts of fire smoke can be fatal. Serious neurological effects may be delayed days or weeks after acute poisoning. Chronic exposure may cause persistent headaches, dizziness, nausea, and permanent neurological damage. Smoke inhalation may be further complicated by airborne particles and by burns to the throat and lungs.

Evidence Index

FDA cleared, widely reimbursed
Strong body of evidence
Repeatedly favorable results
Early or mixed results
Unfavorable or no evidence
Strong evidence against HBOT

Treatment with Hyperbaric Oxygen Therapy

Hyperbaric oxygen therapy (HBOT) is indicated for the emergency treatment of carbon monoxide poisoning complicated by cyanide poisoning after smoke inhalation. Hyperbaric oxygen is also an adjunctive therapy for pure cyanide poisoning in patients who do not respond to cyanide antidotes. HBOT dissolves additional oxygen in the blood plasma and has been shown to work effectively alone and in combination with hydroxocobalamin (Cyanokit) and other cyanide antidote kits.

Read the Cyanide Poisoning page in the Undersea and Hyperbaric Medical Society resource library to learn more about cyanide poisoning, the rationale for hyperbaric oxygen therapy, and key clinical evidence, outcomes, and success factors.

HyperbaricLink Commentary

The emergency treatment of smoke inhalation offers perhaps the single best reason for the healthcare community to demand 24/7 access to hyperbaric chambers across the US. Cyanide, carbon monoxide, inhaled particulates, and thermal injuries together require speedy action to save the lives of firefighters and other fire victims. The clinical evidence for hyperbaric oxygen may not be as strong for nonfire cyanide poisoning as for nonfire carbon monoxide poisoning, but the benefits of oxygen are well established. As Medscape puts it:

Oxygen and sodium thiosulfate are the most widely accepted cyanide antidotes… The mechanism of action of oxygen as a cyanide antidote is unclear, but it potentiates the effect of other antidotes. When used in the setting of smoke inhalation, it is also therapeutic for CO poisoning. Thus, high concentrations of oxygen should be promptly delivered. Smoke Inhalation Injury, Medscape, 22 Aug 2014

Ongoing surveillance projects and prospective trials may bolster the clinical case for hyperbaric oxygen therapy in the routine treatment of smoke inhalation.

Patient Resources

HyperbaricLink recommends the following websites for anyone seeking authoritative information, patient advocacy, and community support for cyanide poisoning.

American Association of Poison Control Centers (AAPCC)

The AAPCC is a nonprofit organization representing 57 poison centers staffed by pharmacists, physicians, nurses, and toxicology specialists who provide free, private, expert medical advice 24/7/365.

National Fire Protection Association (NFPA)

A leading authority on fire, electrical, and building safety, the NFPA provides free PDF downloads with excellent carbon monoxide safety tips and CO detector guidelines. Preventing building fires is an effective way of reducing the number of cases of cyanide poisoning.

US Department of Homeland Security (DHS)

The DHS website includes the informative: Chemical Attack Fact Sheet: Warfare Agents, Industrial Chemicals, and Toxins [PDF] which covers signs, symptoms, and first aid for chemical weapons based on cyanide and other chemicals.

Clinical Resources

Start with the following resources to explore current research activities and the peer-reviewed medical literature on hyperbaric oxygen therapy for cyanide poisoning.

 Use the search buttons below to go directly to research on hyperbaric oxygen therapy.
US National Institutes of Health keeps the official list of human clinical trials currently enrolling, in progress, and recently completed. One may reasonably question the size and legitimacy of any study not listed here.


Google Scholar

A specialized Google search engine, Google Scholar indexes scholarly articles, patents, and legal opinions and journals. Google Scholar may produce many search results, but entries provide easy access to full-text journal articles.

Search Google Scholar


A service of WebMD, Medscape offers specialists, primary care physicians, and other health professionals robust and integrated medical information and educational tools. The website devotes several well-referenced paragraphs to hyperbaric oxygen therapy under Emergency Department Care for smoke inhalation.

National Institute for Occupational Safety and Health (NIOSH)
US Centers for Disease Control and Prevention (CDC)

The CDC is dedicated to protecting health and promoting quality of life through the prevention and control of disease, injury, and disability. Its programs reduce the health and economic consequences of the leading causes of death and disability. NIOSH offers a free Pocket Guide to Chemical Hazards with key information about cyanides and other chemical hazards in the work environment.
US National Library of Medicine, US National Institutes of Health

PubMed keeps the official list of scientific papers published in reputable peer-reviewed medical journals. One may reasonably question the importance and legitimacy of any study not listed here.



News About Cyanide Poisoning and Hyperbaric Oxygen Therapy

More news from O2.0 – the HyperbaricLink blog

Complete cyanide news archive from O2.0 — the HyperbaricLink blog

Further Reading

HyperbaricLink suggests "A Bitter Pill" by Joy Bergmann in the Chicago Reader, 2 Nov 2000.

Related Terms

  • Asphyxiation
  • Carbon monoxide (CO) poisoning
  • Chemical terrorism
  • Chemical warfare
  • Cyanide antidote kit (CAK)
  • Cyanogen chloride (CNCl) (CK)
  • Emergency medical services (EMS)
  • Emergency medical technician (EMT)
  • Fire
  • Firefighter
  • Hydrogen cyanide (HCN) (AC)
  • Hydroxocobalamin (Cyanokit)
  • Paramedic
  • Potassium cyanide (KCN)
  • Smoke inhalation
  • Sodium cyanide (NaCN)
  • Sodium thiosulfate
  • Suicide
  • Terrorism
  • Vitamin B12


Undersea and Hyperbaric Medical Society, Indications, Cyanide Poisoning. Retrieved 02 May 2015.
Facts About Cyanide, Centers for Disease Control and Prevention (CDC). Retrieved 27 November 2011.
Page Data
Updated: 25 Jul 2015 05:46 PM
Created: 28 Nov 2011 02:35 PM
By: About the authors »