Carbon Monoxide Poisoning

Carbon monoxide poisoning is a life-threatening complication of breathing in carbon monoxide (CO) fumes. CO fumes form when natural fuels burn. Symptoms of carbon monoxide poisoning include nausea and shortness of breath. You can prevent carbon monoxide poising by installing a CO detector.


What is carbon monoxide poisoning?

Carbon monoxide poisoning is a life-threatening illness that happens after breathing in fumes that contain carbon monoxide (CO). When high levels of CO enter your body, it can be deadly after only a few minutes. The most common symptoms of CO poisoning are a headache and shortness of breath. Contact emergency services immediately if you suspect you have CO exposure.

What is carbon monoxide?

Carbon monoxide is an invisible, colorless and odorless gas produced when gasoline and other fuels burn (combustion). You can’t smell or taste it. CO can build up quickly and is dangerous at high levels.

Where does carbon monoxide come from?

Carbon monoxide is a byproduct of burning or the process of combustion. It’s made from:

  • Car and truck engines.
  • Small gasoline engines.
  • Fuel-burning space heaters (not electric).
  • Gas stoves or ranges.
  • Grills.
  • Lanterns.
  • Heating systems, including home furnaces.
  • Burning charcoal, kerosene, propane or wood.

How long does it take to get carbon monoxide poisoning?

In high concentrations of carbon monoxide, it can take fewer than five minutes to get carbon monoxide poisoning. Under lower concentrations, it can take an hour to two hours to cause poisoning.

How common is carbon monoxide poisoning?

Each year in the United States, accidental carbon monoxide poisoning kills more than 400 people. Carbon monoxide poisoning also sends an additional 100,000 people to emergency rooms annually.


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Symptoms and Causes

What are the signs and symptoms of carbon monoxide poisoning?

Early warning signs of carbon monoxide poisoning include:

Moderate exposure to carbon monoxide can cause the following symptoms:

If you notice any warning signs or symptoms, go outside immediately and contact 911 or your local emergency services number. Don’t stay indoors to call for help. If you’re unable to get outdoors safely, open a window or door and stay by the open window or door while calling for help.

Can you have delayed symptoms of carbon monoxide poisoning?

At low levels, carbon monoxide fumes may cause symptoms that don’t take an immediate effect on your body. These fumes are still toxic and can cause serious harm to your body the longer you breathe them in. Contact emergency services if you suspect you have exposure to carbon monoxide.

What causes carbon monoxide poisoning?

Inhaling carbon monoxide fumes causes carbon monoxide poisoning. When inside your lungs, carbon monoxide can prevent oxygen from reaching your bloodstream.

Many appliances and vehicles burn fuel and emit (release) carbon monoxide. When people use and maintain these appliances correctly, the CO levels usually aren’t harmful. CO poisoning happens when fuel-burning appliances run without proper ventilation. For example, it can be dangerous if you:

  • Let your car or truck idle in an enclosed space, like a garage.
  • Have a vehicle with a blocked exhaust system, such as by snow in the tailpipe.
  • Use a kerosene heater or gas barbecue grill indoors.

What happens to your body during carbon monoxide poisoning?

Red blood cells carry oxygen throughout your body. Your organs need oxygen to function. But red blood cells take in carbon monoxide faster than oxygen. High levels of carbon monoxide exposure cause CO to crowd out oxygen in your bloodstream.

If you breathe too much CO, organs such as your brain and heart don’t get enough oxygen. CO can also combine with proteins in your body and damage your cells and organs. If you inhale a lot of CO, you can lose consciousness (pass out) and suffocate within minutes.


What are the risk factors for carbon monoxide poisoning?

Everyone is at risk for carbon monoxide poisoning. In the winter, risks are higher because of frequently used heating systems. Those who are at the highest risk of CO poisoning at low doses of exposure include:

  • Developing fetuses.
  • Infants.
  • Adults over age 65.
  • People living at high altitudes.
  • People with chronic heart disease, anemia or respiratory (breathing) issues.
  • People who smoke tobacco products.

