About side effects

Your transplant team will monitor you closely for side effects and complications during and after your treatment. Side effects are often caused by the conditioning treatment you have to get your body ready for the transplant.

The side effects will depend on the type of conditioning treatment you had. People having a reduced-intensity transplant may have less severe side effects. Your transplant team will tell you more about what to expect.

Most side effects are worse when your blood count is lowest. This is usually during the first 2 weeks after the transplant while you are still in hospital. When your blood count goes up, the side effects will start to improve.

When you go home after the transplant, you may still have side effects. You will be given drugs to prevent or reduce side effects. You will see your specialist doctor or nurse regularly. If you are worried about anything, contact them on the 24-hour hospital phone number you have been given. Always let them know about the side effects you have. There are often ways they can be controlled or helped.

Treatment may also cause side effects that develop months or years after treatment. These are called late effects.

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is called neutropenia.

You will be given drugs to prevent and treat infections. Your nurses and doctors will take your temperature regularly and check for signs of infection. They will also ask you to tell them if you have symptoms that could be a sign of infection. These include:

  • feeling cold and shivery
  • a sore throat
  • a cough or runny nose
  • pain when passing urine (peeing)
  • diarrhoea.

The hospital staff try to protect you from possible infections. But most people will need antibiotics at some point while their immune system is recovering.

We have more information about avoiding infection.


You may be restricted to only a few visitors each day. The ward nurses will tell your visitors how to help protect you from infections. People should not visit you if they feel unwell or have an infection.


This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. This is called anaemia. It can make you feel tired and short of breath. You may need blood transfusions until your body starts to make enough red blood cells again.

Irradiated blood

For several months after your transplant, any blood or platelet transfusions you are given are first treated with radiation (irradiated). This is to prevent problems caused by white blood cells called lymphocytes, which are in the donated blood. Irradiated blood is not radioactive and will not harm you or anyone you come into contact with.

Some people may need any blood or platelet transfusions to be irradiated for the rest of their lives. Your doctor will talk to you about this. You will be given a medical alert card to carry in case you need blood in an emergency.

Bruising and bleeding

This treatment reduces the number of platelets in your blood. You are likely to need platelets as a drip (infusion) to reduce the risk of bleeding or bruising. Any platelets you have will be treated with radiation (irradiated).

Your doctors and nurses will examine you regularly for bruises or little red spots on the skin. Tell a doctor or nurse straight away if you have:

  • any bruising you cannot explain
  • a nosebleed
  • bleeding gums
  • blood in your stools (poo) or urine (pee).

Tiredness (fatigue)

You will probably feel extremely tired and spend a lot of time sleeping. Sometimes you may feel too tired to concentrate on reading or watching television.

At times, you may not feel able to have visitors, or see them for too long. Let them know how you are feeling so they do not disturb you if you want to rest.

We have more information about managing fatigue.


Even though you are tired, it is a good idea to try to do some gentle exercise, such as stretching. A physiotherapist will show you how. This helps reduce the chances of getting a blood clot, and it keeps your muscles working and toned.

Some transplant units may have an exercise bike that you can use when you are feeling better and your blood counts have improved.

Feeling sick

The nurses will give you anti-sickness drugs (anti-emetics) regularly. If you still feel sick, tell your nurse or doctor. They can change the anti-sickness drug to one that works better for you.

We have more information about feeling sick.

Sore mouth

The treatment can cause a sore mouth and throat. You may also get painful mouth ulcers. This can make you more likely to get a mouth infection. Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals. If your mouth is sore:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco and foods that irritate your mouth.

We have more information about sore or dry mouth and ulcers.

Eating problems

During treatment, it is important you don’t lose too much weight. Try to eat small meals and snacks regularly, even if you do not have much appetite or if food tastes different. Your nurses and dietitian will give you advice.

If you have a sore mouth, eating may be difficult. You may need to have nutritional drinks until you can eat properly again. Sometimes people need to have liquid food through a thin, soft tube that goes down the nose into the stomach (a feeding tube).

Some people may have another type of liquid food that is given through their central line or PICC line. As you start to eat again, the amount of liquid food you are given is gradually reduced.

Hair loss

This is a common side effect of chemotherapy. You usually lose all the hair on your head. Your eyelashes, eyebrows and other body hair may also thin or fall out. It is almost always temporary and your hair will grow back after chemotherapy ends. Your nurse can give you advice about coping with hair loss.

We have more information about hair loss.


