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Patient education: Carbon monoxide (CO) poisoning (The Basics)
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Patient education: Carbon monoxide (CO) poisoning (The Basics)
Written by the doctors and editors at UpToDate
All topics are updated as new evidence becomes available and our peer review process is complete.
Literature review current through: Nov 2017. | This topic last updated: Sep 29, 2017.

What is carbon monoxide? — Carbon monoxide (CO) is a kind of gas. You can't see, smell, taste, or feel it. When fuels such as gasoline, natural gas, wood, or charcoal burn, they make CO. Exhaust fumes from cars and trucks, stoves, gas ranges, generators, and heating systems have CO in them.

What is CO poisoning? — CO poisoning happens if you breathe too much CO. It causes headaches and can make you pass out. It can even kill you.

How do people get CO poisoning? — People can get CO poisoning if they breathe high levels of CO inside a closed space where fresh air can't get in. Common sources of CO poisoning include:

Smoke from a fire

A gas or oil furnace that is not working correctly

Kerosene heaters, charcoal grills, camping stoves, and gas-powered electric generators

Cars or other vehicles that are left running inside indoor skating rinks, warehouses, and parking garages

What are the symptoms of CO poisoning? — The symptoms of CO poisoning can seem like the flu but without the fever. They include:


Confusion or dizziness

Feeling very tired

Feeling sick to your stomach (nausea)

If you or someone you are with gets these symptoms and might have been around CO, move to a place with fresh air right away and call for an ambulance (in the US and Canada, dial 9-1-1).

Breathing very high amounts of CO can cause:

Seizures – These are waves of abnormal electrical activity in the brain that can make you move or behave strangely, or pass out.


Is there a test for CO poisoning? — Yes. Your doctor or nurse should be able to tell if you have it by learning about your symptoms and doing an exam. You also will need a blood test to check for CO in your body.

How is CO poisoning treated? — People with CO poisoning are treated in the hospital with oxygen. The oxygen can be given different ways, including:

A mask placed over the nose and mouth

A ventilator – This is a machine that helps you breathe through a tube that goes down your throat.

A hyperbaric oxygen chamber – This is a full-body chamber with high pressure inside that helps oxygen get into your body more quickly.

Can CO poisoning be prevented? — To reduce your chances of CO poisoning:

Put a CO detector in your home. This is a device that is like a smoke alarm. If you plug the detector into an electrical outlet, make sure it also has a battery back-up.

Make sure that all the appliances in your home are working correctly.

Have your heating system (including all chimneys and vents) checked to make sure it is working correctly.

Never leave a car running in a garage, even with the garage door open.

Never run a generator inside your house or garage or just outside a window, door or vent that goes into your house.

Never use a charcoal grill or portable propane grill indoors.

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Topic 86018 Version 6.0

All topics are updated as new information becomes available. Our peer review process typically takes one to six weeks depending on the issue.