Hematologist
CION Cancer Clinics
Does a transplant change your blood group? | CION Cancer Clinics
Yes, a stem cell or bone marrow transplant from a donor slowly changes your blood group to the donor's, because the new marrow makes all your new blood. A transplant using your own cells does not change it, and neither does a kidney, liver or heart transplant. Your genes, your features and what you pass to your children stay your own. 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
- Can a transplant really change my blood group?
- Which transplants change the blood group and which do not?
- How does the change happen after a donor transplant?
- What do families get wrong about blood group and transplant?
- What do the words on a transplant report mean?
- What does a new blood group mean for everyday life?
- What changes after a donor transplant, and what stays yours?
- Common questions about transplant and blood group
The short answer
Can a transplant really change my blood group?
Yes, but only one kind of transplant does it. After a stem cell or bone marrow transplant from another person, your blood group slowly becomes the donor's blood group. A kidney or liver transplant does not change it.
Why this happens
Your blood group is written on the surface of your red cells. Those cells are made in the bone marrow, the soft tissue inside your bones. A donor stem cell transplant replaces the cells that make blood with the donor's cells. Once the new marrow is working, every new red cell it makes carries the donor's group. Your old red cells wear out and are not replaced.
Why the doctors did not insist on a matching group
Families are often surprised that a brother with group B can donate to a sister with group O. For a stem cell transplant, the match that matters is the tissue type, called HLA. The blood group matters far less. A mismatch in blood group needs extra care in the first months, but it is not a reason to turn down a well-matched donor.
The change affects your blood. The rest of your body, your skin, hair and organs, keeps your own make-up.Not every transplant
Which transplants change the blood group and which do not?
The word transplant covers very different treatments. Only one of them replaces the factory that makes your blood.
Stem cell transplant from a donor
Called allogeneic, meaning the cells come from someone else. This is the one that can change your group, if the donor's group is different from yours.
Often used for
- Some acute leukaemias
- Thalassaemia major
- Severe marrow failure
Transplant with your own cells
Called autologous. Your own stem cells are collected, stored and given back after strong treatment. Your blood group stays exactly as it was.
Kidney, liver or heart transplant
An organ transplant does not replace your bone marrow, so your blood group does not change. Here the blood group of the donor usually does need to suit yours.
A blood transfusion
Transfused red cells live for a limited time and are not replaced by your marrow. A lab test done soon after may look confusing, but your group itself does not change.
Not sure whether this applies to you?
Ask an oncologistStep by step
How does the change happen after a donor transplant?
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Before the transplant
The transplant centre tests both your blood group and the donor's. If they differ, the team plans in advance which blood group of red cells, platelets and plasma you will receive in the months ahead.
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The new marrow settles in
The donor cells travel to your bones and start making blood. Doctors call this engraftment. For a while, your blood holds a mix of your old red cells and new ones made by the donor marrow.
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The mixed phase
Your lab report may show an unclear or mixed group. This is expected. Some patients need transfusions during this time, and the blood bank follows the plan set by the transplant team, not your old card.
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The donor group takes over
Over several months your blood tests show the donor's group. How long this takes varies from person to person, and your team decides when the change is complete.
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A new record
You are given a letter or card that states your new group and your transplant history. Keep it with your reports for life.
Commonly believed
What do families get wrong about blood group and transplant?
"The donor must have the same blood group, or the transplant will fail."
For a stem cell transplant, the tissue match decides the choice of donor. A different blood group needs careful planning, but many transplants are done safely across blood groups. Do not rule out a sibling just because their group is different.
"After the transplant, my whole body becomes the donor's."
Only the blood and the immune cells change. Your skin, hair, organs and the genes you pass to your children stay your own. A cheek swab would still show your own genetic make-up.
"My old blood group card is still correct."
It is not, once the change has happened. Using an old card in an emergency could lead to the wrong blood being chosen. Tell every hospital and lab that you have had a donor transplant.
"My kidney transplant must have changed my group too."
No. An organ does not make blood. Your group stays the same after a kidney, liver or heart transplant.
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On your report
What do the words on a transplant report mean?
- ABO mismatch or ABO incompatible
- The donor and the patient have different blood groups. It is noted so the blood bank can plan transfusions.
