Alemtuzumab (Campath, MabCampath)

Alemtuzumab is a type of targeted cancer drug. It’s a treatment for some types of leukaemia and skin lymphoma. And may be used as part of a stem cell transplant.

What is alemtuzumab?

Alemtuzumab is a type of targeted cancer drug called a monoclonal antibody. It is a treatment for several cancers including:

  • chronic lymphoblastic leukaemia (CLL)
  • a rare type of leukaemia called T-cell prolymphocytic leukaemia (T-PLL)
  • skin lymphoma

Doctors also use alemtuzumab as part of a stem cell transplant to reduce the risk of a complication called graft versus host disease (GVHD Open a glossary item).

Alemtuzumab is pronounced A-lem-TOO-zoo-mab.

How does alemtuzumab work?

Alemtuzumab is a monoclonal antibody that targets a protein called CD52 on the surface of most types of white blood cells. The alemtuzumab sticks to all the CD52 proteins it finds. Then the immune system picks out the marked cells and kills them.

How do you have alemtuzumab?

You usually have alemtuzumab as a drip into your bloodstream (intravenously). You may also have it as an injection under the skin (subcutaneously).

Into your bloodstream

You might have treatment through a long plastic tube that goes into a large vein in your chest. The tube stays in place throughout the course of treatment. This can be a:

  • central line
  • PICC line
  • portacath

Injection under your skin

You usually have injections under the skin (subcutaneous injection) into the stomach and thigh.

You might have stinging or a dull ache for a short time after this type of injection. The skin in the area may go red and itchy for a while. To help relieve symptoms you can put an ice pack on to the injection site for 15 to 20 minutes, several times a day.

How often do you have alemtuzumab?

For chronic lymphocytic leukaemia (CLL) and T-cell prolymphocytic leukaemia (T-PLL)

You have alemtuzumab as a drip (an infusion) over 2 hours. You usually have treatment 3 times a week, for between 4 and 12 weeks. 

You start on a low amount (dose) and the doctor gradually increases the dose until you are having the recommended amount. This is called dose escalation. Doctors do this because some people react to the treatment. By gradually increasing the dose you are less likely to react.

Rarely for CLL, you might also have alemtuzumab as an injection under the skin.

For skin lymphoma

You have alemtuzumab as an injection under the skin. You have this 3 times a week for up to 12 weeks.

As part of a stem cell transplant

You might have alemtuzumab as an infusion over 2 hours for up to 5 days. This depends on your cancer type and the kind of stem cell transplant you’re having.  


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

What are the side effects of alemtuzumab?

Side effects can vary from person to person. They also depend on what other treatments you're having. 

When to contact your team

Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better. 

Contact your advice line immediately if you have signs of infection, including a temperature above 37.5C or below 36C.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects. But you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

Reaction to the infusion

Some people have a reaction to alemtuzumab. This reaction is most likely to happen in the first week of having this drug. Symptoms might include feeling or being sick, low blood pressure making you feel weak and faint, fever, chills, diarrhoea, rash, facial swelling or difficulty breathing.

Rarely, you might have a sever allergic reaction to the drug which can be life threatening. 

Your nurse keeps a close eye on you when you have the drug and gives you medicine beforehand to try to prevent a reaction. Tell them straight away if you have any symptoms or don’t feel quite right. They will slow down or stop your drip for a while.

Increased risk of infection

Increased risk of getting an infection is due to a drop in white blood cells. Symptoms include a change in temperature, aching muscles, headaches, feeling cold and shivery and generally unwell. You might have other symptoms depending on where the infection is.

Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection. 

Cytomegalovirus (CMV)

Cytomegalovirus is a common virus that is closely related to the herpes virus. It can remain inactive in your body for many years. But in some people, alemtuzumab can cause it to become active again (reactivate) due to your lowered immune system. This usually happens about 3 to 8 weeks after you started the drug.

Symptoms include flu-like symptoms such as headaches, muscle aches (myalgia), a high temperature, and shivering. Tell your doctor or nurse if you have any of these symptoms.

You have regular blood tests to check for this virus. It’s important you have treatment if it does come active again.

Breathlessness and looking pale

You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.

Bruising, bleeding gums or nose bleeds

This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. You may have nosebleeds or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae).

