Hyperbaric Oxygen Carbon Monoxide Poisoning Treatment

HBOT is FDA-cleared for carbon monoxide poisoning.

If you think you’ve been exposed to carbon monoxide, call 911 or go to the nearest emergency room immediately. Do not try to find a standalone HBOT clinic. Call Poison Control at 1-800-222-1222 for guidance.

Carbon monoxide (CO) poisoning is a medical emergency. It’s colorless, odorless, and fast-acting. HBOT is the most effective treatment for severe cases, but it only works if you get there in time.

For general information on how HBOT works, see our guide to hyperbaric oxygen therapy.

Why CO Poisoning Requires Fast Treatment

CO binds to hemoglobin about 200 times more readily than oxygen does. When you breathe CO, it rapidly displaces oxygen in your blood, forming a compound called carboxyhemoglobin (COHb). Your tissues start to suffocate.

But CO doesn’t just block oxygen delivery. It also damages mitochondria, the structures inside cells that produce energy. That damage can continue even after CO is cleared from the blood. That’s why speed matters so much.

Here’s how fast different treatments clear CO from your blood:

Room air: COHb half-life is about 5 hours
100% normobaric oxygen: half-life drops to 60 to 90 minutes
HBOT at 2.5 to 3 ATA: half-life drops to 20 to 30 minutes

That difference isn’t trivial. Faster CO clearance means less time for mitochondrial damage to accumulate. That may be the difference between full recovery and lasting neurological injury.

When HBOT Is Indicated

Not every CO poisoning case requires HBOT. Mild exposure without significant symptoms may be managed with standard high-flow oxygen. HBOT is indicated when the exposure is severe enough to carry real risk of lasting brain or heart damage.

Specialists typically recommend HBOT for any of the following:

Loss of consciousness at any point during or after exposure
COHb level above 25% (or above 15% in pregnant patients)
Neurological symptoms such as confusion, seizures, or focal neurological deficits
Cardiac involvement including ECG changes or elevated troponin
Pregnancy at any COHb level, because fetal hemoglobin binds CO more readily than adult hemoglobin

If you’re pregnant and have been exposed to CO, you need emergency evaluation regardless of how you feel. The fetus is at higher risk than you are.

What the Research Shows

The landmark study on HBOT for CO poisoning was published in the New England Journal of Medicine in 2002. Weaver et al. conducted a randomized controlled trial comparing HBOT to normobaric oxygen in patients with acute CO poisoning. The HBOT group had significantly reduced cognitive sequelae at six weeks. That means less memory loss, less confusion, and better overall brain function. (PMID: 12167682)

A 2011 Cochrane systematic review by Buckley et al. analyzed the broader body of evidence. The review found that while the evidence has limitations due to varying study designs, HBOT reduced the risk of delayed neurological sequelae compared to normobaric oxygen. (PMID: 21563127)

Delayed neurological sequelae is the medical term for the brain problems that can appear days or weeks after CO poisoning, even after the initial symptoms resolve. These can include memory problems, personality changes, and movement disorders. Preventing them is the main reason HBOT is used in serious cases.

What Treatment Looks Like

HBOT for CO poisoning happens in a hospital or hospital-affiliated hyperbaric unit, not a standalone wellness clinic. This is emergency medicine.

Most patients receive treatment at 2.5 to 3.0 ATA for 90 minutes. Depending on severity, one to three sessions is typical.

The treatment itself is straightforward. You breathe 100% oxygen inside a pressurized chamber. The elevated pressure allows far more oxygen to dissolve into plasma, bypassing the hemoglobin that CO has blocked.

The most important variable is time. Outcomes worsen with delays. If you or someone you know has signs of serious CO exposure, go to an emergency room. The ER team will contact a hyperbaric medicine physician to determine if HBOT is indicated.

Don’t search for a nearby HBOT clinic. Contact Poison Control at 1-800-222-1222 or call 911.

You can read more about HBOT costs and what to expect from treatment in our HBOT cost guide.

Frequently Asked Questions

Should all CO poisoning patients get HBOT?

No. Mild cases without neurological symptoms, loss of consciousness, or high COHb levels may be managed with normobaric oxygen in the emergency department. A hyperbaric medicine specialist makes the call based on your clinical picture.

How quickly does HBOT work for CO poisoning?

HBOT reduces the COHb half-life to about 20 to 30 minutes, compared to 5 hours breathing room air. That rapid clearance may prevent long-term brain damage by limiting the window during which CO damages mitochondria.

What are the long-term effects of CO poisoning?

Without adequate treatment, CO poisoning can cause delayed neurological sequelae weeks after exposure. These include memory problems, personality changes, difficulty concentrating, and in some cases parkinsonism. The Weaver et al. 2002 study showed HBOT significantly reduces this risk.

Where do I get HBOT for CO poisoning?

Go to an emergency department. Hospital emergency rooms with affiliated hyperbaric units are the right setting for this treatment. Call Poison Control at 1-800-222-1222 for immediate guidance on where to go.

References

Weaver LK, et al. Hyperbaric Oxygen for Acute Carbon Monoxide Poisoning. N Engl J Med. 2002;347(14):1057-1067. PMID: 12167682
Buckley NA, et al. Hyperbaric oxygen for carbon monoxide poisoning. Cochrane Database Syst Rev. 2011. PMID: 21563127

Medical Disclaimer: This page is for informational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before pursuing any medical treatment.