Carbon monoxide (CO) is a colorless, odorless gas produced by stoves, heating systems and gasoline engines. Knowing the warning signs of CO poisoning can save your life. CO poisoning feels much like the flu without the fever. Symptoms may include dizziness, nausea, fatigue, headache and irregular breathing. If CO poisoning is the cause, symptoms will disappear when you go outside and return when you re-enter the house. If you suspect a leak, evacuate your home immediately and call the nearest poison control center. Get your heating system and fuel-burning appliances checked yearly to ensure proper function.