You can find out your blood group by giving blood.
To find out someone's blood group, a sample of their blood has to be taken and tested. However, GPs do not routinely check people's blood groups.
When is someone's blood group checked?
Healthcare professionals sometimes need to know a person's blood group for medical reasons.
If you need a blood transfusion, the blood group you receive must be compatible with your own blood group. Your blood type will therefore be tested before you receive a blood transfusion to make sure the two are compatible. Giving someone blood from the wrong group can potentially be life-threatening.
If you're pregnant, your blood will be tested to see if it's rhesus negative or positive. Read more information about rhesus disease.
Healthcare professionals will also check a person's blood group before they:
- give blood
- have an operation (surgery)
- donate an organ for transplant
Give blood and find out your blood group
Your blood group will be checked if you donate blood through the National Blood Service, so it can be matched to someone with the same blood group or one that is compatible.
Some blood groups cannot be mixed with each other because chemicals in the blood (antigens) can attack one another, causing the blood to clot.
Your blood will be tested before you give blood, and your blood group will be recorded on your official donor card.
Read the answers to more questions about NHS services and treatments.
Further information:
Your health, your choices