Cladribine (Leustat, Litak) | Cancer Research UK
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Cladribine (Leustat, Litak)

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This page tells you about the chemotherapy drug cladribine and its possible side effects. Cladribine is also called Leustat or Litak. There is information about


What cladribine is

Cladribine is a chemotherapy drug used mainly to treat hairy cell leukaemia and occasionally other types of leukaemia and lymphoma.


How cladribine works

Cladribine is one of a group of chemotherapy drugs known as anti metabolites. These stop cells making and repairing DNA. Cancer cells need to make and repair DNA so that they can grow and multiply. Cladribine kills abnormal white blood cells.


How you have cladribine

There are 2 types of cladribine – Leustat and LITAK.


You have Leustat into your bloodstream (intravenously). You can have it through a thin, short tube (a cannula) put into a vein in your arm each time you have treatment. Or you may have it through a central line, a portacath, or a PICC line. These are long, plastic tubes that give the drugs directly into a large vein in your chest. You have the tube put in before or during your course of treatment and it stays in place as long as you need it.

For hairy cell leukaemia you usually have it as drip for 7 days. 

For chronic lymphocytic leukaemia you usually have it as a 2 hour drip for 5 days each month. You may have up to 6 of these courses. 

You can read our information about having cancer drugs.


You have LITAK as an injection just under the skin for 5 days. Your doctor or nurse will show you how to do this. You can also see our video about how to give an injection just under the skin

Your doctor may prescribe a medicine called allopurinol to lower blood levels of uric acid

If you inject a wrong dose by accident, tell your doctor straight away. If you accidentally forget a dose of LITAK, don't inject a double dose to make up for it but let your doctor know as soon as possible.


Tests during treatment

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


About side effects

We've listed the side effects associated with cladribine. You can use the links to find out more about each side effect. Where there is no link, please go to our information about cancer drug side effects or use the search box at the top of the page.

You may have a few side effects. They may be mild or more severe. A side effect may get better or worse through your course of treatment. Or more side effects may develop as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)

The side effects may be different if you are having cladribine with other medicines.

Tell your doctor, nurse or pharmacist straight away if any of the side effects get severe.


Common side effects

More than 10 in every 100 people have one or more of the side effects listed below.

  • An increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, a sore throat, pain passing urine, or you may feel cold and shivery. If you have a severe infection this can be life threatening. Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C
  • Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
  • Bruising more easily due to a drop in platelets – 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)
  • Tiredness and weakness (fatigue) during and after treatment – most people find their energy levels are back to normal within 6 months to a year. Some people also feel dizzy and if you have this you shouldn't operate machinery or drive
  • High temperatures (fever) occur in about 7 out of 10 patients. You may also feel weak and have aching muscles and joints but this lessens as the treatment continues
  • Headaches
  • A cough and changes in breathing
  • Feeling and being sick may begin a few hours after starting treatment and can last for a few days. It is usually possible to control this side effect with anti sickness injections and tablets. If you are still being sick, tell your doctor or nurse
  • Skin rashes, which may last a few days
  • Soreness, redness and swelling of the injection area can happen with LITAK
  • Sweating
  • Fluid build up in tissues (oedema)

Occasional side effects

Between 1 and 10 in every 100 people have one or more of the following side effects.

  • Difficulty sleeping
  • Loss of appetite
  • Anxiety
  • A faster heart rate
  • Low blood pressure
  • Changes in your heart muscle which are usually temporary but for a small number of people may be permanent. Your doctor will check your heart before and after your treatment
  • A sore mouth and tongue
  • Itching
  • Constipation – if you have constipation drink plenty of fluids. Let your doctor or nurse know if you have it for more than 3 days as they can give you laxatives to help
  • Diarrhoea – drink plenty of fluids and let your doctor or nurse know if it gets severe or lasts more than 3 days
  • Stomach pains and air in the stomach or bowels (wind)
  • Muscle pain, joint pain, and bone pain – taking mild painkillers can help
  • The risk of developing a second cancer increases about 2 years after starting treatment – your treatment team will monitor you for this
  • An allergic reaction with Leustat – let your doctor or nurse know straight away if you have a sudden rash, itching, a swollen face or lips, or breathlessness
  • Blood clots with Leustat – let your doctor or nurse know straight away if you have swelling, pain or redness in your legs
  • Liver changes that are mild and unlikely to cause symptoms – the liver will almost certainly go back to normal when treatment ends
  • Generalised pain in the body

Rare side effects

Fewer than 1 in 100 people have these.

  • A skin reaction at the drip site (with Leustat), causing swelling, pain and redness – tell your doctor or nurse straight away if you have this
  • Women may stop having periods (amenorrhoea) but this may only be temporary
  • Loss of fertility – you may not be able to become pregnant or father a child after this treatment. Talk to your doctor before starting treatment if you think you may want to have a baby in the future. Men may be able to store sperm before starting treatment
  • Lack of production of blood cells – you may need medicines to treat this
  • High uric acid levels in the blood due to the breakdown of tumour cells (tumour lysis syndrome). You may have a tablet called allopurinol to take. Drinking plenty of fluids helps to flush out the excess uric acid
  • Numbness and tingling of the skin
  • Confusion
  • Sore eyes
  • Serious nerve damage that can cause difficulty coordinating movements or partial or complete paralysis. For some people this may be permanent
  • Kidney changes that are mild and unlikely to cause symptoms – they will usually go back to normal when treatment finishes
  • An illness called Stevens Johnson syndrome (with Leustat) causing blistering of the skin, mouth, eyes and genitals. Let your doctor or nurse know straight away if you have this
  • Shingles
  • Severe weight loss

Important points to remember

Talk to your doctor, pharmacist or nurse about all your side effects so they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Other medicines

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and any over the counter remedies. Some drugs can react together.

Pregnancy and contraception

Cladribine could harm a baby developing in the womb. It is important to use effective contraception so that you don't become pregnant or father a child while having this treatment. Men should continue to use effective contraception for at least 6 months after the end of treatment. Talk to your doctor or nurse about contraception before treatment starts.


Don't breastfeed during this treatment or for 6 months afterwards because the drug may come through in the breast milk.

Sodium and cladribine

If you need to control salt (sodium) in your diet it is important to be aware that cladribine and the fluid used to dilute it contain sodium. Tell your doctor if you are on a low salt diet.


Immunisations and chemotherapy

You shouldn't have immunisations with live vaccines while you are having chemotherapy or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your chemotherapy. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines), but not many people in the UK have these now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.


Related information


More information on cladribine

This page does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at

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Updated: 16 December 2015