Alemtuzumab is sometimes used to treat chronic lymphocytic leukeamia (CLL) and prolymphocytic leukaemia (PLL). It may sometimes be used to treat other cancers. It is best to read this information with our general information about the type of cancer you have.

What is alemtuzumab?

Alemtuzumab is used to treat a type of blood cancer called chronic lymphocytic leukaemia (CLL). It can also be used to treat a rare type of leukaemia called prolymphocytic leukaemia (PLL). It is also sometimes given before a stem cell transplant to reduce the risk of graft versus host disease (GVHD). GVHD is when donor cells react against your own. 

Alemtuzumab belongs to a group of targeted therapy drugs known as monoclonal antibodies. Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How alemtuzumab is given

Alemtuzumab is only available when ordered by a haematologist for individual named patients. Some people may be given it as part of a clinical trial. Your haematologist can tell you if it is appropriate for you. Your haematologist can tell you if it is appropriate for you.

You will be given alemtuzumab at a day unit, as an outpatient or during a hospital stay.

During treatment you usually see a haematologist, a cancer nurse or specialist nurse, and a specialist pharmacist. A haematologist is a doctor who diagnoses and treats blood disorders and cancers. This is who we mean when we mention doctor, nurse or pharmacist in this information.

Before or on the day of treatment, a nurse or person trained to take blood (phlebotomist) will take a blood sample from you. This is to check that your blood cells are at a safe level to have treatment.

You will see a doctor or nurse before you have treatment. They will ask you how you have been feeling. If your blood results are okay, the pharmacist will prepare your targeted therapy. Your nurse will tell you when your treatment is likely to be ready.

Alemtuzumab can be given as a drip into a vein (intravenous infusion) or an injection under the skin (subcutaneous).

If you are having the treatment as an outpatient, you may need to stay in the unit for a few hours after the treatment. This is to make sure you do not have any signs of a reaction.

If you have subcutaneous injections and do not have problems with reactions, it may be possible to have your injections at home. A district or community nurse can give these injections. You will still come to the hospital regularly for check-ups and blood tests.

Your course of treatment


You may have alemtuzumab as a treatment for chronic lymphocytic leukaemia (CLL) or prolymphocytic leukaemia (PLL). You will have this as a subcutaneous injection or as a drip into a vein.

The first time you have alemtuzumab, you will have a low dose. This reduces the risk of you having a reaction to the drug. The doctor will increase the dose over the next few days until you are on the recommended dose. This usually takes from 3 to 7 days. After this you will have alemtuzumab 3 times a week, usually on a Monday, Wednesday and Friday.

Your doctor or nurse will explain more about how alemtuzumab is given. They can also tell you how long your treatment will last.

Stem cell transplant

Before a stem cell transplant, you may have alemtuzumab given in combination with other cancer drugs. It is given as a daily drip. You may have 1 to 5 treatments. You usually have it during a stay in hospital as an inpatient.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious or delayed side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your doctor or nurse can explain the risk of these side effects to you.

This treatment may cause delayed side effects. These can start weeks, months, or sometimes more than a year, after you finish treatment.

If you have any symptoms or side effects that start during treatment or after treatment finishes, contact your doctor or hospital straight away. Side effects can become serious if they are not treated.

Your patient alert card

Your doctor, nurse or pharmacist will give you a card with information about your treatment on it. It is important to always have the card with you during treatment and after treatment finishes. You should show it to any doctor or healthcare professional you need to see.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

Sometimes side effects can become serious very quickly. It is important to contact the hospital straight away if you have new symptoms or side effects.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Side effects while treatment is being given

Some people may have side effects while they are being given this treatment or shortly after they have it.

Allergic reaction

Some people have an allergic reaction while having this treatment. Before treatment, you will be given medicines to help prevent or reduce any reaction.

Signs of a reaction can include:

  • feeling hot or flushed
  • shivering
  • itching
  • a skin rash
  • feeling dizzy
  • a headache
  • feeling breathless or wheezy
  • swelling of your face or mouth
  • pain in your back, tummy or chest.

Your nurse will check you for signs of a reaction during your treatment. If you feel unwell or have any of these signs, tell them straight away. If you do have a reaction, it can be treated quickly.

Sometimes a reaction happens a few hours after treatment. If you develop any signs or feel unwell after you get home, contact the hospital straight away.

Redness or swelling at injection site

If you have this treatment as an injection under the skin, the area where you have the injection can become red and swollen (inflamed). This is usually mild and gets better within a few days. Your nurse will put the injection into a different site each time to help with this.