This can sometimes be severe. You will be given drugs to control diarrhoea. The nurses will take samples to check for an infection, and you will be given antibiotics if you need them.

Try to drink at least 2 litres (3½ pints) of fluids every day. Some people may need to have fluids through a drip until the diarrhoea improves. Let the nurses know if it does not get better, or if the skin around your bottom gets sore.

Bladder irritation

Some chemotherapy drugs may irritate your bladder and cause discomfort when you pass urine. You may be given fluids through a drip (infusion) and some drugs to help prevent bladder irritation. Drink at least 2 litres (3½ pints) of fluids each day. It is also important to empty your bladder regularly and try to pass urine (pee) as soon as you feel the need to go.

Tell your doctor or nurse straight away if you feel any discomfort or stinging, or if you notice any blood when you are peeing.

Effects on the lungs

Treatment can sometimes cause changes to the lungs. This is more likely if you already have lung problems. Always tell your doctor if you notice wheezing, a cough, or feel breathless. You should also tell them if any of these problems get worse.

Graft-versus-host disease (GVHD)

The donor's stem cells (the graft) may sometimes react against your own cells (the host). This is called graft-versus-host disease (GVHD).

Less common side effects of donor stem cell transplants

There are some other less common problems that may happen after the transplant. Your doctors and nurses will monitor you closely for any of these complications.

Virus infections

Because your immune system is not working well, you are more at risk from infections caused by different viruses. Some viral infections you had before may become active again. Your doctors will check for certain viruses that may cause more serious problems.


Most people will have had CMV by the time they are an adult. It rarely causes symptoms, so you will not usually know you have had it. It stays in your body and your immune system keeps it under control. This means it is not active and does not cause problems. But if your immune system is weakened, the CMV virus may become active again and cause problems.

Before your transplant, you and your donor are checked for CMV. If you are CMV negative, doctors try to match you with a donor who is the same.

After your transplant, even if you have not had CMV, you have regular blood tests to check for it. People who have not had CMV may catch it after a transplant.

Epstein-Barr virus

Most people have EBV at some time during their lives, but it can become active again after a transplant. If EBV infection gets out of control, there is a very low risk it may lead to developing another cancer after a transplant. Because of this, you have regular blood tests to check for EBV and treatment if needed. Your doctor will tell you more about this.


All blood in the UK is screened for hepatitis B and C. People having a donor stem cell transplant now have blood or platelet transfusions checked for hepatitis E virus (HEV).

HEV is not easily passed from person to person, but it can be passed on through a blood transfusion. It can also be present in pork products, shellfish and other meat. Look at our advice on eating and drinking after you go home.

HEV is usually a very mild infection that goes away by itself. But if your immune system is weak, it may not be able to get rid of it. So over time it may lead to liver problems.

Mixed chimerism

Chimerism is a word doctors use to describe how well your donor’s cells have engrafted. After transplant, the aim is for total chimerism (100%). This is when all your blood and bone marrow are from your donor.

Mixed chimerism means some of your own cells are still there. This is more likely if you had reduced-intensity conditioning. Because you had lower doses of chemotherapy, some of your own blood cells survive.

Sometimes mixed chimerism gradually improves on its own. If it does not get better, doctors can treat it by giving you white blood cells (lymphocytes) from your donor. This is called a donor lymphocyte infusion (DLI). The donor white cells destroy any of your remaining cells. The aim is to increase the chimerism level to 100%.

The lymphocytes are given to you by a drip into your line. If these cells were not saved when your donor had their first collection, they can donate more cells. They will not need injections of growth factors for this. The lymphocytes are collected in the same way as the stem cells were.

The main risk of a DLI is that you might develop a condition called GVHD.

Graft failure

Sometimes the donor stem cells do not grow and make enough new blood cells. This is known as graft failure.

If there are not enough new, healthy blood cells, side effects such as infections, bruising, bleeding and anaemia can cause serious problems.

Total graft failure is very serious but rare. The only way to treat it is by having another infusion (drip) of stem cells from the donor after some conditioning drugs.

Veno-occlusive disease

In some people, blood vessels in the liver may become swollen and blocked soon after transplant. This is known as veno-occlusive disease or sinusoidal obstruction syndrome (SOS). It can cause pain or swelling in your tummy or right side, or jaundice (yellowing of the skin or eyes). Some people notice weight gain or swollen ankles and legs because of a build-up of fluid.

If this happens, you need treatment immediately as it can be life-threatening. You will be given treatment until your liver recovers. You will need to stay in hospital for this treatment.