Alemtuzumab
Alemtuzumab is a cancer drug. It is used to treat some types of blood cancer.
What is alemtuzumab?
Alemtuzumab is a type of targeted therapy drug called a monoclonal antibody.
Alemtuzumab is used to treat some types of blood cancer.
It is best to read this information with our general information about targeted therapy drugs and the type of cancer you have.
If it is suitable for you, your doctor can apply for alemtuzumab through a patient access scheme. Or it may be available as part of a clinical trial.
Your cancer team will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.
More information about this treatment
This information is correct at time of publishing. But sometimes the types of cancer this treatment is used for, or treatment side effects, may change between revision dates.
You can talk to your cancer team if you want more detailed information about this treatment. Or visit the electronic Medicines Compendium (eMC) website, which has patient information leaflets (PIL) for individual drugs.
How alemtuzumab is given
You usually have alemtuzumab in a day unit or clinic as an outpatient, or during a stay in hospital.
During a course of treatment, you will meet someone from your cancer team, such as a:
- blood cancer doctor (haematologist)
- specialist nurse
- specialist pharmacist.
This is who we mean when we mention doctor, nurse or pharmacist in this information.
During your course of treatment, you will have regular blood tests. This is to check that it is safe for you to have treatment.
You will meet with a doctor, nurse or pharmacist before you have treatment. They will talk to you about your blood results and ask how you have been feeling. If your blood results are okay and you are well enough for treatment, the pharmacy team will prepare your targeted therapy.
You have alemtuzumab as a drip into a vein (intravenous infusion). You may have it with other cancer drugs.
If you are having 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.
Your nurse will give you alemtuzumab through 1 of the following:
- a cannula – a short, thin tube the nurse puts into a vein in the arm or hand
- a central line – a fine tube that goes under the skin of the chest and into a vein close by
- a PICC line – a fine tube that is put into a vein in the arm and goes up into a vein in the chest
- an implantable port (portacath) – a disc that is put under the skin on the chest or arm and goes into a vein in the chest.
Your course of treatment
You usually have a course of several treatments over a few weeks or months. Your cancer team will discuss your treatment plan with you.
The first time you have alemtuzumab, you usually have a low dose. This reduces the risk of you having a reaction to the drug. The doctor increases 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 have alemtuzumab 3 times a week, usually on a Monday, Wednesday and Friday.
Sometimes, alemtuzumab is given in combination with other drugs.
Your doctor or nurses will explain more about how alemtuzumab is given. They can also tell you how long your treatment will last.
About side effects
We explain the most common side effects of this treatment here. We also include some that are less common.
You may get some of the side effects we mention, but you are unlikely to get all of them. And you may have some side effects, including rarer ones, that we have not listed here.
Other cancer treatments may cause different side effects. If you are also having other cancer treatment, you may have other side effects.
Always tell your doctor, nurse or pharmacist about any side effects you have. They can give you:
- drugs to help control some side effects
- advice about managing side effects.
It is important to take any drugs exactly as explained. This means they will be more likely to work for you.
Serious and life-threatening side effects
Some cancer treatments can cause serious side effects. Sometimes, these may be life-threatening. Your doctor, nurse or pharmacist can explain the risk of these side effects to you.
Your patient alert card
They will also give you a card with information about your treatment. It is important to keep the card with you during treatment and after treatment ends. You should show it to any doctor or healthcare professional caring for you.
Contact the hospital
Your doctor, nurse or pharmacist will give you 24-hour contact 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.
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. The first infusion is the most likely to cause a reaction, so it is usually given more slowly than later treatments. Before treatment, you will have 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 or sick
- 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 infusion. If you feel unwell or have any of these signs, tell them straight away. If you do have a reaction, they can treat it quickly.
Sometimes a reaction happens a few hours after treatment. If you develop any of these signs or feel unwell after you get home, contact the hospital straight away on the 24-hour number.
Always call 999 if swelling happens suddenly or you are struggling to breathe.
Very common side effects
These side effects happen to 10 or more people in every 100 people (10% or more) who have this treatment.
Risk of infection
This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If your white blood cell count is low, you may be more likely to get an infection. A low white blood cell count is called neutropenia.
An infection can be very serious when the number of white blood cells is low. Your doctor may give you antibiotics and other drugs to take during this treatment. These may help reduce your risk of getting an infection.
But it is still important to get any infection treated as soon as possible. If you have any of the following symptoms, contact the hospital straight away on the 24-hour number:
- a temperature above 37.5°C
- a temperature below 36°C
- you feel unwell, even with a normal temperature
- you have symptoms of an infection.
Symptoms of an infection include:
- feeling shivery and shaking
- a sore throat
- a cough
- breathlessness
- diarrhoea
- needing to pass urine (pee) often, or discomfort when you pass urine.
It is important to follow any specific advice your cancer treatment team gives you.
