Cancer drugs A to Z list
Cladribine is a chemotherapy drug. You pronounce it as klad-rih-been.
Cladribine is a treatment for:
hairy cell leukaemia
B cell chronic lymphocytic leukaemia (CLL)
Find out more about hairy cell leukaemia and CLL
Cladribine is a type of chemotherapy called an anti metabolite. It stops cells making and repairing . Cancer cells need to make and repair DNA so that they can grow and multiply.
How you have cladribine depends on the type of cancer you have. You can have it as an injection:
into your bloodstream (intravenously)
under the skin (subcutaneously)
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
You might have treatment through a thin short tube (a cannula) that goes into a vein in your arm. You have a new cannula each time you have treatment.
You usually have injections under the skin (subcutaneous injection) into the stomach, thigh or top of your arm.
You might have stinging or a dull ache for a short time after this type of injection, but they don't usually hurt much. The skin in the area may go red and itchy for a while.
The video below shows you how to inject just under your skin (subcutaneously).
You have cladribine as cycles of treatment. This means that you have the drug and then a rest to allow your body to recover.
Each cycle usually takes 28 days (4 weeks). How many cycles you have will depend on your type of leukaemia and situation.
Some people may need 1 course of treatment. Other people may have up to 6 cycles. The team looking after you will tell you more about how you will have it.
The following is an example:
once a day for 5 days as an injection under your skin (subcutaneously)
once a day for 5 days as a drip into your bloodstream (intravenously)
over 7 days as a continuous drip through a vein. You may have to stay in hospital for this
Your doctor may prescribe a medicine called allopurinol to lower blood levels of uric acid which can build up in your blood when the leukaemia cells are killed.
You have blood tests before and during your treatment. They check your levels of and other substances in the blood. They also check how well your liver and kidneys are working.
Before treatment starts you may have a blood test to check for viruses such as hepatitis B, hepatitis C, and HIV. This is called a viral screen.
It’s important for your doctor to know if you have had any of these viruses. This is because this treatment can weaken your and can cause the virus to become active again (reactivation).
Side effects can vary from person to person. They also depend on what other treatments you're having.
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.
We haven't listed all the side effects here. Talk to your healthcare team if you have any new symptoms that you think might be a side effect of your treatment.
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.
These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:
Increased risk of getting an infection is due to a drop in . Symptoms include a change in temperature, aching muscles, cough, headaches, feeling cold and shivery, pain or a burning feeling when peeing or generally feeling 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.
You might have medication to try and prevent some infections.
You might be breathless and look pale due to a drop in . This is called anaemia.
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. This is known as petechiae.
Tiredness and weakness (fatigue) can happen during and after treatment. Doing gentle exercises each day can keep your energy up. Don't push yourself, rest when you start to feel tired and ask others for help.
This treatment might make you feel dizzy. Don’t drive or operate machinery if you have this.
You might have a fever or feel shivery. Tell your healthcare team straight away if you get a high temperature.
Tell your healthcare team if you keep getting headaches. They can give you painkillers to help.
You might develop a cough or breathing problems. This could be due to infection, such as pneumonia or inflammation of the lungs (pneumonitis).
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 include a skin rash, dry skin and itching. This usually goes back to normal when your treatment finishes. Your healthcare team can tell you what products you can use on your skin to help.
Tell your nurse straight away if you have any pain, redness, swelling or leaking around your drip site.
If you have subcutaneous injection you might have pain, redness or swelling where the injection was given.
This drug might cause you to sweat more than usual. But there are ways to reduce sweating.
Let your healthcare team know if you are sweating much more than normal.
Contact your advice line if you have diarrhoea. For example, in one day you have 2 or more loose bowel movements than usual. If you have a , you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.
Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain . But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables.
Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.
is easier to sort out if you treat it early. Drink plenty and eat as much fresh fruit and vegetables as you can. Try to take gentle exercise, such as walking. Tell your healthcare team if you think you are constipated. They can give you a if needed.
You might have weak muscles or lack energy and strength in your muscles.
You might lose your appetite for various reasons while having cancer treatment. Sickness, taste changes or tiredness can put you off food and drinks.
