A blood transfusion is when blood is taken from one person (a 'donor') and given to someone else. Donors give some of their blood in advance, and it is stored until it is needed.
To give you a blood transfusion, your healthcare team will put a drip (a short plastic tube attached to a bag of blood) into a vein in your arm, and the blood will slowly enter your body. It may take up to 4 hours, but some transfusions can happen faster. There are some risks with having a transfusion (such as allergic reactions), but overall they are safe to have.
There are different types of blood transfusion, and each one replaces different parts ('components') of your blood. The type used depends on the reason you need a blood transfusion.
Cells that carry oxygen round your body. Red blood cell transfusions can help with anaemia.
Cells that work with 'clotting factors' in the plasma to make your blood clot (to stop a cut or wound from bleeding). Platelet transfusions can help with clotting problems.
The liquid part of your blood. It is normally frozen to preserve the clotting factors in it, and you may hear it called 'fresh frozen plasma' or 'FFP'. Plasma transfusions can help with clotting problems.
A blood component made from plasma that contains lots of clotting factors. Cryoprecipitate transfusions can help with clotting problems.
A blood product made from plasma. It contains specific clotting factors that help people who are taking medicines that make it difficult for their blood to clot.