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Blood transfusion

A blood transfusion is when you're given blood from someone else (a donor). It's a very safe procedure that can be life-saving.

Why a blood transfusion is done

Common reasons for needing a blood transfusion are:

  • anaemia (lack of red blood cells)
  • conditions affecting red blood cells, such as sickle cell disease or thalassaemia
  • types of cancer or cancer treatment that affect blood cells, such as chemotherapy or stem cell transplants
  • severe bleeding, usually from surgery, childbirth or a serious accident

A blood transfusion can replace blood you've lost. It may just replace the liquid or cells found in blood (such as red blood cells, plasma or cells called platelets).

Ask your doctor or nurse why they think you need a transfusion if you're not sure.

What happens at a blood transfusion

Before you have a blood transfusion, the procedure will be explained to you. You will need to sign a consent form.

A sample of your blood will be taken to check your blood group.

You'll only receive blood that's safe for someone with your blood group.

During a blood transfusion:

  • you sit or lie down in a chair or bed
  • a needle goes into a vein in your arm or hand
  • the needle connects to a tube and a bag of blood
  • blood runs through the tube into your vein

It can take up to 4 hours to receive 1 bag of blood, but it's usually faster than this.

You can normally go home soon after, unless you are seriously unwell or received a lot of blood.

During and after a blood transfusion

You might feel a sharp prick when the needle is first inserted into your vein. You shouldn't feel anything during the transfusion.

You'll be checked regularly while you receive blood. Tell a member of staff if you feel unwell or uncomfortable.

Some people develop a temperature, chills or a rash. This is usually treated with paracetamol or by slowing down the transfusion.

Your arm or hand may ache and have a bruise for a few days after.

Contact your GP if you feel unwell within 24 hours of having a blood transfusion. This is especially important if you have trouble breathing or pain in your chest or back.

Risks of blood transfusions

Blood transfusions are common and safe procedures.

All donor blood is checked first. This is to make sure it doesn't contain serious infections such as hepatitis or HIV.

There is a very small risk of complications. This can include an allergic reaction to the donor blood or a problem with your heart, lungs or immune system.

Risks will normally be explained before you have a transfusion. In cases of emergency, this will not always be possible. Speak to your doctor or nurse if you have any concerns.

Alternatives to a blood transfusion

A blood transfusion will only be recommended if it's needed and when other treatments will not help.

If you need a transfusion, have anaemia or are due to have surgery, you may be given medicine to:

  • lower your risk of bleeding
  • boost your number of red blood cells

These medicines can lower your chances of needing a blood transfusion.

Giving blood afterwards

You cannot give blood if you've had a blood transfusion.

This is a safety measure. It helps lower the risk of a serious condition called variant CJD (vCJD) being passed on by donors.

Find out more about who can give blood on the Irish Blood Transfusion website.

Content supplied by the NHS and adapted for Ireland by the HSE.

page last reviewed: 22/12/2020
next review due: 22/12/2023

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This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.