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:
sepsis is a serious reaction to an infection - signs can include feeling very unwell, not passing urine, a very high or very low temperature, shivering, slurred speech or confusion, breathlessness, mottled or discoloured skin, extreme shivering or muscle pain. Call 999 or go to accident and emergency (A&E) immediately if you have any of these symptoms
allergic reaction that can cause a rash, shortness of breath, redness or swelling of the face and dizziness - some allergic reactions can be life threatening, alert your nurse or doctor if notice any of these symptoms
difficulty sleeping (insomnia)
nosebleeds
anxiety
changes to the heart such as a fast heart rate, murmur and damage to heart muscle (myocardial ischaemia)
low blood pressure
sore mouth
farting (flatulence) and stomach pain
a second cancer. Talk to your doctor if you are concerned about this
a blood disorder where your red blood cells get destroyed faster than they can be made (haemolytic anaemia)
changes to how the kidneys work including kidneys not working. This shows up in blood test results and goes back to normal when you finish treatment
changes to how the liver works. This shows up in blood test results and goes back to normal when you finish treatment
general pain including muscle pain, joint pain and bone pain
confusion
arthritis
swelling (oedema)
red, swollen, itchy or painful eyes (conjunctivitis)
These side effects happen in fewer than 1 in 100 people (less than 1%). You might have one or more of them. They include:
a severe skin reaction that may start as tender red patches which leads to peeling or blistering of the skin. You might also feel feverish and your eyes may be more sensitive to light. This is serious and could be life threatening
changes to the 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. You might have medication to help prevent this
nerve damage causing pins and needles, loss of ability to move your legs or other parts of the body
a
changes to the level of awareness (consciousness)
infections such as shingles can become active again if you've had it in the past
severe weight loss
inflammation of the voice box
inflammation of the blood vessels
We have more information about side effects and tips on how to cope with them.
Cancer drugs can interact with medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.
Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.
After having this treatment you should only have blood or platelets that are first treated with radiation (irradiated). The radiation lowers the risk of a reaction between your blood cells and the cells in the transfusion. No harm comes from the irradiated blood.
In your medical records there is a note saying you should only have irradiated blood. You have a card to carry with this information. This is in case you need treatment at another hospital.
This drug may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you are having treatment with this drug and for at least 6 months after treatment.
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.
You may not be able to become pregnant or get someone pregnant after treatment with this drug. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.
Men might be able to store sperm before starting treatment. And women might be able to store eggs or ovarian tissue. But these services are not available in every hospital, so you would need to ask your doctor about this.
Don’t breastfeed during this treatment and for 6 months afterwards. This treatment may come through in the breast milk.
If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.
Do not have live vaccines while you’re having treatment and for up to 12 months afterwards. For some people, it may be longer than this. The length of time you need to avoid live vaccines depends on the treatment you’ve had.
Ask your doctor or pharmacist how long you should avoid live vaccinations.
In the UK, live vaccines include rubella, mumps, measles, chickenpox, BCG, and yellow fever. You can usually have non-live vaccines. But they might not give you as much protection as usual. These include the:
flu vaccine, as an injection
coronavirus (COVID-19) vaccine
Talk to your doctor or pharmacist about the best time to have a vaccine in relation to your cancer treatment.
You can be in contact with other people who have had live vaccines as injections. If someone has had a live vaccine by mouth or nasal spray there may be a small risk the vaccine virus can be passed onto you if your is weakened.
Your healthcare team will let you know if you need to take any precautions if you are in close contact with someone who has had a live vaccine.
For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.
You can report any side effect you have to the Medicines and Healthcare products Regulatory Agency (MHRA) as part of their Yellow Card Scheme.
Last reviewed: 08 Sept 2026
Next review due: 08 Sept 2029
Hairy cell leukaemia (HCL) is a rare type of chronic leukaemia. It develops slowly from white blood cells called B lymphocytes. Find out about this type of leukaemia.
CLL affects the white blood cells called lymphocytes. It tends to develop very slowly. Find out about the treatment you might need and much more.
Chemotherapy is a standard treatment for some types of cancer. It uses anti cancer drugs to destroy cancer cells.
Coping with cancer can be difficult. There is help and support available. Find out about the emotional, physical and practical effects of cancer and how to manage them.
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