Your white blood cell count 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.
You may be given a drug called G-CSF. This encourages the body to make more white blood cells. You have it as a small injection under the skin.
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.
Skin changes
This treatment may affect your skin. It might feel dry. You may develop a rash, which may be itchy. Always tell your doctor, nurse or pharmacist about any skin changes. They can give you advice or prescribe creams or medicines to help.
If your skin feels dry, try using soap-free cleansers and unperfumed moisturising cream every day.
Headaches
This treatment may cause headaches. If you have headaches, tell your doctor, nurse or pharmacist. They can give you advice about painkillers that may help. Tell them if the headache does not get better, or gets worse.
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 ends. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can help you feel less tired.
If you feel sleepy, do not drive or use machinery.
Feeling sick
Your doctor, nurse or pharmacist will prescribe anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as they tell you to, even if you do not feel sick. It is easier to prevent sickness than to treat it after it has started.
If you feel sick, take small sips of fluid often and eat small amounts regularly. It is important to drink enough fluids. If you continue to feel sick, or if you are sick (vomit) 1 to 2 times in 24 hours, contact the hospital on the 24-hour number as soon as possible. They will give you advice. They may change your anti-sickness treatment. Let them know if you still feel sick.
Effects on the heart
This treatment can affect how the heart works. You may have tests to check how well your heart is working. These may be done before, during and after treatment.
If the treatment is causing heart problems, your doctor may change the type of treatment you are having.
Contact the hospital straight away on the 24-hour number if you have any of these symptoms during or after treatment:
- breathlessness
- dizziness
- changes to your heartbeat (palpitations)
- swollen feet and ankles.
Other conditions can cause these symptoms, but it is important to get them checked by a doctor.
Always call 999 if you have:
- chest pain, pressure, heaviness, tightness or squeezing across the chest
- difficulty breathing.
Effects on the thyroid
Other side effects
These side effects happen to less than 10 in 100 people (less than 10%) who have this treatment. Some of them are much rarer than this but they are still important to know about. Rare means a side effect that happens to less than 1 in 1,000 people (less than 0.1%).
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, brown or purple spots that may look like a rash – these spots can be harder to see if you have black or brown skin.
If you have any unexplained bruising or bleeding, contact the hospital straight away on the 24-hour number. 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 feel:
- very low in energy
- breathless
- dizzy and light-headed.
If you have these symptoms, contact the hospital straight away on the 24-hour number. You may need treatment for anaemia. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.
Sore mouth and throat
This treatment may cause a sore mouth and throat. You may also get mouth ulcers. This can make you more likely to get a mouth or throat infection. Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.
Contact the hospital straight away on the 24-hour number, if:
- a sore mouth or throat affects how much you can drink or eat
- your mouth, tongue, throat or lips have any blisters, ulcers or white patches.
They can give you advice, and mouthwash or medicines to help with the pain or to treat any infection. Follow their advice and make sure you:
- drink plenty of fluids
- avoid alcohol and tobacco
- avoid food or drinks that irritate your mouth and throat.
Tummy pain
You may get pain in your tummy (abdomen), or have indigestion. Your doctor, nurse or pharmacist can give you advice or treatment to help. Contact the hospital straight away on the 24-hour number if your symptoms do not go away, or get worse.
Diarrhoea
This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is normal for you, or having watery or loose stools. You may also have stomach cramps. If you have a stoma, it may be more active than usual.
If you are passing loose stools 3 or more times a day and this is not normal for you, contact the hospital as soon as possible on the 24-hour number. Follow the advice they give you about:
- taking anti-diarrhoea medicines
- drinking enough fluids to keep you hydrated and to replace lost salts and minerals
- any changes to your diet that might help.
They might also ask you for a specimen of your stool to check for infection.
Mood changes or difficulty sleeping
You may have some mood changes during this treatment. You may feel anxious, low or depressed. Or you may have difficulty sleeping. Tell your doctor or nurse if you notice any changes.
Changes to periods
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, nurse or pharmacist. They can give you painkillers and advice. They can also tell you if any of the painkillers you usually take are suitable.
Tell them if the pain does not get better. Having warm baths and resting regularly may help.
Fluid build-up
This treatment can cause a build-up of fluid in the body. This will slowly get better after treatment ends. Contact the hospital on the 24-hour number if you:
- are gaining weight
- have swelling in your face, legs or ankles.
They can give you advice and treatment to help.
Effects on the liver and kidneys
This treatment can affect how your kidneys or liver work. This is usually mild and goes back to normal after treatment ends. You will have blood tests to check how well your kidneys and liver are working. Contact the hospital on the 24-hour number if you:
- have blood in your urine (pee)
- are passing less urine or peeing less often than usual.
Drinking fluids also helps protect your kidneys. The advice is usually to try to drink at least 2 litres (3½ pints) of fluid each day. But follow any advice from your doctor, nurse or pharmacist about how much is right for you.
