Alemtuzumab is a targeted therapy used to treat chronic lymphocytic leukaemia and prolymphocytic leukaemia. It is sometimes used before a stem cell transplant.

What is alemtuzumab?

Alemtuzumab is a targeted therapy drug used to treat a type of blood cancer called chronic lymphocytic leukaemia (CLL). It is also used to treat a rare type of leukaemia called prolymphocytic leukaemia (PLL).

It is 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. 
It is best to read this information with our general information about the type of cancer you have.

Alemtuzumab belongs to a group of targeted therapy drugs known as monoclonal antibodies. It works by locking on to a protein found on the surface of a type of white blood cell. This triggers the body’s immune system to attack these blood cells and destroy them.

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 cancer doctor for individual named patients. Some people may have it as part of a clinical trial. Your haematologist can tell you if it is appropriate for you.

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

During treatment you usually see a cancer doctor, a cancer nurse or specialist nurse, and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

Your doctor or nurse will take blood samples during your treatment. 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.

You can have alemtuzumab as a drip into a vein (intravenous infusion) or as 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.


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 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.

Possible 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 and life-threatening side effects

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

Contact the hospital

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

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can talk to your haematologist or specialist nurse for more information about this drug.

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 have medicines to help prevent or reduce any reaction.

Signs of a reaction can include:

  • feeling hot or flushed
  • a skin rash
  • itching
  • shivering
  • feeling dizzy
  • a headache
  • feeling breathless
  • fast heart beat
  • swelling of your face or lips
  • 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.

The symptoms of a reaction are most common in the first week, but will often improve after this.

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.

Feeling sick

Your doctor can give you anti-sickness drugs to help prevent sickness. Take the drugs exactly as your nurse or pharmacist tells you.

If you feel sick, take small sips of fluids and eat small amounts often. If you continue to feel sick, or if you vomit more than once in 24 hours, contact the hospital. They can give you advice and change the anti-sickness drug to one that works better for you.

Skin changes

This treatment may affect your skin and can cause a rash. 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 skin changes. They can give you advice and may prescribe creams or medicines to help.


This treatment may cause headaches. If you have headaches, tell your doctor. They may give you painkillers to help.

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.

Breathlessness or a cough

Some people may become breathless or have a cough. Let your doctor know if this happens. They can give you medicines to help. Tell your doctor if your breathing gets worse.


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. If this happens, tell your doctor so they can give you 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.

Heart problems

Sometimes this treatment can affect the heart. You may notice your heart is beating too fast or you may feel breathless or dizzy. Tell your doctor straight away if this happens.

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

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.

Raised levels of uric acid (tumour lysis syndrome)

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

Your doctor may give you allopurinol (Zyloric®) tablets to help prevent this. Drinking at least 2 litres (3½ pints) of fluids a day will also help. You will have regular blood tests to check the uric acid levels.

Other information

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.

Blood irradiation

During and after treatment with alemtuzumab, any blood and platelets you have 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. Before having a transfusion remind your hospital team that you need irradiated blood or platelets.

Other medicines

Some medicines can affect your treatment or be harmful when you are having it. This includes medicines you can buy in a shop or chemist. Tell your cancer doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies.


You should not have any live vaccines during treatment and for at least six months afterwards. Live vaccines include:

  • BCG (tuberculosis)
  • yellow fever
  • measles
  • mumps
  • rubella
  • liquid typhoid
  • poliomyelitis
  • shingles
  • MMR (combined measles, mumps and rubella)
  • rotavirus
  • the nasal flu vaccine.

You should try to avoid close contact with children for 7 days after they have received the nasal flu vaccine. You should also avoid close contact with children or babies for 4 weeks after they have been immunised against polio (using the oral vaccine) or rotavirus. If you have any questions about this, speak to your doctor or nurse.


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.