Condition Basics

What is carbon monoxide poisoning?

Carbon monoxide poisoning happens when you breathe too much carbon monoxide. Carbon monoxide is a gas produced by burning any type of fuel—gas, oil, kerosene, wood, or charcoal. What makes this gas so dangerous is that when you breathe it, it replaces the oxygen in your blood. Without oxygen, cells throughout the body die, and the organs stop working.

You can't see, smell, or taste carbon monoxide. But if you breathe too much of it, it can become deadly within minutes. So be sure you know the signs of carbon monoxide poisoning, what to do if you have the symptoms, and how to keep it from happening.

What causes it?

Carbon monoxide can come from any source that burns fuel. Common sources are cars, fireplaces, powerboats, wood stoves, kerosene space heaters, charcoal grills, and gas appliances such as water heaters, ovens, and dryers. Usually they cause no problems. Trouble comes when:

• Cars, trucks, or other engines are left running in enclosed spaces, such as garages. Carbon monoxide can build up in a garage and leak back into the house. Even sitting in an idling car in an open garage can be dangerous. A motorboat or jet ski that is idling or working at a slow speed can be dangerous to a swimmer or someone being pulled.
• Fuel-burning appliances are not installed or used properly. Dangerous levels of carbon monoxide can build up inside houses and other buildings.
• Fuel-burning heating systems and appliances are used during cold weather, when doors and windows are closed. Chimneys in older buildings become blocked and release fumes into the homes or offices. Newer houses that are well insulated and tightly sealed can trap carbon monoxide inside.

What are the symptoms?

Early symptoms of carbon monoxide poisoning include:

• Headache.
• Dizziness.
• Nausea.

As carbon monoxide builds up in your blood, symptoms get worse and may include:

• Confusion and drowsiness.
• Fast breathing, fast heartbeat, or chest pain.
• Vision problems.
• Seizures.

If you have symptoms that you think could be caused by carbon monoxide poisoning, leave the area right away, and call 911 or go to the emergency room. If you keep breathing the fumes, you may pass out and die.

Carbon monoxide poisoning can occur suddenly or over a long period of time. Breathing low levels of carbon monoxide over a long period can cause severe heart problems and brain damage. See a doctor if:

• You often are short of breath and have mild nausea and headaches when you are indoors.
• You feel better when you leave the building and worse when you return.
• Other people you work or live with have the same symptoms you do.

How is it diagnosed?

It can be hard to know if you have carbon monoxide poisoning. The same symptoms can be caused by flu or other problems. In the winter months, doctors may suspect carbon monoxide poisoning in people who complain of severe headache, nausea, or dizziness. This is especially true if other household members or coworkers have the same symptoms. Even pets in the home may get sick.

If your doctor suspects carbon monoxide poisoning, he or she can order a blood test that measures the amount of carbon monoxide in your blood. You may have other blood tests to check your overall health and to look for problems caused by carbon monoxide.

How is carbon monoxide poisoning treated?

The best treatment is oxygen therapy. Breathing pure oxygen can bring the oxygen level in the blood back to normal. There are two kinds of oxygen therapy:

• 100% oxygen therapy. For this treatment, you breathe oxygen through a mask. This is the most common treatment.
• Hyperbaric oxygen therapy. For this treatment, you lie inside a chamber that delivers oxygen under high pressure. This quickly reduces carbon monoxide levels in the blood.

With quick treatment, most people recover within a few days. But long-term problems can show up later. Be sure to tell your doctor about any changes in vision, coordination, or behavior that occur in the weeks after treatment.

How can you prevent it?

Many people die every year from accidental carbon monoxide poisoning. There are some easy steps you can take to reduce your risk. One of the most important is to see a doctor right away if you think you have symptoms.

Safe use of vehicles

• Do not leave your car running in the garage, even if the garage door is open.
• Do not ride in the back of a pickup truck with a camper shell.
• Do not swim near a boat or jet ski that is idling.
• Do not swim near or be pulled behind a boat or jet ski that is operating at a slow speed.
• Do not sit in a running car or truck if the tailpipe is blocked with snow or mud.

Safe use of fuel-burning tools and appliances

• Have all fuel-burning appliances (such as oil or gas heaters, stoves, water heaters, and space heaters, fireplaces, and wood stoves) inspected each year.
• Check chimneys, flues, and vents regularly to make sure they are in good shape, properly connected, and not blocked.
• Never use a kerosene or propane heater in an enclosed area, such as a camper, motor home, trailer, or tent.
• Never use a gas or charcoal grill indoors.
• Never use a gas oven to heat your home.
• Do not close a fireplace or stove damper before the fire is completely out.
• Do not use gas-powered generators, lawn equipment, or engines in enclosed areas.

Carbon monoxide detectors

• Consider putting carbon monoxide detectors in your home near sleeping areas.
• If you install a detector, follow the directions closely. Know what to do if the alarm sounds.
• Understand that carbon monoxide detectors are a backup safety measure. They do not replace the need to check appliances regularly and use them safely.