People who have a small body size, as well as pets and animals, may see the effects of CO poisoning sooner. Pets are usually the first in a household to show symptoms.

You may be more at risk of CO poisoning if you work in an environment where there are combustion engines or fires. Harmful CO levels exist in places such as boiler rooms, warehouses or petroleum refineries. The following careers may put you more at risk of CO poisoning:

  • Firefighters.
  • Mechanics.
  • Drivers.
  • Welders.

What are the complications of carbon monoxide poisoning?

Carbon monoxide poisoning is life-threatening. After only a few minutes of exposure, it can be deadly. If you catch CO poisoning in time, treatment can reverse the effects. You may experience lingering complications to your health after CO poisoning like:

In addition, carbon monoxide poisoning can affect a pregnant person and lead to miscarriage or abnormal fetal development.


Diagnosis and Tests

How is carbon monoxide poisoning diagnosed?

A healthcare provider will diagnose carbon monoxide poisoning after exposure by performing a blood test. They’ll remove a small sample of your blood and test it for CO. In addition, they may check your heart rate and oxygen levels through a finger oximeter. This device goes over your fingertip to take a reading.

Your provider will learn more about your health by taking a complete medical history. They’ll also ask you about your exposure to CO, like the length of time and location where you had exposure. These questions can help them understand how much CO possibly entered your body.

Management and Treatment

How is carbon monoxide poisoning treated?

Treatment for carbon monoxide poisoning is breathing in pure oxygen. A healthcare provider will give you an oxygen mask to breathe through. This will offset the carbon monoxide buildup in your body.

If you suspect you have carbon monoxide exposure or poisoning, call 911 or your local emergency services number and go outdoors immediately to wait for help. If it’s unsafe for you to go outdoors, open a door or window and stay close to it so you breathe in fresh air rather than carbon monoxide fumes.

Can I treat carbon monoxide poisoning at home?

You shouldn’t try to treat carbon monoxide poisoning on your own at home. If you think you had carbon monoxide exposure or poisoning, contact emergency services immediately. A healthcare provider can monitor your body’s oxygen levels to make sure you don’t have any long-term complications caused by exposure to the fumes.

If you have carbon monoxide in your home, go outside to get fresh air immediately. Don’t reenter your home until local emergency services tell you it’s safe to do so. There still may be CO fumes in your home. A qualified professional can check your appliances to make sure your home has proper ventilation and that all appliances are working safely, as intended. Install a carbon monoxide detector so it can alert you if you have a CO leak.

How long does carbon monoxide poisoning last?

For mild carbon monoxide poisoning symptoms, you may notice they go away or reduce shortly after moving into an area with fresh air or breathing in pure oxygen through a mask. It could take up to 24 hours for CO to leave your body, so your symptoms may persist during this time. You may also experience lingering symptoms for up to two weeks after exposure to CO.


Can carbon monoxide poisoning be prevented?

The following can help you prevent carbon monoxide poisoning:

Do a yearly inspection

At the beginning of each heating season, hire a trained professional to inspect fuel-burning appliances in your home, including:

  • Oil and gas furnaces.
  • Gas water heaters.
  • Gas ranges and ovens.
  • Gas dryers.
  • Gas or kerosene space heaters.
  • Fireplaces.
  • Wood stoves.
  • Flues and chimneys (check for blockages and cracking).

Choose and use appliances wisely

If you have fuel-burning appliances, take the following precautions:

  • Choose appliances that vent fumes to the outside. They should be properly installed and maintained.
  • Buy gas equipment that carries the seal of a national testing agency.
  • Follow instructions for any fuel-burning appliance.
  • Use the right fuel for any unvented gas or kerosene space heaters. Open the doors and crack a window in the rest of the home.
  • Call an expert to inspect your gas appliances if you suspect something isn’t working properly.
  • Never use a gas oven or clothes dryer as a heating source.
  • Never sleep in a room with an unvented kerosene or gas space heater.