Effects on the lungs
This treatment can cause inflammation of the lungs. This is called pneumonitis. Contact the hospital straight away on the 24-hour number if you notice any of these changes during treatment or after it ends:
- breathlessness
- a cough that does not go away
- wheezing
- a fever, with a temperature over 37.5°C.
You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs. You may need steroids or other treatments.
Effects on the eyes
Your eyes may become watery and feel sore. Your doctor, nurse or pharmacist can give you advice and eye drops to help with this.
Contact the hospital on the 24-hour number if:
- your eyes get red and inflamed (conjunctivitis)
- you have pain in your eyes
- you notice any change in your vision.
Cytokine Release Syndrome (CRS)
Cytokines are chemical messengers that increase the effects of the immune system. This treatment causes the body to release large amounts of cytokines. This can cause flu-like symptoms, which can range from mild to severe. Some people may be monitored and treated in intensive care until this improves.
Symptoms include:
- a high temperature
- a fast heart rate
- low blood pressure and dizziness
- muscle and joint pain
- diarrhoea
- feeling sick and being sick
- difficulty breathing.
There are treatments that can help manage these side effects.
Tumour lysis syndrome (TLS)
Some people are at risk of developing a condition called tumour lysis syndrome (TLS). The risk is highest at the beginning of treatment. TLS happens when treatment makes large numbers of cancer cells die and break down quickly. This releases lots of waste products into the blood and can affect the kidneys and heart.
TLS can be prevented or treated. You will have regular blood tests to check for TLS. You may have:
- extra fluids through a drip
- medicines such as allopurinol tablets or rasburicase through a drip.
Drinking at least 2 litres (3½ pints) of fluid a day will also help.
Effects on the brain
Rarely, this treatment causes a brain condition that can be serious. You can make a full recovery from this. But it must be diagnosed and treated quickly.
This condition can cause:
- a headache that does not get better
- drowsiness or confusion
- changes in eyesight
- fits (seizures).
If you have any of these symptoms, it is important to either:
- contact the hospital straight away on the 24-hour number
- go to the hospital straight away.
You should not drive yourself to hospital.
Other important 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. Contact the hospital straight away on the 24-hour number if you have any of these symptoms during or after treatment:
- throbbing pain or swelling in a leg or arm
- reddening of the skin in the area – if you have black or brown skin, this can be harder to notice, but the skin might become darker
- suddenly feeling breathless or coughing.
Always call 999 if you have:
- chest pain
- difficulty breathing.
A blood clot is serious, but it can be treated with drugs called anticoagulants. These thin the blood. Your doctor, nurse or pharmacist can give you more information about preventing and treating blood clots.
Other medicines
Some medicines can affect how this treatment works or be harmful while you are having it. Always tell your cancer doctor, nurse or pharmacist about any drugs you are taking or planning to take, such as:
- medicines you have been prescribed
- medicines you buy in a shop, pharmacy or online
- vitamins or supplements
- herbal drugs and complementary or homeopathic therapies
- recreational drugs – for example, cannabis.
Vaccinations
Cancer doctors usually recommend that people with cancer have vaccinations for flu and coronavirus (covid). They may also recommend other vaccines, such as Shingrix® for shingles. These all help reduce your risk of serious illness from these infections. Most people can have these vaccines, including people with weak immune systems.
You should not have live vaccines if your immune system is weak. This includes if you are having or recently had chemotherapy, radiotherapy or other cancer treatments that affect your immune system. Live vaccines can make you unwell because they contain a very weak version of the illness they protect you against. There are several live vaccines, including the yellow fever vaccine.
It is important to ask your doctor, nurse or pharmacist for advice about having vaccinations. They can explain what vaccines are right for you and when it is best to have them.
Contraception
Your doctor, nurse or pharmacist will advise you not to get pregnant or make someone pregnant while having this treatment and for some time afterwards. The drugs may harm a developing baby.
It is important to use contraception to prevent pregnancy. Follow their advice about:
- what types of contraception to use
- how long after treatment you should continue to use contraception.
You may be asked to take a pregnancy test before starting treatment.
Breastfeeding
You are advised not to breastfeed while having this treatment, or for some time after treatment ends. This is because the drugs could be passed to the baby through breast milk.
Your doctor, nurse or pharmacist can give you more information.
Fertility
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.
Medical and dental treatment
If you need medical treatment for any reason other than cancer, always tell the healthcare professional that you are having cancer treatment. Give them the contact details for your cancer doctor or cancer team so they can ask for advice.
If you have appointments with a dentist, always tell them you are having cancer treatment. Talk to your cancer team before you have any dental treatment.
About our information
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer.
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References
Visit the electronic Medicines Compendium (eMC) to download a Patient Information Leaflet (PIL) for more detailed information. The leaflet lists all known side effects.
Date reviewed

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