Carbon Monoxide Poisoning
Informed by recognized medical guidance
Overview
Carbon monoxide (CO) poisoning happens when you breathe in too much of a colorless, odorless gas called carbon monoxide. It can make you very ill because it stops your blood from carrying oxygen to your brain, heart, and other organs.
Key facts
- Carbon monoxide has no taste, smell, or color, so you cannot tell it is in the air.
- It is produced by burning fuels like gas, wood, coal, oil, or charcoal when there is not enough air.
- Early symptoms can feel like flu, but without a fever.
- Breathing in high levels can be deadly, so it is a medical emergency.
It is not rare, but many mild cases go unrecognized. It is more common in winter months when people use heaters and keep windows closed.
Anyone can be affected, but it is most dangerous for unborn babies, infants, older adults, and people with heart or lung conditions.
Symptoms
- Loss of consciousness or passing out
- Seizure
- Severe confusion or inability to think clearly
- Difficulty breathing or feeling like you cannot get air
- Chest pain or irregular heartbeat
- Lips or skin appearing bright pink or cherry red (though this can be hard to see)
- Any symptoms while sleeping in a room with a fuel-burning appliance, or after using a fuel-burning device indoors
- ⚠Persistent headache, dizziness, or nausea that improves when you leave the building
- ⚠Feeling very tired for no reason
- ⚠Flu-like symptoms without a fever
- ⚠People in the same building having similar symptoms
Common symptoms
- Dull headache
- Dizziness
- Feeling sick (nausea) or being sick (vomiting)
- Tiredness and confusion
- Stomach pain
- Shortness of breath
Symptoms in children
- Irritability or unusual behavior
- Refusing to eat or poor feeding
- Tiredness or drowsiness
- Flu-like symptoms without a fever
Symptoms in older adults
- Worsening confusion or memory problems
- Falls or unsteadiness
- Chest pain or worsening heart failure
- Flu-like symptoms without a fever
Causes
Main causes
- Burning fuel in an enclosed or poorly ventilated space, such as a running car in a garage, a faulty gas boiler, a blocked chimney, or a portable generator indoors.
- Burning charcoal, wood, or gas in poorly ventilated areas.
- Blocked flues or chimneys that prevent smoke and gases from escaping.
- Faulty or poorly maintained appliances: gas ovens, water heaters, fireplaces, and central heating boilers.
- Using a generator or fuel-burning engine inside the home, garage, caravan, or tent.
Risk factors
- Living in a house with fuel-burning appliances that are not regularly serviced.
- Using portable heaters, gas stoves, or generators indoors.
- Sleeping in a room with a faulty gas appliance or unvented paraffin heater.
- Working in professions such as firefighting, vehicle repair, welding, or operating forklifts.
- Living in an older home with poor ventilation.
When to see a doctor
See a doctor urgently if:
- If you have any of the emergency symptoms listed above, call your local emergency number straight away.
- If you feel unwell after a fuel-burning appliance might have been left on, or was used in a closed space.
Book a routine appointment if:
- If you have a mild headache, dizziness, or nausea that does not go away, especially if someone else in your home feels the same way.
- If you suspect a gas leak or carbon monoxide in your home and want advice.
Diagnosis
A doctor will ask about your symptoms, when they started, and whether any fuel-burning appliances are involved. They may test a small sample of your blood, or use a device to measure the carbon monoxide level in your breath.
Tests that may be done
- Blood test (or pulse oximeter reading) to measure oxygen and carbon monoxide levels in your blood.
- Breath test using a hand-held monitor.
- In an emergency, a blood sample from an artery (arterial blood gas) to check carbon monoxide levels.
What to expect at your appointment
The doctor will also check for signs that your brain or heart may have been affected. If they suspect significant poisoning, they may arrange a hospital assessment, including oxygen therapy. You may be asked to switch off appliances and ventilate your home.
Treatment
The main treatment is to get you into fresh air immediately. At the hospital, you may be given additional oxygen to help remove carbon monoxide from your blood more quickly. In severe cases, a special oxygen chamber (hyperbaric oxygen therapy) may be considered, but most people do not need this.
Self-care at home
- Leave the area where you think the leak is and go outside into fresh air.
- Open doors and windows to ventilate the space, but only if it is safe to do so.
- Switch off the appliance that may be causing the leak, if you can do so without risking your safety.
- Call your local emergency number if anyone is unwell or has collapsed.
- Do not go back into the building until it has been checked by a qualified engineer.
Medical treatments
In hospital, you will be given high-flow oxygen through a face mask. This helps your blood release carbon monoxide faster. The length of time you need oxygen depends on your symptoms and blood levels. Healthcare staff will monitor you until you are safe. In some cases, hyperbaric oxygen therapy may be offered, but this is not routine for everyone.
When is surgery considered?
Surgery is not used for carbon monoxide poisoning.
Living with this condition
After mild poisoning, you may still feel tired or have headaches for a few days. In more severe cases, some people notice memory problems, mood changes, or difficulty concentrating. These usually improve over time but can take weeks or months.
Lifestyle tips
- Have your fuel-burning appliances serviced by a registered engineer at least once a year.
- Fit a carbon monoxide alarm in your home and check it regularly.
- Never run a car, generator, or grill in an enclosed space like a garage or tent.
- Ventilate rooms where a fire or heater is used.
Diet and exercise
Eat a balanced diet and stay as active as you feel able. Rest is important after carbon monoxide exposure. If you feel breathless or unwell during activity, talk to your doctor before increasing it.
Mental health and emotional wellbeing
A scare like this can leave you feeling anxious or worried, especially if it happened in your home. It is normal to feel jumpy for a while. If these feelings do not ease, tell your doctor. You can also talk to a trusted friend or family member, and in an emergency, contact a crisis support service.
Prevention
Yes, carbon monoxide poisoning is almost entirely preventable. The most important steps are installing a carbon monoxide alarm, servicing fuel-burning appliances regularly, and never using fuel-burning equipment indoors.
Screening programmes
There is no routine screening test for carbon monoxide poisoning. The best approach is prevention, plus being alert to the symptoms.
Complications
If left untreated
- Brain damage, which can cause lasting problems with memory, thinking, and coordination.
- Heart problems, including chest pain, irregular heartbeat, or heart attack.
- Death in severe cases.
- Long-term neurological problems such as Parkinson-like symptoms.
- Damage to an unborn baby if the mother is exposed.
Long-term outlook
With prompt treatment, many people recover completely. Even people with more severe poisoning often improve with time, though some may have long-term symptoms. The key is not to delay seeking help.
Find support
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Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
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Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: August 14, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.
Guidance may differ by country or region. Confirm local recommendations with a qualified healthcare provider.