Carbon monoxide

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Date: November 2024, Version 3

Quick take

If you think you have been exposed to carbon monoxide, please seek urgent medical attention.

What is it?

Carbon monoxide (CO) is a colourless gas with no smell or taste. It is produced when fuel like gas, coal, coke, barbecue charcoal, or wood does not burn fully. This is most often due to a boiler being faulty but can also be because of faulty or wrongly fitted gas fires and wood burners, or barbecues being used in enclosed spaces. 

Why is carbon monoxide dangerous?

When carbon monoxide is breathed in, it reduces the amount of oxygen in your bloodstream. Breathing in high levels of carbon monoxide can lead to you falling unconscious and suffocating. 

What are the symptoms of carbon monoxide poisoning?

If you are exposed to high levels of carbon monoxide you might have a headache, notice you have skin reddening/flushing, feel sick, tired, dizzy or weak, have problems with balance and memory, or feel like you have flu.

Poisoning from high levels of carbon monoxide causes breathlessness, chest pain, seizures, and/or loss of consciousness.

Can carbon monoxide exposure in pregnancy affect the baby?

Yes. Exposure to high levels of carbon monoxide in pregnancy can reduce the amount of oxygen reaching your baby in the womb, potentially affecting its growth and development. Carbon monoxide poisoning can lead to suffocation and death of the mother and baby. 

How can I avoid exposure to carbon monoxide?

To avoid exposure to high levels of carbon monoxide you should make sure that all household gas and solid fuel appliances are installed and regularly serviced by a qualified professional. 

In addition, chimneys in houses where solid fuel is burned should be swept regularly, household carbon monoxide alarms should be used, and barbecues and fuel heaters should not be lit in confined/unventilated spaces (including tents or indoors). 

Warning signs of a problem include a gas fire burning with a yellow flame instead of blue, sooty marks on the covers of gas fires or yellow/brown stains around boilers, stoves or fires. If the appliance is not burning properly then carbon monoxide levels may be increased. In such cases, the appliance should be switched off immediately and investigated by a qualified professional.

What should I do if I think I have been exposed to carbon monoxide during pregnancy?

You should call 999 if you have symptoms of carbon monoxide poisoning.

If you think you may have been exposed to a high level of carbon monoxide but are conscious and breathing normally, go to A&E.

Will I or my baby need extra monitoring?

If you have been exposed to high levels of carbon monoxide during pregnancy, your carbon monoxide and blood oxygen levels will be checked and you will be offered extra monitoring of the baby’s growth and wellbeing.

Are there any risks to my baby if the father has been exposed to carbon monoxide? 
There is currently no evidence that carbon monoxide exposure in the father can harm your baby through effects on the sperm.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet, please discuss them with your health care provider. They can access more detailed medical and scientific information from www.uktis.org.

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.

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