Common side 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 sometimes called neutropenia.

Your doctor may give you antibiotics and other drugs to try to stop you getting an infection. These are called prophylactic medicines.

An infection can be very serious when the number of white blood cells is low. It is important to get any infection treated as soon as possible. Contact the hospital straight away on the 24-hour contact number you have been given if:

  • your temperature goes over 37.5°C (99.5°F)
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection
  • your temperature goes below 36°C (96.8°F).

Symptoms of an infection include:

  • feeling shivery and shaking
  • a sore throat
  • a cough
  • breathlessness
  • diarrhoea
  • needing to pass urine (pee) a lot, or discomfort when you pass urine.

It is important to follow any specific advice your cancer treatment team gives you.

The number of white blood cells will usually return to normal before your next treatment. You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time, until your cell count increases.

Cytomegalovirus (CMV)

CMV is a common virus that many people have been infected with at some point in their lives. Usually CMV infection causes no symptoms, so most people do not know they have had it. Once the virus is in your system, it stays in your body for life. But normally it is inactive (dormant) and does not cause any problems.

If you have this virus, it may become active again while you are having alemtuzumab. Your doctor will give you medicines to help prevent this.

If CMV does become active, it is very important that it is treated. It can often be treated with tablets. Some people may need to have treatment in hospital on a drip (intravenous infusion).

Treatment for CMV can take several weeks. You may need treatment on more than one occasion while you are having alemtuzumab.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot.

If the number of platelets is low, you may bruise or bleed easily. You may have:

  • nosebleeds
  • bleeding gums
  • heavy periods
  • blood in your urine (pee) or stools (poo)
  • tiny red or purple spots on the skin that may look like a rash.

Tell your doctor if you have any unexplained bruising or bleeding. You may need a drip to give you extra platelets. This is called a platelet transfusion.

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. Red blood cells carry oxygen around the body. If the number of red blood cells is low, this is called anaemia. You may have symptoms such as:

  • pale skin
  • lack of energy
  • feeling breathless
  • feeling dizzy and light-headed.

Tell your doctor or nurse if you have these symptoms.

If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Skin changes

This treatment may affect your skin. It may cause a rash, which might be itchy. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day.

Always tell your doctor or nurse about any changes to your skin. They can give you advice and may prescribe creams or medicines to help. Skin changes usually improve when treatment finishes.

Feeling sick

Your doctor will give you anti-sickness drugs to help prevent or control sickness during your treatment. Take the drugs exactly as your nurse or pharmacist tells you. It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluids often and eat small amounts regularly. It is important to drink enough fluids. If you continue to feel sick, or are sick (vomit) more than once in 24 hours, contact the hospital as soon as possible. They will give you advice. Your doctor or nurse may change the anti-sickness drug to one that works better for you.

Feeling tired

Feeling tired is a common side effect of this treatment. It is often worse towards the end of treatment and for some weeks after it has finished. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy.

If you feel sleepy, do not drive or use machinery.


This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is usual for you, or having watery or loose stools. If you have a stoma, it will be more active than usual.

If you have diarrhoea:

  • try to drink at least 2 litres (3½ pints) of fluids each day
  • avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods
  • contact the hospital for advice.

Muscle or joint pain

You may get pain in your muscles or joints for a few days after treatment. If this happens, tell your doctor so they can give you painkillers. Tell them if the pain does not get better. Having warm baths and taking regular rests may help.

Changes in blood pressure

This treatment may affect your blood pressure and make it higher or lower than normal. Your nurse will check your blood pressure regularly during your treatment. Tell them if you begin to feel dizzy or develop any headaches. These can be signs of blood pressure changes.

Effects on the heart

This treatment can affect the way your heart works. Your doctor may do tests to see how well your heart is working. You may have these tests before, during, and sometimes after treatment.

Contact a doctor straight away if you:

  • have pain or tightness in your chest
  • feel breathless or dizzy
  • feel your heart is beating too fast or too slowly.

Other conditions can cause these symptoms. But it is important to get them checked by a doctor.

Effects on the thyroid gland

Pazopanib can affect the way thyroid gland works. It will go back to normal after treatment.

You will have regular blood tests to check your levels of hormones that are made by the thyroid. This side effect is usually mild and may not cause symptoms. Your doctor may give you drugs to take if your hormone levels are low. 