You might bleed from other parts of your body, so you might find blood in your wee or poo for example. Or you might have unusually heavy periods.

Rarely you might have a bleed on the brain. Symptoms include a headache, feeling or being sick, confusion, seizures (fits) or loss of eyesight.

Call your advice line if you have any bleeding.

Tiredness and weakness

You might feel very tired and as though you lack energy.

Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.

Sweating more than normal

This drug can cause you to sweat more than normal. Let your doctor or nurse know if this happens.


Tell your doctor or nurse if you keep getting headaches. They can give you painkillers to help and check for causes.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.

Skin problems

Skin problems include a raised, red, itchy skin rash.

Less commonly alemtuzumab can cause blisters and a sudden reddening of your skin (flushing).

Your skin usually goes back to normal when your treatment finishes. Your nurse will tell you what products you can use on your skin to help.

Loss of appetite and weight loss

You might lose your appetite for various reasons while having cancer treatment. Sickness, taste changes or tiredness can put you off food and drinks.

Less commonly you may lose weight. You can talk to a dietitian if you are concerned about your appetite or weight loss


Contact your advice line if you have diarrhoea, such as if you've had 4 or more loose watery poos (stools) in 24 hours. Or if you can't drink to replace the lost fluid. Or if it carries on for more than 3 days.

Your doctor may give you anti diarrhoea medicine to take home with you after treatment. Eat less fibre, avoid raw fruits, fruit juice, cereals and vegetables, and drink plenty to replace the fluid lost.

Pain in your body, muscles and joints

You might feel some pain from different areas of your body such as your tummy (abdomen), bones, muscles and at the site of injection if you have the drug this way.

You might get pain in your back, chest and joints, but this is less common. 

Speak to your doctor or nurse about what painkillers you can take to help with this.


This drug might make you feel dizzy. Don’t drive or operate machinery if you have this.

Abnormal feeling in your body

You may have an abnormal feeling (sensation) in your body, particularly in your legs and feet, such as burning, prickling or aching.

Less commonly you may have pins and needles or be less sensitive to touch, vibrations or the cold.

This is usually temporary and improves after treatment. Tell your doctor if you have these symptoms.

Difficulty breathing or a cough

It is important to tell your doctor or nurse if you have a cough or are breathless. It may be a sign of infection or inflammation in the lungs.

Less commonly this can cause your body not to get enough oxygen to the rest of your body. You might feel confused, restless, your breathing may get faster, and your heartbeat might increase. You might also get changes to the colour of your skin such as a bluish colour. This is called hypoxia. Some lung problems can also cause a high pitched whistling sound (wheeze).

Let your medical team know straight away if you get any of these symptoms.

Blood pressure changes

Tell your doctor or nurse if you feel light headed or dizzy as it might be a sign that you have a low blood pressure. Less commonly you might get high blood pressure. You nurse checks your blood pressure regularly.

Occasional side effects:

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

  • difficulty sleeping or you might find the opposite and want to sleep more than usual
  • sore mouth and ulcers which can be painful, so you might find it difficult to eat and drink – let your team know if this happens
  • loss of taste
  • generally feeling unwell
  • fast heart rate
  • difficulty going for a poo (constipation)
  • lack of fluid in the body (dehydration)
  • indigestion - symptoms include heartburn, bloating and burping
  • changes in mood such as feeling anxious, confused or very low (depressed)
  • fluid build up of different parts of the body (oedema). Rarely you might have a build up of fluid in the tummy (abdomen).
  • feeling of spinning or loss of balance (vertigo)
  • changes to how your liver works – you have regular blood tests to check this
  • a blood condition called autoimmune haemolytic anaemia where red blood cells are destroyed faster than they are made
  • feeling shaky or trembling (tremor)
  • chest tightness or pain due to narrowing of the blood vessels to the heart
  • eye problems such as an eye infection (conjunctivitis), causing the eye to feel gritty, sticky and look red. Or you might have inflammation of the tissues inside the eyeball. Rarely there might be damage to the nerve that carries information between your eye and brain.
  • low levels of minerals and salts such as calcium and sodium in the blood – you have regular blood tests to check this

Rare side effects

These side effects happen in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:

