A headache is the most common symptom of carbon monoxide (CO) poisoning. Other common symptoms include:
- feeling sick (nausea) and dizziness
- feeling tired and confused
- being sick (vomiting) and having abdominal (stomach) pain
- shortness of breath and difficultly breathing (dyspnoea)
The symptoms of CO poisoning can resemble those of food poisoning and the flu. However, unlike flu, CO poisoning does not cause a high temperature (fever).
You may notice that your symptoms are less severe at times when you are away from the source of the carbon monoxide.
The longer you breathe in CO gas, the worse your symptoms will get. You may lose your balance, vision and memory. Eventually, you may lose consciousness.
This can happen within two hours if there is a lot of CO in the air. However, the symptoms of CO poisoning can sometimes occur a number of days or months after breathing in carbon monoxide.
Symptoms of CO poisoning that develop later include:
- confusion
- memory loss
- co-ordination problems
High levels of carbon monoxide
If you have breathed in high levels of carbon monoxide, the symptoms can be much more severe and can include:
- intoxication (the effects of poisoning, such as an impaired mental state) and changes to personality
- vertigo (the feeling that you, or the environment around you, are spinning)
- ataxia (loss of physical co-ordination due to underlying damage to the nervous system and brain)
- breathlessness and tachycardia (a heart rate of more than 100 beats a minute)
- chest pain due to angina or heart attack
- seizures (an uncontrollable burst of electrical activity in the brain that causes muscle twitches, tongue biting and total body shaking)
- loss of consciousness (in cases where there are very high levels of carbon monoxide, death may occur within a few minutes)
At risk groups
Certain people in your household may be affected by CO poisoning more quickly than others. Those at particular risk include:
- people with heart or breathing problems
- babies and young children
- pregnant women
Pets may be the first to show signs of CO poisoning because they are very vulnerable to the effects of CO gas. The smaller an animal or a person is, the faster CO will affect them.
If your pet suddenly becomes ill or dies unexpectedly, and the death is not related to old age or an existing condition, you should investigate the possibility of a CO leak.