Install a carbon monoxide detector

Install a battery-operated (or battery backup) carbon monoxide detector in your home. You should:

  • Test the CO detector when you change the clocks twice a year to make sure it’s still in good working condition. Replace the detector every five years.
  • Change the batteries in the detector regularly or every six months.
  • Place the detector in a place where you’ll hear it if the alarm sounds.

Ventilate your workspace

If you work in an environment where there are high levels of carbon monoxide, wear safety equipment, like a respirator, and make sure the area where you work has proper ventilation. Where you have ventilation, make sure the area in front of a vent is clear of debris or blockages that can prevent proper airflow.

If you suspect carbon monoxide exposure or you have symptoms of carbon monoxide poisoning, exit the area immediately and seek fresh air while calling emergency services.

How can I lower my risk of carbon monoxide poisoning?

To lower your risk of carbon monoxide poisoning, avoid the following:

  • Idling a car or truck inside of a garage, even if the garage door is open. Fumes build up quickly and can even seep into your home if it’s attached to the garage.
  • Using a charcoal or gas grill indoors.
  • Using small, gasoline-powered engines in enclosed spaces. These include lawnmowers, power washers, weed trimmers, snow blowers, chainsaws or generators.

Outlook / Prognosis

Is carbon monoxide poisoning fatal?

Yes, carbon monoxide poisoning can be fatal. If you inhale a lot of CO fumes, it can be deadly within minutes of entering your body. Get to fresh air and call emergency services if you suspect you have CO exposure or poisoning.

A person who’s sleeping can sometimes die before experiencing any symptoms. It’s important to have working CO detectors in your home to notify you of these toxic fumes if you’re sleeping.

What’s the outlook for carbon monoxide poisoning?

Your outlook depends on how much and for how long you had exposure to carbon monoxide. Prompt treatment can reverse the effects of CO poisoning. However, there’s a risk of permanent damage to your brain and heart, which need a lot of oxygen.

Living With

How do I take care of myself?

Install a carbon monoxide detector in your home. This detector looks similar to a smoke detector, or it can be combined with a smoke detector. If you have CO in your home, an alarm will sound. When you hear the alarm:

  • Don’t try to find the source of the gas.
  • Move outside immediately.
  • Call 911 or local emergency services.
  • Account for everyone in your house.
  • Don’t reenter your home until emergency responders say it’s safe to do so.

When should I go to the ER?

Contact emergency services if you suspect you have carbon monoxide exposure or poisoning. Get to a safe area outside (in fresh air) when you call for help.

What questions should I ask my provider?

If you received treatment for carbon monoxide poisoning, ask your healthcare provider:

  • Is the damage permanent, or will the effects go away over time?
  • Will I need follow-up care?
  • How can I prevent CO poisoning?
  • Do I need any long-term treatment?
  • Are there any effects on my reproductive system or fertility?

Additional Common Questions

What’s the difference between carbon monoxide and carbon dioxide?

Carbon monoxide (CO) is a compound made of one carbon atom bonded to one oxygen atom. Carbon monoxide doesn’t naturally form in Earth’s atmosphere. It forms when certain components burn (combustion). Oxygen is a key component of combustion, in addition to fuels like oil and natural gas. When the oxygen level is low in an area where something’s burning, carbon monoxide forms as a byproduct of the chemical reaction.

Carbon dioxide (CO2) is a compound made of one carbon atom bonded to two oxygen atoms. Carbon dioxide forms naturally in our environment. When you breathe in oxygen, your body releases carbon dioxide.

CO is toxic. It can cause death if you breathe it in at high concentrations.

CO2 isn’t considered toxic but it can pose health hazards at large concentrations.

A note from Cleveland Clinic

Carbon monoxide (CO) poisoning can become deadly in a matter of minutes. If you suspect CO poisoning, leave your home or building immediately and call 911 or your local emergency services number. If treated quickly, you may be able to reverse the effects of CO poisoning.

The best way to avoid CO poisoning is to follow safety guidelines. Place a CO detector in your home and have your gas appliances checked annually. With the right precautions, you can keep yourself and your family safe and healthy. Talk to your healthcare provider if you had exposure to carbon monoxide.

Medically Reviewed

Last reviewed on 07/20/2023.

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