Hematologist
CION Cancer Clinics
Transfusion reactions: what they feel like and when to act | CION Cancer Clinics
A transfusion reaction usually feels like a sudden chill, a fever or an itchy rash, and most are mild. Breathlessness, chest or back pain, swelling of the face, or dark urine are more serious: tell the nurse at once, or after going home, go to the nearest emergency department or call 108. This page explains the main reactions, what happens on the ward, and how future transfusions are made safer. At CION Cancer Clinics, our haematology team supports patients and families through treatment, cost questions and life at home.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- What does a transfusion reaction feel like?
- Which reactions are common, and which are serious?
- What happens if a reaction is suspected?
- Who is more likely to react, and how are reactions prevented?
- What do families often believe about transfusion reactions?
- What can this page not tell you?
- Common questions about transfusion reactions
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What to do now
During a transfusion, if you feel breathless, chest or back pain, swelling of the lips or face, a sudden chill or fever, or just feel something is wrong, press the call bell and tell the nurse straight away. After going home, if breathlessness, fever with shivering, very dark or red urine, or yellow eyes appear, go to the nearest emergency department or call 108. Say a transfusion was given recently.
The short answer
What does a transfusion reaction feel like?
Most reactions feel like a sudden chill, a rise in temperature, or an itchy rash with raised bumps, and most are mild. Rarely, a reaction causes breathlessness, a drop in blood pressure, back pain or dark urine, and these need urgent attention.
Why reactions happen
A transfusion puts cells and fluid from another person into your body. Your immune system may react to proteins in the donor plasma, to donor white cells, or, very rarely, to red cells of the wrong group. The volume itself can also strain the heart in some people.
When they tend to appear
Most reactions start during the transfusion or within a few hours of it, which is why the nurse checks your temperature, pulse and blood pressure regularly, and watches you closely at the start of each bag. Some reactions appear days later, after you are home, so it helps to know what to look for.
If a reaction is suspected, stopping the bag early is the right first step. It does not mean you can never have blood again.Not sure whether this applies to you?
Ask an oncologistThe main types
Which reactions are common, and which are serious?
Symptoms overlap, so only the team can say which reaction it is. These are the patterns they look for.
Fever and chills
A rise in temperature or shivering during or soon after the bag. Often caused by donor white cells. Usually mild, but it can be the first sign of something more serious, so it is always checked.
Allergic reactions
Itching and raised red bumps like hives are common and usually settle with treatment. Rarely, a severe allergy called anaphylaxis causes swelling of the face or throat, wheeze and a fall in blood pressure.
Breathing reactions
Breathlessness during or after a transfusion can mean fluid overload, called TACO, or a lung reaction called TRALI.
More likely if you have
- Heart or kidney problems
- Older age or small body size
- Several bags given quickly
Red cells being destroyed
Called a haemolytic reaction. The rare immediate type causes fever, back pain and red or dark urine. A delayed type appears days later, with yellow eyes and tiredness.
On the ward
What happens if a reaction is suspected?
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The bag is stopped
The nurse stops the transfusion, keeps the drip line open with a simple fluid, and calls the doctor.
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Checks at the bedside
Temperature, pulse, blood pressure and oxygen levels are measured. The nurse checks the bag label against your wristband and details again.
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Treatment for the symptoms
Depending on the reaction, you may be given medicine for itching or fever, oxygen, or treatment for a severe allergy.
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Samples to the blood bank
For anything beyond a mild reaction, blood and urine samples and the bag itself go back to the blood bank to be tested.
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A decision about the next transfusion
The haematologist decides whether the same bag can be restarted, a new one given, or future bags prepared differently.
Risk and prevention
Who is more likely to react, and how are reactions prevented?
People who need many transfusions, such as those with leukaemia, thalassaemia or bone marrow failure, meet more donors and so have more chances to react. Women who have been pregnant, and people with earlier reactions, are also more likely to have one.
Checks before every bag
Your blood group is tested and matched against the donor blood. Immediately before the bag goes up, two staff members check your name, date of birth and hospital number against the bag. Answer these questions fully each time, even if it feels repetitive. It is the most important safety step.
Adjusted blood for people who react
After repeated fever reactions, your team may request filtered (leucodepleted) blood. After allergic reactions, they may give a medicine beforehand or ask for washed cells. People at risk of fluid overload may receive bags more slowly, sometimes with a water tablet. These decisions are made by your haematologist.
