Potential side effects

Any side effects you have will depend on the conditioning treatment you received. If you had reduced-intensity conditioning, the side effects may be less severe. Your hospital team will tell you what to expect and how the side effects can be managed.

Possible side effects include increased risk of infection, anaemia and bleeding due to low blood counts. You may also have:

  • sickness
  • reduced appetite
  • a sore mouth.

A dietician and your nurse will help you manage these. You may notice bowel or bladder changes as well as other common side effects of chemotherapy, such as hair loss and tiredness. Less common problems include graft failure or veno-occlusive disease.

You will have regular tests to check your general health and to monitor for side effects. Most side effects are worse when your blood count is at its lowest. As this goes up, your side effects will improve.

Long-term or late effects can include bone thinning, cataracts, or heart or lung changes. Always let your doctor know about any problems you experience.

Possible side effects of a donor stem cell (allogeneic) transplant

The side effects you have will depend on the type of conditioning treatment you have had. If you have had a reduced-intensity transplant, side effects may be less severe.

Your hospital team will tell you more about what to expect.

You’ll have blood samples taken every day, including a full blood count. Your blood cell numbers will be low for some time.

Risk of infection

The number of white blood cells in your blood (particularly a type called a neutrophil) will be low for some time. This is called neutropenia, or being neutropenic.

During this time, you’ll be at risk of infection, even from the bacteria that live on your skin and in your digestive system. These bacteria are normally useful to our bodies, but when the immune system isn’t working as well as usual, they may cause infections.

You will have drugs to prevent and treat infections. Treatment to prevent problems is called prophylaxis. The nurses and doctors will also take your temperature regularly, and check for signs of infection. They’ll ask you to tell them if you feel cold and shivery or have a sore throat, a cough, pain when passing urine or any other symptoms of an infection.

The hospital staff will try to protect you from possible sources of infection. But most people at some point will develop a high temperature and need antibiotics while their immune system recovers.

Keeping clean

Your room will be cleaned daily and your sheets will be changed. In most units, you’ll have a toilet and a shower of your own.

It’s important to keep your skin clean. The nurses will give you advice about showering and washing your hands. They can help you with personal care if you’re feeling very tired. They’ll also show you how to look after your mouth.

Being careful with food

During your time in hospital, there will be rules about what you can eat. This is to help you avoid food that contains bacteria. Each hospital will have its own guidelines. Your nurse or dietitian can explain them to you. They may include:

  • Avoid soft cheeses, pâté and unpasteurised foods.
  • Don’t eat lightly cooked or uncooked eggs.
  • Fruit and vegetables need to be washed and peeled.
  • Hot meals should be freshly prepared and well cooked (not reheated).
  • Avoid takeaway foods.


The ward nurses will tell your visitors how to protect you from infections. Visitors will have to wash their hands and wear an apron before going into your room. People who feel unwell or have an infection will be asked not to visit.


The number of red blood cells in your blood may be low at times. This is known as anaemia and 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.

For several months after your transplant, any blood (or platelets) you’re given will first be treated with radiation (irradiated). This is to prevent problems caused by white blood cells called lymphocytes, which may be in the donated blood. Irradiated blood isn’t radioactive and won’t harm you or anyone you come into contact with. Some people may continue to need any blood or platelet transfusions to be irradiated for the rest of their lives.


The number of platelets in your blood will be low after the transplant. You’re likely to need platelet transfusions to reduce the risk of bleeding or bruising. Platelets will be irradiated before they are given to you.

The doctors and nurses will examine you regularly for bruises or little red spots on the skin (petechiae). Let them know straight away if you have a nosebleed, bleeding gums or notice blood when you go to the toilet.

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.

Sore mouth

Chemotherapy and radiotherapy can cause painful mouth ulcers. If your mouth is sore, you’ll be given painkillers.

While your white blood cell count is low, you’re at risk of mouth infections including thrush, which is a fungal infection. Keeping your mouth clean is important to prevent infections that can spread to other parts of your body. The nurses will tell you how to look after your mouth and teeth.

Gently clean your teeth or dentures morning and night and after meals. Use a soft-bristled or children’s toothbrush. Your nurse might ask you to rinse your mouth regularly or use mouthwashes. It’s important to follow any advice you are given and to drink plenty of fluids.

Eating problems

During treatment, it’s important that you don’t lose too much weight. Try to eat small meals and snacks regularly.

If your appetite doesn’t improve, tell your nurse or dietitian.

They can help you add more calories into your diet. They may give you food supplements to try.

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

Some people may be fed through their central or PICC line with a special liquid feed called total parenteral nutrition (TPN). Once you start to eat more, the amount of food you’re given through the line is gradually reduced.


This can sometimes be severe. If you get diarrhoea, samples will be taken to check for infection. You’ll be given medicines to either treat any infection or help control the diarrhoea.

Let the nurses know if it doesn’t get better or if your bottom gets sore. Try to drink at least two litres (three and a half pints) of fluids every day. If you can’t manage this you may need fluids through a drip.

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 plenty of fluids – at least two litres (three and a half pints) each day. It’s also important to empty your bladder regularly and try to pass urine 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 passing urine.

Effects on the lungs

Having a transplant 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 existing breathing problems get worse.

Cytomegalovirus (CMV)

CMV is a viral infection that many people will have had as a child.

It feels like mild flu. The virus never fully leaves the body but is kept under control by the immune system. After a transplant, the virus can start to grow (reactivate) as the immune system is too weak to fight it. CMV infection can be serious and can affect different parts of the body including the lungs, bowel, eyes and occasionally the brain.

