Carbon monoxide poisoning is an illness caused by exposure to too much carbon monoxide — a colorless, odorless and tasteless gas. Too much carbon monoxide in the air you breathe can greatly diminish your ability to absorb oxygen, leading to serious tissue damage. Carbon monoxide poisoning can lead to death.

Carbon monoxide is produced by appliances and other devices that generate combustion fumes, such as those that burn gas or other petroleum products, wood and other fuels. The danger occurs when too much carbon monoxide accumulates in a contained, poorly ventilated space.

Although the signs of carbon monoxide poisoning can be subtle, the condition is a life-threatening medical emergency. Get immediate care for anyone who may have carbon monoxide poisoning.

Signs and symptoms of carbon monoxide poisoning may include:

  • Dull headache
  • Weakness
  • Dizziness
  • Nausea
  • Vomiting
  • Shortness of breath
  • Confusion
  • Blurred vision
  • Loss of consciousness

Carbon monoxide poisoning can be especially dangerous for people who are sleeping or intoxicated. The fumes may be fatal before anyone realizes there's a problem.

When to see a doctor

If you suspect you've been exposed to carbon monoxide, get into fresh air immediately and seek emergency medical care. If possible, open windows and doors on the way out of the house.

Carbon monoxide poisoning is caused by inhaling combustion fumes. When there's too much carbon monoxide in the air, your body replaces the oxygen in the hemoglobin of your red blood cells with carbon monoxide. This keeps life-sustaining oxygen from reaching your tissues and organs.

Various appliances fueled by wood or gas produce carbon monoxide, including:

  • Fuel-burning space heaters
  • Furnaces
  • Charcoal grills
  • Cooking ranges
  • Water heaters
  • Fireplaces
  • Portable generators
  • Wood-burning stoves
  • Car and truck engines

Normally the amount of carbon monoxide produced by these sources isn't cause for concern. But if appliances aren't kept in good working order or if they're used in a closed or partially closed space — such as using a charcoal grill indoors or running your car in a closed garage — the carbon monoxide can build to dangerous levels.

Smoke inhalation during a fire also can cause carbon monoxide poisoning.

Exposure to carbon monoxide may be particularly dangerous for:

  • Unborn babies. Fetal blood cells take up carbon monoxide more readily than adult blood cells do. This makes unborn babies more susceptible to harm from carbon monoxide poisoning.
  • Children. Young children take breaths more frequently than adults, which may make them more susceptible to carbon monoxide poisoning.
  • Older adults. Elderly people who experience carbon monoxide poisoning may be more likely to develop brain damage.

Depending on the degree and length of exposure, carbon monoxide poisoning can cause:

  • Permanent brain damage
  • Damage to your heart, possibly leading to life-threatening cardiac complications years after the poisoning
  • Death

If you or someone you're with develops signs or symptoms of carbon monoxide poisoning — headache, dizziness, nausea, vomiting, chest pain, confusion — get into fresh air immediately and call 911 or emergency medical help.

Hospital staff will need critical information as soon as you arrive. On the way to the hospital, try to prepare to answer questions about:

  • Possible sources of carbon monoxide exposure
  • Signs or symptoms, and when they started
  • Any mental impairment, including confusion and memory problems
  • Any loss of consciousness
  • Other medical conditions with which the affected person has been diagnosed, including pregnancy
  • Smoking habits

If you're brought to an emergency room with suspected carbon monoxide poisoning, you may begin treatment immediately. To confirm your diagnosis, the doctor may have a blood sample taken to test for carbon monoxide in your blood.

If you or someone you're with develops signs or symptoms of carbon monoxide poisoning — headache, dizziness, nausea, vomiting, chest pain, confusion — get into fresh air immediately and call 911 or emergency medical help.

Once you're at the hospital, treatment may involve:

  • Breathing pure oxygen. In the emergency room, you may breathe pure oxygen through a mask placed over your nose and mouth. This helps oxygen reach your organs and tissues. If you can't breathe on your own, a machine (ventilator) may do the breathing for you.
  • Spending time in a pressurized oxygen chamber. In some cases, hyperbaric oxygen therapy is recommended. With this therapy, you're placed in a full-body pressurized chamber. Inside the chamber, air pressure is more than twice as high as normal atmospheric pressure. This speeds the replacement of carbon monoxide with oxygen in your blood. Hyperbaric oxygen therapy may be used in cases of severe carbon monoxide poisoning. It may also be recommended for pregnant women because unborn babies are more susceptible to damage from carbon monoxide poisoning.

Simple precautions can help prevent carbon monoxide poisoning. Consider the following:

  • Invest in carbon monoxide detectors. Install a carbon monoxide detector in the hallway near each sleeping area in your house. Check the batteries every time you check your smoke detector batteries — at least twice a year. If the alarm sounds, leave the house and call the fire department or local utility company from a nearby phone. Carbon monoxide detectors are also available for motor homes and boats.
  • Open the garage door before starting your car. Never run your car in a closed garage. If you have an attached garage, keep the garage door open and the door to the house firmly closed while the car is running.
  • Use gas appliances as recommended. Never use a gas stove or oven to heat your home. Use portable gas camp stoves only outdoors. Use fuel-burning space heaters only when someone is awake to monitor them and doors or windows are open to provide fresh air. Don't run a generator in an enclosed space, such as the basement or garage.
  • Keep your gas appliances and fireplace in good repair. Make sure your gas appliances are properly vented. Clean your fireplace chimney and flue every year. Ask your utility company about yearly checkups for all gas appliances, including your furnace.

If carbon monoxide poisoning has occurred in your home, it's critical to find and repair the source of the carbon monoxide before you return. Your local fire department or utility company may be able to help.

Feb. 21, 2012