A guide to carbon monoxide...

Carbon monoxide poisoning symptoms
from one-time exposure (acute CO poisoning)

Carbon monoxide poisoning symptoms from one time exposure (acute CO poisoning) can range from not feeling any symptoms at all to feeling major symptoms (but not knowing what's causing them) to death in minutes.

Carbon monoxide poisoning symptoms depend on the level of CO in the air, how long it is breathed, and a persons level of activity.

Many other factors play a role in the severity of symptoms, short term effectslong term effects, and the amount of carbon monoxide damage.

Carbon monoxide poisoning symptoms vary widely from person to person.

A person with mild symptoms may actually be severely poisoned.

Carbon monoxide reacts with hemoglobin (Hb) in red blood cells and forms carboxyhemoglobin (COHb). This is expressed as a percentage of red blood cells carrying carbon monoxide.


Generally does not cause symptoms but can cause some loss of coordination, tiredness, dizziness, and difficulty focusing in sensitive people


Mild frontal headache, nausea, vomiting, dizziness, loss of coordination, difficulty focusing


Headache, rapid heartbeat, confusion, lethargy, visual disturbances

All levels of exposure from this forward may lead to death as the victim loses motivation and ability to leave the danger zone (even in a fire)





50- 60%



Death in under 2 hours


Death in under 1 hour


Death in minutes


Low level carbon monoxide poisoning symptoms

  • Flu like symptoms

  • Food poisoning like symptoms

  • Headache

  • Brain fog and difficulty thinking

  • Problems focusing

  • Shortness of breath

  • Feeling of tightness across forehead

  • Throbbing in temples

  • Unexplained panic, anxiety, or sense of dread

  • Irritability/mood swings

  • Mild nausea

  • Unexplained claustrophobia

  • Unexplained sense that there is a presence or something is watching (many "ghost houses" have been found to have had carbon monoxide leaks)

Moderate carbon monoxide poisoning symptoms

  • Strong headache (sometimes described as different than a migraine, tension, or dehydration headache)

  • Dizziness

  • Nausea

  • Disorientation/confusion

  • Hallucinations

  • Increased rate of breathing

High level carbon monoxide poisoning symptoms

  • Vomiting

  • Abnormal heart beat

  • Convulsions/seizures

  • Lower body temperature

  • Shouting and incoherent behavior

Extreme carbon monoxide poisoning symptoms

  • Collapse

  • Seriously low blood pressure

  • Heart and respiratory failure

  • Unconsciousness

  • Coma

  • Death

A survivor may have a delayed reaction to carbon monoxide poisoning with additional [new] symptoms occurring in the weeks and months after exposure.

Carbon monoxide poisoning can cause all kinds of injury and damage resulting in a range of short term effects and long term effects.

Your comments about carbon monoxide poisoning...

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Questions? Want to share your opinion? Do it here...


I quit smoking about a year and a half ago and smoked a few cigarettes within the past 4 days (17 cigarettes in 4 days, to be exact - the pack says 6 mg CO, if that helps). I've had diarrhea (today, it was particularly bad), nausea and a very persistent, though mild, headache during these 4 days. The headache might be because of fatigue or the air-conditioning in the car, as I had a 4-hour journey 5 days ago and I'm not getting enough sleep, but I'm worried about the combination of diarrhea, nausea AND the headache. Do you think I might be suffering from mild CO poisoning? I've already thrown away the rest of the cigarette pack, as I freaked out reading that these may be symptoms of CO poisoning.

My question may seem ridiculous, but I'm worried because my body has been a "virgin" as regards smoking for a year and a half and I think it might be more sensitive.

Is not touching those stupid cigarettes again enough to get rid of a possible mild CO poisoning?

Thank you for any possible replies.

My child has brain damage
Angela from Michigan
My son was found face down unconcious on the floor at 3yrs old from carbon monoxide poisoning. No body at the hospital ever told us that there were long term effects or that there could be brain damage. My adorable 3yr old began to change and I didn\'t know why. He is 9 now and has had 3 mental hospitalizations and nightmare school experiences and today I found out it is because of brain damage caused by the monoxide poisoning. Why didn\'t they tell us this could happen?

steph from minnesota
since moving into my new apartment I was unaware of why I began having so many issues with my health.I would have systoms oh dizzyness lightheaded,Hallucinations,Nausea,Irritability/mood swings,Problems focusing,Food poisoning like symptoms
I just did'nt know what was going on with me until my boyfriend said I should check the carbon levels in the apartment and to my eyes my levels were extreamly elevated to the point we have to leave our apartment until further notice.

what are the sequences of carbon Monoxide
Tanique from Gallup
what are the sequences of events effects that happens starting from the early to late effects?

Could there be any permanant effects if my level was 16%?
Hello, Could there be any permanant effects if my carbon monoxide level was 16%?

David from Florida
Isn't one of the key signs of extreme CO poisoning
a reddish or pink flush.

the info really helped me understand and clearified that i have most likely been exposed thank you.

My experience of poisoning
martin telford from newcastle-upon-tyne England
Suffered levels of 19% (blood test taken after 1 hour of arrival at hospital) so could be close to 38%. thought I was going to die. I was at work breathing in CO from a flue which had been opened. The flue was off a burner used to heat 100 ton of lead. I collapsed unconscious and was given oxygen on the way to hospital. I am a keen 400m runner and have never ever managed to hit anywhere near the levels of performance I was at before the poisoning. Always short of information about CO I never realized it could have this effect until reading.

Carbon Monoxide Posioning!! :(
melissa from Spokane WA
Can u have only one of the syptoms to be diagnosed as carbon monoxide posioning?? or do u have to have all the syptoms? because my mother in law has a pellet stove and was just wondering because i have a little 4mth old and am concerned about her health! should i have a co detector installed in my house?

can doctors diagnose CO 3mths after the incident
tony morreale from manchester UK
I was rushed into hospital in nov 2010 after a collapse at home, i was found semi unconsious,and incoherant . the hospital thought i was drunk, but after being told i did not drink, i was admitted for being a stroke victim, i spent 5 days in hospital and no evidence of a stroke was found, so i was sent home, since then, my memory has been affected especially long term, my judgement impaired loss of weight and blurred vision, further hospital test show nothing, last week we had the gas appliances tested, they immediately found the gas fire to be dangerous and disconected, ( i live in rented accommadation,) Can doctors confirm CO poisong after 3mths

Darcy Niblo from denver colorado
I was poisoned about 6 months ago.And i have many symptoms that are listed.But the one that is the worst for me is im dizzy all the time. I have to walk with a cane or a walker.It get so bad i fell in the shower and fractured my hip. So i was woundering is being dizzy all the time a symptom?

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