Imatinib is a targeted therapy. It is used to treat some types of leukaemia, blood disorders and gastro-intestinal stromal tumours called GISTs.

What is imatinib?

Imatinib is used to treat:

Imatinib may also be used to treat:

  • gastro-intestinal stromal tumours (GISTs), a rare cancer that affects the supporting tissue of the bowel or stomach
  • dermatofibrosarcoma protuberans (DFSP), a rare cancer that affects the tissue under the skin.

Your doctor can tell you if imatinib is suitable for you. Some people may be given this treatment as part of a clinical trial. It is best to read this with our information about the type of cancer you have. Imatinib is a type of targeted therapy drug called a cancer growth inhibitor. Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How is imatinib given

Imatinib comes as tablets or capsules. The nurse or pharmacist will give you them to take home. Always take them exactly as explained. This is important to make sure they work as well as possible for you.

During treatment you will see a haematologist (doctor who treats blood cancers) or a cancer doctor, a specialist nurse and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information. You keep taking imatinib for as long as your doctor tells you. Do not stop taking it without talking to your doctor.

Taking imatinib tablets or capsules

You usually take imatinib once or twice a day, depending on the dose your doctor prescribes. You should take it with a meal. The tablets or capsules must be swallowed whole with a glass of water. They should not be chewed, opened or crushed. Take them at the same time every day.

If you find it hard to swallow the tablets or capsules, tell your doctor, nurse or pharmacist. They may suggest that you dissolve them in still water or apple juice. They will give you clear instructions on how to do this.

If you forget to take imatinib, you should take the missed dose as soon as possible within the same day. If a full day has gone by, let your doctor or nurse know. Do not take a double dose unless your doctor tells you to.

Other things to remember about your tablets or capsules:

  • Keep them in the original package and at room temperature, away from heat.
  • Keep them safe and out of sight and reach of children.
  • If you are sick just after taking the capsules or tablets, contact the hospital. Do not take another dose.
  • If your treatment is stopped, return any unused imatinib to the pharmacist.

About 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 have not 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 visit the electronic Medicines Compendium (eMC) for more detailed information.

Common side effects

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is sometimes called neutropenia.

An infection can be very serious when the number of white blood cells is low. It is important to get any infection treated as soon as possible. Contact the hospital straight away on the 24-hour contact number you have been given if:

  • your temperature goes over 37.5°C (99.5°F)
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection
  • your temperature goes below 36°C (96.8°F).

Symptoms of an infection include:

  • feeling shivery and shaking
  • a sore throat
  • a cough
  • breathlessness
  • diarrhoea
  • needing to pass urine (pee) a lot, or discomfort when you pass urine.

It is important to follow any specific advice your cancer treatment team gives you.

You will have regular blood tests during treatment. If needed, your doctor may reduce or delay your treatment for a short time, until your cell count increases.

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 or purple spots on the skin that may look like a rash.

Tell your doctor if you have any unexplained bruising or bleeding. 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 have symptoms such as:

  • pale skin
  • lack of energy
  • feeling breathless
  • feeling dizzy and light-headed.

Tell your doctor or nurse if you have these symptoms.

If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Feeling sick

This is usually mild. Your doctor can prescribe anti-sickness (anti-emetic) drugs to prevent or reduce sickness and vomiting. Taking imatinib with food also helps. Tell your doctor if the sickness isn't controlled or if it continues. They can give you other anti-sickness drugs that may work better for you.


This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is usual for you, or having watery or loose stools. If you have a stoma, it will be more active than usual.

If you have diarrhoea:

  • try to drink at least 2 litres (3½ pints) of fluids each day
  • avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods
  • contact the hospital for advice.

Indigestion and wind

Some people have indigestion or wind when taking imatinib. They may also have acid reflux, which is when acid comes up from the stomach and into the gullet. If this happens, tell your doctor.


This treatment may cause headaches. If you have headaches, tell your doctor. They may give you painkillers to help.

Muscle and bone pain

This treatment can cause:

  • muscle pain or cramps
  • bone pain
  • swollen joints.

Tell your doctor if this happens. They can prescribe painkillers to help.