You’ll have a blood test to check for CMV before your transplant. Your donor will also be checked. Where possible, you will be matched with a donor with the same CMV status as you – either CMV positive or negative.

After your transplant, you’ll have regular blood tests to check for the virus. Even if you and your donor are both CMV negative, you’ll still be checked in case a new infection starts. If CMV levels begin to rise, finding out early makes the virus easier to control.

If the levels quickly start to rise after your transplant or become too high, you will have anti-CMV treatment. This may be tablets or sometimes drugs through a drip.

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.

Our section on coping with hair loss has useful information and tips on using hats, scarves and wigs.


You’ll probably feel very tired and spend a lot of time sleeping. Sometimes you may feel too tired to concentrate enough to read or even watch television. At times, you may not feel able to have visitors or to see them for too long. Let them know how you’re feeling so they don’t disturb you if you want to rest. You’ll probably get tired easily for some months after your treatment, but this will gradually get better.


Although you’re tired, it’s a good idea to try to do some gentle exercise, such as stretching. The physiotherapist can give you some suggestions. These help reduce the chances of getting a blood clot, and keep your muscles working and toned.

Some transplant units may have an exercise bike that you can use, when you’re feeling better and your blood counts have improved. Some units also have exercise programmes that you can continue with when you go home.

Starting to recover

Most side effects are worse when your full blood count is at its lowest – usually during the first two weeks after transplant.

When your blood count goes up, the side effects will start to improve. You’ll be at less risk of infection and won’t need so many blood and platelet transfusions. Your appetite will improve, and you’ll start to feel better.

Mixed chimerism

Chimerism is a measure of how well your donor’s cells have engrafted. You will have regular blood tests to measure the numbers of donor cells and your original cells. Your doctors might talk about this as a percentage (%). The aim is that you will get 100% (total) chimerism. This means your blood and bone marrow will be 100% the same as your donor’s.

If you develop a side effect called graft-versus-host disease (GvHD), you are more likely to have total chimerism. This is because the donor cells will have destroyed any remaining cells of your own and you will have total engraftment.

Some people will have a ‘mixed chimerism’. This is more common after reduced-intensity conditioning, when lower doses of drugs and radiation are given. This is because some of your own blood cells will survive this conditioning treatment. Mixed chimerism can improve over time but may be a sign of graft failure.

You will be carefully monitored after your transplant. If you are having immunosuppressive drugs , they may be stopped or reduced. Or you may be given treatment with donor lymphocyte infusions (DLI).

Donor lymphocyte infusions (DLI)

Lymphocytes are white blood cells and are part of the immune system. Your doctors may decide to treat you with donor lymphocytes. These will be from your original donor.

They may have been saved when cells were first collected from your donor. Otherwise, the donor may be asked to donate again. No injections are needed before this procedure. The lymphocytes are collected by a cell separator machine.

The lymphocytes are then given to you by a drip into your line. The lymphocytes should destroy any remaining cancer cells and improve your mixed chimerism. The aim is for all your bone marrow cells to be from your donor. The main risk of DLI is that you might develop GvHD. Your doctor will talk to you about any risks.

Less common problems

Graft failure

Sometimes the donor cells don’t make enough new blood cells. This is known as graft failure. If the graft fails to make enough new blood cells, it can lead to repeated infections, bruising, bleeding and anaemia. Total graft failure is rare, and the only way to treat it is with another infusion of stem cells from the donor.

Without this, a person will only live for a short time.

Veno-occlusive disease (VOD)

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 fluid build-up.

If this happens, you will 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.

Long-term and late effects of a donor stem cell (allogeneic) transplant

Some side effects of treatment can take a long time to improve or may become permanent (long-term effects). Other effects can develop years after treatment has finished (late effects).

Some problems vary from being mild to more serious.

They may be due to the conditioning treatment you had before your transplant or because your immune system doesn’t work as well as before. Always let your doctor know about any problems you have. Possible long-term or late effects include the following.


There’s a risk a cataract might develop in the lens of your eye. This can make your vision cloudy, blurred or dim. Let your doctor know if you have any problems with your vision. Cataracts can usually be treated with a small operation.

Low levels of the thyroid hormone thyroxine (hypothyroidism)

You’ll have blood tests to check your thyroxine levels. If you develop this condition, you will be given thyroxine tablets.

Bone thinning (osteoporosis)

Steroids and low levels of sex hormones can increase your risk of developing osteoporosis. Let your doctor know if you have any problems with your bones as vitamins or other supplements can help with this. Weight-bearing exercise, such as walking and dancing, also help keep your bones healthy.

Lung changes

Always tell your doctor if you develop wheezing, a cough, or feel breathless. You should also let them know if any existing breathing problems get worse. If necessary, they can arrange for you to have tests to check your lungs.

Heart changes

After a transplant, your heart may be affected. You may have tests to see how well your heart is working. If you have pain or tightness in your chest or feel breathless, or notice changes to your heartbeat, tell a doctor straight away. These symptoms can be caused by other conditions but it’s important to get them checked by a doctor.

Increased risk of cancer

Having a transplant can increase your risk of developing a second cancer. You will be closely monitored by your transplant team so any problems with your health can be picked up and treated early. You can reduce your risk by not smoking, eating healthily, taking regular exercise, drinking sensibly and protecting yourself from the sun. It’s also good to take part in any screening programmes that you’re offered for bowel, breast or cervical cancer.

Back to Side effects of allogeneic (donor) stem cell transplants