Less common side effects

Raised levels of uric acid (tumour lysis syndrome)

This treatment may cause the cancer cells to break down quickly. This releases uric acid (a waste product) into the blood. The kidneys usually get rid of uric acid, but may not be able to cope with large amounts. Too much uric acid can damage the kidneys. It can also cause swelling and pain in the joints, which is called gout.

Your doctor may give you tablets called allopurinol (Zyloric®) to help prevent this. Drinking at least 2 litres (3 ½ pints) of fluid a day will also help. You will have regular blood tests to check the uric acid levels.

Effects on the lungs

This treatment can cause changes to the lungs. Tell your doctor if you develop:

  • a cough
  • wheezing
  • breathlessness.

You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs.

Effects on the kidneys

This treatment can affect how your kidneys work. This is usually mild and goes back to normal after treatment finishes. You will have blood tests to check how well your kidneys are working.

It is important to drink at least 2 litres (3½ pints) of non-alcoholic fluid each day to help protect your kidneys.

Call your doctor or the hospital if you notice any blood in your urine (pee).

Effects on the liver

This treatment can affect how your liver works. You will have regular blood tests to check this. Your doctor may give you steroids if the blood tests show liver changes.

Sometimes liver changes can be serious. Contact the hospital straight away if you have any of these symptoms during treatment or after it finishes:

  • yellow skin or eyes
  • feeling very sleepy
  • dark urine (pee)
  • unexplained bleeding or bruising
  • loss of appetite.

You may need steroids or other treatments, and may be monitored until your liver recovers.

Eyesight changes

This treatment can affect your eyes and eyesight. If you have any of these symptoms during treatment or after it finishes, contact your doctor straight away:

  • sore or swollen eyes
  • eyes that are sensitive to light
  • changes to your eyesight.

You may need steroids or other treatments. You may also have an eye check with a specialist eye doctor (ophthalmologist).

Difficulty sleeping

This treatment can cause sleeplessness (insomnia) in some people. If you are finding it difficult to sleep, talk to your doctor or specialist nurse.

Effects on the immune system (cytokine release syndrome – CRS)

Immunotherapies cause the immune system to release proteins in the body. These proteins are called cytokines. High levels of cytokines may cause inflammation throughout the body. This is called cytokine release syndrome (CRS). It can affect some of the body’s functions.

Symptoms of CRS include:

  • fever
  • flu-like symptoms 
  • chills
  • headaches
  • a skin rash
  • joint or muscle aches
  • swelling
  • low blood pressure
  • coughing 
  • shortness of breath. 

Tell your doctor or nurse straight away if you have any of these symptoms. They will stop the blinatumomab infusion and treat any symptoms you have.

Other information

Blood irradiation

During and after treatment with alemtuzumab, any blood and platelets you are given should first be treated with radiation. This lowers the risk of the donated blood cells reacting against your own. It will not damage the blood or make you radioactive.

Your doctor will record in your medical notes that you should only be given irradiated blood products. They will also give you a card to carry in case you have treatment at another hospital. Always keep this card with you and remind your hospital team that you need irradiated blood or platelets.

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • throbbing pain, redness or swelling in a leg or arm
  • suddenly feeling breathless or coughing
  • sharp chest pain, which may be worse when you cough or take a deep breath.

If you have any of these symptoms, contact the hospital straight away on the 24-hour contact number you have been given. If you cannot get through to your doctor, call the NHS urgent advice number on 111.

A blood clot is serious, but it can be treated with drugs that thin the blood (anticoagulants). Your doctor or nurse can give you more information.

You can help reduce the risk of developing a blood clot by:

  • staying active during treatment
  • drinking plenty of fluids, especially water.

You may be given anticoagulants to help prevent a clot.

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.


Vaccinations can reduce your risk of getting certain infections. Your doctor or nurse may talk to you about having vaccinations.

Doctors usually recommend that people with cancer have a flu vaccination and a coronavirus vaccination. These are both inactivated vaccinations that can help reduce the risk of infection. People with weak immune systems can have these, as they are not live vaccinations.

If your immune system is weak, you need to avoid live vaccinations. This is because they can make you unwell. Live vaccines, such as shingles, contain a very weak version of the illness they are vaccinating you against. Your cancer doctor or GP can tell you more about live and inactivated vaccinations.


Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.


Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.


You are advised not to breastfeed while having this treatment, or for some time after treatment finishes. This is because the drugs could be passed to the baby through breast milk.

Your doctor or nurse can give you more information.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.

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 health professionals and people living with cancer.

    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.