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Commonly believed
What do families often believe about transfusion reactions?
"A shiver is just the cold drip, so no need to tell the nurse."
A chill can be the first sign of a reaction. Tell the nurse every time. It takes a minute to check and may prevent something more serious.
"After one reaction, blood can never be given again."
Most people who have had a mild reaction go on to have many more transfusions safely. The team may simply prepare the blood differently or give a medicine first.
"Blood from a relative will not cause a reaction."
Family blood can still cause reactions, and in some blood cancer patients it carries extra risks. It must be tested the same way and often needs irradiation. Ask the haematologist before arranging it.
"Once we are home, anything that happens is not related."
Delayed reactions can show up days later, with yellow eyes, dark urine or fever. Mention the recent transfusion to any doctor you see.
Being straight with you
What can this page not tell you?
It cannot tell you whether a symptom you had was a reaction, or which type. Fever, rash and breathlessness have many causes in someone on blood cancer treatment, including infection and the treatment itself. The team decides using the timing, the checks and the blood bank tests.
What to ask your team
Ask what kind of reaction it was, whether it has been recorded in your notes, and whether future blood needs to be prepared differently. Ask whether the blood bank tests found anything, and what signs to watch for over the next few days at home. If you are unsure whether a symptom is linked, it is always reasonable to call and ask. Ask for this to be written in your discharge summary, so any other hospital knows too.
What CION's team can do
CION's haematology team can review your transfusion history, explain what happened, and coordinate with the blood bank on how future bags should be prepared. For symptoms right now, the emergency department is the right place, not a phone call.
Questions we are asked
Common questions about transfusion reactions
How long after a transfusion can a reaction happen?
Most reactions start during the transfusion or within a few hours. Breathing reactions can appear within the first day. A delayed reaction, where red cells break down, can appear days to a couple of weeks later, with yellow eyes, dark urine or tiredness. Tell any doctor you see about the recent transfusion.
Is a fever during a transfusion always a reaction?
No. In someone with low white cells, a fever may be an infection that happened to start at the same time. That is why the team checks for both. A fever during low counts is treated seriously whatever the cause.
Can a transfusion give me an infection?
Donated blood in India is screened for HIV, hepatitis B, hepatitis C, syphilis and malaria. The chance of an infection is very small but not zero. Platelets, stored at room temperature, carry a slightly higher risk of bacteria, which can cause a high fever and shivering during the transfusion.
Can my child have a reaction too?
Yes, and young children may not be able to say what they feel. Watch for crying, restlessness, flushing, fast breathing or a rash, and tell the nurse straight away. Children on leukaemia treatment are watched closely during every bag.
What if the itching starts after we get home?
Mild itching without other symptoms can usually wait for a call to the ward or helpline. If there is also swelling of the lips, face or tongue, wheeze or breathlessness, go to the nearest emergency department or call 108 immediately.
Should I take a medicine before my next transfusion?
Only if your team prescribes it. Some people with repeated allergic or fever reactions are given a medicine beforehand, but this is not routine for everyone, and it can hide early warning signs. Do not take anything on your own before a transfusion.
Why do they ask my name and date of birth every time?
Because giving the wrong bag to the wrong person is the cause of the most serious reactions, and it is preventable. The repeated check is the safety net. Answer in full each time rather than just nodding, even if staff already know you well.
Will a reaction be recorded in my file?
It should be. Ask the team to note the type of reaction and any special blood requirements in your notes and discharge summary. Keep a copy or a photo on your phone and show it at any hospital where you may need blood.
Your Haematologist
Meet CION's haematologist. One specialist for your blood report and your plan.
Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- NHS — Blood transfusion
- NHLBI — Blood Transfusion
- NICE — Blood transfusion (NG24)
- WHO — Blood safety and availability
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Irradiated and leucodepleted blood productsSpecial blood that lowers some reactionsPlatelet refractoriness: when transfusions stop workingWhen platelet counts do not riseIron chelation for transfusion overloadThe long-term effect of many transfusionsSupportive care in haematologyAll the supportive care guides in one place
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Had a reaction and unsure what comes next?
For symptoms now, go to the nearest emergency department or call 108. To understand what happened, tell us what has been found so far and we will help you reach the right specialist.