What are platelets?

Platelets are tiny cells in your blood which help form clots to help stop bleeding. They develop from stem cells in your bone marrow (the spongy material inside your bones). They are then released from your bone marrow into your blood, and travel around the body in your bloodstream.

Platelets usually survive for 7 to 10 days, before being destroyed naturally in your body or being used to clot the blood.

A low platelet count can increase your risk of bleeding.

What is a platelet transfusion?

A platelet transfusion is when you are given platelets from carefully screened donors. Sometimes this is called a platelet infusion. You will be given platelets by a drip into one of your veins. This increases the number of platelets in your blood.

Why do I need a platelet transfusion?

Your doctor may recommend a platelet transfusion if your platelet count is low. Your may have a low platelet count if your bone marrow is not working normally. This may be because you have cancer, leukaemia or a blood disorder.

Treatment with chemotherapy, targeted therapies and sometimes surgery can also affect your platelet count. A type of radiotherapy called total body irradiation (TBI) can also affect your bone marrow and platelet count.

During your cancer treatment, your doctor will closely monitor your platelet count. You will have regular blood tests to check the numbers of blood cells in your blood, including your platelets. This test is called a full blood count (FBC).

The normal platelet count in an adult is between 150 and 400 x 109 per litre. But it is normal for the platelet count to be lower than this when you are having cancer treatment. The risk of bleeding increases when the platelet count is below this level. But there is usually only a risk of bleeding if the platelets are as low as 10 or 20 x 109 per litre.

Signs of a low platelet count include:

  • nosebleeds
  • heavy periods
  • bruising
  • tiny blood spots under the skin (petechiae)
  • bleeding gums.

Tell your doctor straight away if you notice any of these symptoms.

Serious bleeding is rare and usually only happens if the platelet count is very low (below 10) or if it is below 30 and you also have a high temperature. Your body uses up platelets faster if you have a high temperature. If you are at home with a high temperature and think that your platelet count could be low, contact the hospital on the emergency numbers you have been given.

You may also have a platelet transfusion if your platelet count is low before a procedure where there is a risk of bleeding. This includes surgery, a lumbar puncture or bone marrow aspiration. The platelet transfusion will reduce the risk of any bleeding during or after the procedure.

Decisions about treatment

Before you have a transfusion, your doctor will explain why it is being given. They may also give you information to read. You will be asked to give your permission (consent) for the hospital staff to give you a platelet transfusion. Medical treatment can only be given with your consent.

You may decide not to have a platelet transfusion. It is important to tell your doctor or nurse if you decide not to have treatment. They will record your decision in your medical notes.

You do not have to give a reason, but it can be helpful to tell the staff your concerns, so they can give you the best advice.

Jehovah’s Witnesses may choose not to have some types of blood products. If this affects you, talk to your doctor about other treatments or ways to manage a low platelet count.

Having a platelet transfusion

Platelets come from people who donate their blood. In most cases, platelets do not need to be matched to your blood group in the same way as a blood transfusion.

The platelets for transfusion are yellow-coloured and stored in small plastic bags. Platelets are given by a drip (infusion) into one of your veins. A nurse will put a short, thin tube (cannula) into a vein in your arm or hand. This is then connected to a drip. If you have a central line or PICC line, your nurse can connect this to your drip instead.

Platelet infusion duration

The transfusion usually takes 15 to 30 minutes. You may have it in an outpatient clinic, in a day unit, or as an inpatient. The transfusion increases the number of platelets in your blood straight away. But sometimes the benefits do not last long, and you may need more transfusions.

Possible side effects of platelet transfusions

Reactions to the platelets

During the transfusion, your nurse will regularly check your temperature, pulse and blood pressure. This is to make sure you are not having a reaction to the platelets.

Some people may have:

  • shivering
  • a rise in temperature
  • itching
  • a skin rash.

The nurses will check you for any reactions. They will stop the transfusion and quickly treat any symptoms. Tell your nurse straight away if you feel unwell during your transfusion.

Contact the hospital if you have any problems after you get home.

Becoming resistant (refractory) to platelets

Rarely, if you have had lots of platelet transfusions, your platelet count may not improve after a transfusion. This is called becoming refractory or resistant to platelets. If this happens, you will have tests to find the cause. You may be given platelets that are better matched to your own.

Are platelet transfusions safe?

Some people worry that the platelets they are given may be infected by disease. People who donate blood or platelets are carefully screened for infections or viruses such as hepatitis or HIV. This is to make sure the donations are as safe as possible. All donated platelets are tested in the laboratory for infection. Very rarely, there may be an infection in the platelets that is not found by these tests. But the risk of being given infected platelets is very small.

If you have any concerns about receiving a platelet transfusion, talk to your doctor or specialist nurse.

Irradiated blood products

Some people may need to have blood products that have been treated with irradiation.

You may need irradiated blood products if you have had:

Your doctor will tell you if this applies to you.

Irradiated blood products lower the risk of the donated cells reacting against your own. The radiation will not damage the blood product or make you radioactive. Your doctor will record in your medical notes if you should only have irradiated blood products.

They will also give you a special card to carry, in case you are treated at another hospital. Keep this card with you at all times and remind your hospital team that you need irradiated blood or platelets.

About our information


  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.