- HLA match
- How closely the donor's tissue type matches yours. This decides the choice of donor far more than blood group does.
- Engraftment
- The point at which the donor's cells have settled and started making blood cells.
- Chimerism
- A test showing how much of your blood comes from the donor. Full donor chimerism means almost all of it does.
- Rh type
- The positive or negative part of your group. It can change to the donor's type too.
Living with it
What does a new blood group mean for everyday life?
For most people it changes very little day to day. What it changes is paperwork and safety. Every future transfusion, surgery or emergency admission needs the right group on record.
Tell every doctor and lab
Carry your transplant summary and the letter stating your group. Before any blood test or procedure, say that you have had a donor stem cell transplant. Labs repeat the group test before a transfusion, and your history helps them read an unexpected result.
Donating blood and pregnancy
People who have had a stem cell transplant are not accepted as blood donors. If you plan a pregnancy later, tell the pregnancy care team your history, because the routine blood group tests can look unusual.
What this page cannot tell you
It cannot tell you when your own group will change, or whether it has. Only your blood tests and your transplant team can say that. It also cannot tell you whether a transplant is right for you.
CION's haematology team reviews your case with a tumour board and coordinates care with qualified transplant centres. Ask them which centre, and what the blood group plan will be.Side by side
What changes after a donor transplant, and what stays yours?
Changes to the donor's
Stays your own
Blood group and Rh type, over several months
The genes in your skin, hair and organs
The DNA found in a blood sample
The DNA found in a cheek swab
Your immune system, which needs your childhood vaccines again
What you pass on to your children
The blood group your transfusions are matched to
Your face, height, features and personality
Questions we are asked
Common questions about transplant and blood group
My brother's blood group is different from mine. Can he still be my donor?
Often yes. For a stem cell transplant the tissue type, called HLA, is what decides whether a brother or sister is a good match. A different blood group adds planning around transfusions in the early months. Your transplant team will look at the full picture and explain why a donor is or is not suitable.
Will my blood group definitely change after the transplant?
Only if the donor's group is different from yours and the donor cells settle fully. If the groups are the same, nothing changes. If the transplant uses your own stem cells, nothing changes either. Your team confirms the change with repeat blood tests, not by assumption.
How long does the change take?
It happens gradually over several months, as your old red cells wear out and the donor marrow replaces them. The exact time differs between people and depends on the groups involved. Some people need transfusions in the meantime. Your transplant team will tell you when your record can be updated.
Does a kidney or liver transplant change the blood group?
No. Blood is made in the bone marrow, and an organ transplant does not replace the marrow. Your group stays as it was. In organ transplants the donor's group usually has to suit yours, which is the opposite of what many people expect after reading about stem cell transplants.
Will my children inherit the donor's blood group?
No. Eggs and sperm are not made by the bone marrow, so the genes you pass to your children are your own. Your child's blood group comes from your original genes and the other parent's. This is one of the most common worries, and it is simply not how inheritance works.
What should I do with my old blood group card?
Once your team confirms the new group, keep the old card only as history and carry the new letter. Update your records with your regular doctor, and tell any hospital about your transplant before a procedure. In an emergency, the lab will test your group again before giving blood.
Can I donate blood after a stem cell transplant?
No. People who have had a stem cell or bone marrow transplant are not accepted as blood donors. This protects both you and the person who would receive the blood. You can still support a blood drive by encouraging healthy family members and friends to donate.
Does CION do stem cell transplants?
CION's haematology team assesses your case, presents it to a tumour board and coordinates your care with qualified transplant centres. Ask the team which centre is being suggested, how the donor will be tested, and how blood group differences will be handled. Bring every report you have to the first visit.
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 — Stem cell and bone marrow transplants
- National Cancer Institute — Stem Cell Transplants in Cancer Treatment
- Cancer Research UK — Stem cell and bone marrow transplants
- Leukemia & Lymphoma Society — Stem cell transplantation
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
Is Leukaemia Always Fatal?What shapes the outlook when a transplant is being discussedIs a Bone Marrow Test Dangerous or Paralysing?The test that comes before most transplant decisionsLeukaemia guideThe conditions where a donor transplant is most often consideredHaematology MythsOther beliefs about blood conditions, checked
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