Alemtuzumab is a targeted therapy drug. It is used to treat chronic lymphocytic leukaemia (CLL) and prolymphocytic leukaemia (PLL). CLL and PLL are cancers of the white blood cells.

Alemtuzumab can be given as an injection under the skin, or as a drip (infusion) into a vein. You usually have it as an outpatient. Your cancer doctor or nurse will tell you how often you will have it.

Like all targeted therapy drugs, alemtuzumab can cause side effects. Some side effects can be serious, so it is important that you read the detailed information below.

How targeted therapy affects people varies from person to person. It is important to read about the side effects so that you know what to expect. Your healthcare team can talk to you more about this and give you advice on how to manage any side effects.

Tell your doctor or nurse straight away if you:

  • have a temperature
  • feel unwell
  • have severe side effects, including any we do not mention here

If you need to seek medical attention for any reason other than cancer, always tell the healthcare staff that you are having this treatment.

What is alemtuzumab

Alemtuzumab is a targeted therapy. It belongs to a group of cancer 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.

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 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.

You will see a haematologist and a chemotherapy nurse or specialist nurse throughout your treatment with alemtuzumab. This is who we mean when we mention doctor or nurse in this information.

How targeted therapies work

This animation shows how targeted therapies work and what effect they have on the body.

About our cancer information videos

How targeted therapies work

This animation shows how targeted therapies work and what effect they have on the body.

About our cancer information videos

How alemtuzumab is given

Alemtuzumab is given as either:

  • an injection under the skin (subcutaneous injection)
  • a drip into a vein (intravenous infusion).


If you have alemtuzumab as a treatment for CLL, you will usually have it as a subcutaneous injection. You have the injections three times a week, usually on a Monday, Wednesday and Friday.

Sometimes alemtuzumab is given as a drip to treat CLL or PLL. For the first few treatments, you will be given it daily. You will then have it three times a week.

When you start alemtuzumab, you may start on a low dose. The doctor increases the dose with each treatment until you reach the recommended dose. This reduces the risk of you having a reaction to the drug. Your doctor or nurse will explain more about this to you. They can also tell you how long your treatment will last.

You usually have alemtuzumab in the chemotherapy day unit. 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 to it. 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 them. You will still need to come to the hospital regularly for check-ups and blood tests.

Stem cell transplant

Before a stem cell transplant, alemtuzumab is given as a daily drip. You may have one to five treatments. You will usually have it during a stay in hospital as an inpatient in the transplant ward.

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 haven’t 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.

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
  • 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 can happen 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.

Risk of infection

This drug can reduce the number of white blood cells in your blood. This will make you more likely to get an infection. When the number of white blood cells is low, it is called neutropenia.

Contact the hospital straight away on the contact number you have been given if:

  • your temperature goes over 37.5°C (99.5°F) or over 38°C (100.4°F), depending on the advice given by your chemotherapy team
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection – this can include:
    • feeling shaky
    • a sore throat
    • a cough
    • diarrhoea
    • needing to pass urine a lot.

You will have blood taken regularly whilst having this treatment. This is to check that your blood cells are at a healthy level to check you are well throughout your treatment.

Your doctor will also prescribe some medicines for you to take to help prevent infections during your treatment. You will usually continue these for some time after you finish the treatment.

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 to have treatment on more than one occasion while you are having alemtuzumab.

Redness or swelling at injection site

If you have alemtuzumab 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.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells which help the blood to clot. Tell your doctor if you have any bruising or bleeding that you can’t explain. This includes nose bleeds, bleeding gums, blood spots or rashes on the skin. If your platelet count is very low, you may need a drip to give you extra platelets (platelet transfusion).

Feeling sick

This is usually mild, but your doctor can prescribe anti-sickness drugs to help. Tell your doctor if it does not get better.

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 this happens, tell your doctor or nurse. They can give you painkillers.

Feeling tired

Feeling tired is a common side effect. 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 operate 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.


If you have diarrhoea, contact the hospital for advice. Try to drink at least 2 litres (3½ pints) of fluids every day. It can help to avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods.

Muscle and joint pain

You may get pain in your joints or muscles during treatment. Tell your doctor if this happens so they can prescribe painkillers. Let them know if the pain does not get better. Try to get plenty of rest. Taking regular warm baths may help.

High blood pressure and fast heartbeat

Alemtuzumab may cause high blood pressure. Your nurse will check it regularly during your treatment. Tell them if you begin to feel dizzy or develop any headaches. If you notice your heart beating faster, let you doctor or nurse know straight away.

Coping with fatigue

Denton describes how he coped with fatigue (tiredness) during his treatment for prostate cancer.

About our cancer information videos

Coping with fatigue

Denton describes how he coped with fatigue (tiredness) during his treatment for prostate cancer.

About our cancer information videos

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.

Other medicines

Some medicines, including those that you can buy in a shop or chemist, can be harmful to take when you are having alemtuzumab. Tell your doctor about any medicines you are taking, including over-the-counter drugs, complementary therapies and herbal drugs.


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


Your doctor will advise you not to become pregnant or father a child while taking alemtuzumab as not enough is known about its effect on the developing baby. It is important to use effective contraception while having this drug and for a few months afterwards. You can discuss this with your doctor or specialist nurse.


Alemtuzumab may affect your fertility (being able to get pregnant or father a child ). If you are worried about this, you can talk to your doctor or nurse before treatment starts.


Women are advised not to breastfeed while having this treatment and for some time afterwards. This is because the drugs could be passed to the baby through breast milk.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that 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 this treatment.