  • changes to your heartbeat’s rhythm or rate- you might feel tired, weak, dizzy or short of breath. Rarely this drug can cause a heart attack – symptoms include chest pain that can spread to your jaw, neck, arms and back.
  • a condition where the body makes too much of a hormone that controls the amount of water in your body - this means you hold on to too much water
  • high thyroid levels that can make you feel anxious, irritable, hyperactive, thirsty, itchy, tired, and you might have trouble sleeping
  • inflammation of the gut which can cause diarrhoea that may have blood in it, cramps, bloating, feeling or being sick, loss of appetite, weight loss, pain and fever
  • inflammation of your pancreas – symptoms include severe tummy pain, feeling or being sick, a high temperature or you may have diarrhoea
  • seizures (fits)
  • high levels of chemicals in your blood due to the breakdown of tumour cells (tumour lysis syndrome) - you have regular blood tests to check for this
  • kidney problems – you have regular blood tests to check this
  • a high level of acid in the body – it can cause changes to your breathing, feeling or being sick, headache and confusion. You have regular bloods to check this.
  • high levels of an enzyme found in the liver or bone. You have regular blood tests to check this.
  • a brain infection that can cause problems with thinking, strength, eyesight, balance, movement, and weakness on one side of the body. These changes get worse over days or weeks. Let your team know straight away.
  • blood clots that are life threatening; signs are pain, swelling and redness where the clot is. Feeling breathless can be a sign of a blood clot on the lung. Other rarer signs include problems speaking or moving parts of the body. Contact your advice line.
  • stomach ulcer - you might feel a burning sensation or pain in the middle of your tummy. Other symptoms might include bloating, burping, feeling full, feeling or being sick and pain.

Other side effects

There isn't enough information to work out how often these side effects might happen. You might have one or more of these. They include:

  • an autoimmune disease Open a glossary item that causes an overactive thyroid Open a glossary item. Symptoms include weight loss, a fast or irregular heartbeat, anxiety, difficulty sleeping, itchiness, finding it difficult to sit still and feeling tired all the time
  • inflammation of your thyroid gland (autoimmune thyroiditis) - symptoms include tiredness, weight gain, hair loss, muscle aches, joint pains, difficulty in pooing and forgetfulness  
  • a serious condition called Guillian-Barre syndrome. It affects the nerves throughout the body causing weakness, numbness, pins and needles and paralysis
  • an autoimmune disease called Goodpasture’s syndrome. It affects the lining of the lung and kidneys. Symptoms include feeling tired, a loss of appetite, not passing enough wee and coughing up blood

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do I need to know?

Other medicines, foods and drinks

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Pregnancy and contraception

This treatment may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for at least 6 months afterwards.

Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant while having treatment. 


Don’t breastfeed during treatment and for 4 months afterwards. The drug may come through in the breast milk.

Loss of fertility

It is not known whether this treatment affects fertility in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Treatment for other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.


Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having. Ask your doctor or pharmacist how long you should avoid live vaccinations.

In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and one of the shingles vaccines called Zostavax.

You can have:

  • other vaccines, but they might not give you as much protection as usual
  • the flu vaccine (as an injection)
  • the coronavirus (COVID-19) vaccine - talk to your doctor or pharmacist about the best time to have it in relation to your cancer treatment

Members of your household who are aged 5 years or over are also able to have the COVID-19 vaccine. This is to help lower your risk of getting COVID-19 while having cancer treatment and until your immune system Open a glossary item recovers from treatment.

Contact with others who have had immunisations - You can be in contact with other people who have had live vaccines as injections. Avoid close contact with people who have recently had live vaccines taken by mouth (oral vaccines) such as the oral typhoid vaccine. Sometimes people who have had the live shingles vaccine can get a shingles type rash. If this happens they should keep the area covered.

If your immune system is severely weakened, you should avoid contact with children who have had the flu vaccine as a nasal spray as this is a live vaccine. This is for 2 weeks following their vaccination.

Babies have the live rotavirus vaccine. The virus is in the baby’s poo for about 2 weeks and could make you ill if your immunity is low. Get someone else to change their nappies during this time if you can. If this isn't possible, wash your hands well after changing their nappy.

More information about this treatment

For further information about this treatment go to the Medicines Health and Regulatory Authority (MHRA).

You can report any side effect you have to the MHRA as part of their Yellow Card Scheme.

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