What it is
Carbon monoxide (CO) is an odorless gas produced by faulty heaters, engines, generators, and fires. It binds to hemoglobin about 240 times more tightly than oxygen, silently suffocating the body from the inside. Survivors face a second threat: delayed neurological injury that can appear days to weeks later as memory problems, mood changes, or movement disorders.
How hyperbaric oxygen helps
Under pressure, oxygen physically outcompetes CO — clearing it from hemoglobin several times faster than breathing normal oxygen. Just as important, dissolved oxygen keeps the brain and heart supplied while the CO clears, and clinical evidence suggests HBOT reduces the risk of those delayed neurological effects.
What treatment looks like
Typically 1–3 sessions at 2.8–3.0 ATA beginning as soon as possible after exposure. Cases involving loss of consciousness, pregnancy, heart strain, or high CO levels are the clearest candidates.
- One of the most time-critical HBOT indications.
- Covered by Medicare and virtually all insurers as emergency care.
- If your CO detector goes off or you suspect exposure: fresh air, 911, then the chamber.
The evidence, honestly
Grade A — Strong Evidence
Supported by randomized trials and/or decades of consistent clinical results.
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Hyperbaric oxygen for carbon monoxide poisoning (Cochrane review)
Cochrane Database of Systematic Reviews · 2011 · meta analysis
Reviewing seven trials with conflicting results, the authors concluded existing evidence neither firmly establishes nor excludes benefit, reflecting the ongoing clinical debate.
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Hyperbaric oxygen for acute carbon monoxide poisoning
New England Journal of Medicine · 2002 · n=152 · rct
Randomized trial in which three HBOT sessions reduced the rate of cognitive sequelae at 6 weeks after acute CO poisoning compared with normobaric oxygen.
Common questions
I feel fine now — do I still need treatment?
Possibly. The danger with CO is delayed neurological injury appearing days or weeks later. HBOT is given partly to prevent exactly that, so get evaluated even if symptoms have eased.
How many sessions are needed?
Usually one to three, starting as soon as possible after exposure. Your treatment team decides based on exposure severity and symptoms.
Educational content, not medical advice — see our medical disclaimer. *Medicare coverage requires meeting clinical criteria; we verify yours for free. Last medically reviewed July 2026 by Dr. David Greene, MD.