Build-up of fluid

You may gain weight or develop swelling around the eyes and ankles because of fluid build-up. Your doctor may prescribe drugs that make you pass more urine (diuretics) to help get rid of some fluid. But it often improves by itself.

If you put on weight very quickly it is important to let your doctor know straightaway.

Skin changes

Some people develop an itchy rash. If this happens, it is important to let your doctor know. They can advise you about creams or lotions to use, or prescribe medicines to relieve itching.

If you have a severe rash or any blistering or peeling contact your doctor immediately.

Your skin may be more sensitive to sun while taking imatinib. Use a sun cream with a sun protection factor (SPF) of at least 30 when you are in the sun. Cover up with clothing and a hat.

Less common side effects

Loss of appetite

If you lose your appetite try to eat smaller meals more often. If you find it difficult to eat enough, ask to speak to a nurse or dietitian. They can give you advice on getting more calories and protein in your diet. They may give you food supplement drinks to try. Your doctor can prescribe these and you can buy them from chemists.


This treatment can cause constipation. Constipation means that you are not able to pass stools (poo) as often as you normally do. It can become difficult or painful. Here are some tips that may help:

  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
  • Do regular gentle exercise, like going for short walks.

If you have constipation, contact the hospital for advice. Your doctor can give you drugs called laxatives to help.

Cough or breathlessness

You may feel breathless or develop a cough. Contact your doctor for advice if you develop these symptoms. If you have any difficulty breathing contact your doctor immediately.

Difficulty sleeping

If you are finding it difficult to sleep, tell your doctor.


Feeling tired is a common side effect. 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.

Effects on the eyes

Imatinib can cause eye pain, dry or watery eyes, or blurred vision. If your eyes are affected, tell your doctor. You should be careful when driving or operating machinery if your vision has changed.

Changes to your taste

You may get a bitter or metal taste in your mouth. Sucking sugar-free sweets may help with this. Some foods may taste different or have no taste. Try different foods to find out what tastes best to you. Taste changes usually get better after treatment finishes. Your nurse can give you more advice.

Feeling dizzy

You may feel dizzy. Tell your doctor if this happens.

Hair thinning

Your hair may get thinner while you are taking imatinib. Your nurse can talk to you about ways to cope with hair loss.

Effects on the liver and kidneys

Imatinib may cause changes in the way that your kidneys and liver work. Your doctor will take regular blood samples to check your liver and kidney are working properly.

Effects on the heart

Some people may notice a change to their heartbeat. Let your doctor know if this happens. Less commonly, imatinib may have other effects on the heart. Contact a doctor immediately if you:

  • have pain or a tightness in your chest
  • feel breathless or dizzy
  • feel your heart is beating too fast or too slowly.

Other conditions can cause these symptoms, but it is important to get them checked by a doctor.

Numbness or tingling in hands or feet

This treatment can cause numbness or tingling in the hands or feet. Tell your doctor if you notice any changes.

Other information about imatinib

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.

Hepatitis B reactivation

Tell your doctor if you have had hepatitis B (a liver infection) in the past. This treatment can make it active again. Your doctor or nurse will talk to you about this and may test you for it.


Vaccinations can reduce your risk of getting certain infections. Your doctor or nurse may talk to you about having vaccinations.

Doctors usually recommend that people with cancer have a flu vaccination and a coronavirus (covid) vaccination. These are both inactivated vaccinations that can help reduce the risk of infection. People with weak immune systems can have these, as they are not live vaccinations. 

If your immune system is weak, you need to avoid live vaccinations. This is because they can make you unwell. Live vaccines contain a very weak version of the illness they are vaccinating you against. Your cancer doctor or GP can tell you more about live and inactivated vaccinations.


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.


Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.


You are advised not to breastfeed while having this treatment, or for some time after treatment finishes. This is because the drugs could be passed to the baby through breast milk.

Your doctor or nurse can give you more information.

Lactose intolerance

Some brands of imatinib contain a small amount of lactose. If you have a lactose intolerance, talk to your doctor before you start taking this.

Medical treatment

If you need medical treatment for any other reason, always tell the doctors and nurses that you are having treatment with imatinib. Give them the contact details for your haematologist or 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 imatinib.