What is carbon monoxide poisoning?

Carbon monoxide (CO) poisoning is a life-threatening emergency. It occurs from breathing in (inhaling) carbon monoxide fumes.

What causes carbon monoxide poisoning?

CO is a colorless, odorless, tasteless gas made when fuel burns. Fuels include wood, gasoline, coal, natural gas, or kerosene. Breathing in CO fumes prevents the body from using oxygen correctly. This can harm the brain, heart, and other organs. People with health problems, such as heart and lung disease, are at greater risk for harm. Infants, children, pregnant people, and older adults are also at greater risk.

Most CO exposures happen in the winter in cold climates. A very common source of CO poisoning is unvented, fuel-burning space heaters in the home. This type of space heater uses indoor air and fuels like kerosene or natural gas for the heating process. It vents the gases it makes into the room, instead of outdoors. A space heater that is not installed right or not working right can release CO and other toxic fumes into the room. This uses up much of the oxygen in the room.

Newer models have sensors that shut off the heater when the oxygen level in the room falls too low. Older models don't have this safety feature. So some states ban unvented space heaters.

Other common sources of CO are:

• Fires.

• Car exhaust or idling vehicles.

• Gas or oil water heaters that aren't working right.

• Oil, wood, gas, or coal furnaces that aren't working right.

• Gas clothes dryers that aren't working right.

• Clogged chimneys.

• Wood-burning fireplaces or gas log burners.

• Cooking appliances that aren't working right.

• Gas- or fuel-burning appliances in cabins or campers, barbecue grills, pool or spa heaters, or ceiling-mounted heating units.

• Generators that run on gasoline.

• Open air exposure to motorboat exhaust.

• Tobacco smoke.

What are the symptoms of carbon monoxide poisoning?

The most common symptoms of CO poisoning include:

• Headache.

• Dizziness.

• Weakness.

• Nausea and vomiting.

• Rapid heartbeat.

• Shortness of breath.

• Seizures.

• Chest pain.

• Cardiac arrest.

• Loss of hearing.

• Blurry vision.

• Confusion.

• Loss of consciousness or coma.

• Respiratory failure.

• Death.

Many of these symptoms can look like those of other health problems, such as the flu or food poisoning. Always see your doctor for a diagnosis.

How is carbon monoxide poisoning diagnosed?

Health care providers can often diagnose CO poisoning based on a known exposure to CO fumes. You may also have a blood test to check for CO in your blood. A physical exam may show changes in mental status. You may also have chest X-ray, heart, and neurological tests.

How is carbon monoxide poisoning treated?

If you or anyone with you has symptoms of CO poisoning, stay calm but act quickly:

• Leave the area and get fresh air right away. If you are indoors, go outside.

• Turn off the CO source, but only if you can do so quickly and safely without putting yourself or others in danger.

• Call 911 or your local emergency medical service (EMS).

• If someone has stopped breathing, get the person to fresh air right away. Start CPR. Don't stop until they are breathing on their own, someone else can take over, or you can't keep going due to safety or fatigue.

A doctor will decide what other treatment is needed. Treatment must be started right away. Emergency care may include oxygen therapy. In serious cases, hyperbaric oxygen may be used.  

What are possible complications of carbon monoxide poisoning?

CO poisoning is life-threatening. It can cause death. Brain damage can also result if the brain is without oxygen for too long.

How can you prevent carbon monoxide poisoning?

These important steps can help protect against CO poisoning:

• Have your furnace and fireplace cleaned and checked before each heating season.

• Only use fuel-burning space heaters in well-ventilated areas. Electrical space heaters pose no danger of CO poisoning, unlike those that burn fuels, such as kerosene or natural gas.

• Don't leave cars, trucks, or other vehicles running in an enclosed area, such as a garage, even with the outside door open.

• Don't use portable heaters or lanterns while sleeping in enclosed areas, such as tents, campers, or other vehicles. This is even more important at high altitudes, where the risk of CO poisoning is increased.

• Never use a gas stove or oven to heat a room.

• When using a gas-powered generator for electricity, be sure to keep it a safe distance away from the home.

• Install battery backup CO detectors in your home to warn you if CO levels begin to rise. 

Key points about carbon monoxide poisoning

• CO poisoning occurs when you breathe in CO fumes. The CO prevents the body from using oxygen correctly.

• Most CO exposures happen in the winter. A common source is unvented space heaters.

• Symptoms of CO poisoning include headache, dizziness, weakness, nausea and vomiting, rapid heartbeat, shortness of breath, seizures, chest pain, confusion, and loss of consciousness.

• CO poisoning needs to be treated right away by getting outside to fresh air and calling 911.

• To prevent CO poisoning, use battery backup CO detectors and make sure that your fireplace and heaters are working correctly.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.