Imatinib

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 imatinib is 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.

Before or on the day of treatment, a nurse or person trained to take blood (phlebotomist) will take a blood sample from you. This is to check that your blood cells are at a safe level for you to have your treatment. 

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. If it is nearly time for your next dose, skip the missed dose and continue with your usual schedule and 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. You may have some rarer side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

 Your doctor, nurse or pharmacist can give you drugs to help control some side effects. It is important to take them exactly as they tell you. This means the drugs will be more likely to work for you. Your doctor, nurse or pharmacist will give you advice about managing your side effects.  Usually most side effects improve with time.

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.

Diarrhoea

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.

Headaches

This treatment may cause headaches. If you have headaches, tell your doctor. They may give you 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 tell your doctor. 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.  You should also tell them straight away if you feel any flu-like symptoms, for example, a high temperature or pain in your joints.

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.

Feeling tired (fatigue)

Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest between activities.

Being physically active can help to manage tiredness and give you more energy. It also:

  • helps you sleep better
  • reduces stress
  • improves your bone health.

If you feel sleepy, do not drive or operate machinery.

Less common side effects

Loss of appetite

This treatment can affect your appetite. Don't worry if you do not eat much for a day or 2. But if your appetite does not come back after a few days, or if you are losing weight, tell your nurse or dietitian. They can give you advice. They may give you food or drink supplements. Or they may suggest changes to your diet or eating habits to help.

Constipation

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 on the 24-hour number for advice. They can give you drugs called laxatives to help. 

If you have not been able to pass stools for over 2 days and are being sick, contact the 24-hour number straight away. 

Effects on the lungs

This treatment can cause changes to the lungs. Tell your doctor if you develop:

  • a cough
  • wheezing
  • breathlessness.

You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs.

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.

Difficulty sleeping

If you are finding it difficult to sleep, tell your doctor. They may be able to give you something to help.

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. Your nurse can give you more advice.

Dizziness

This treatment can cause dizziness. Tell your doctor or nurse if this happens. It is important that you do not drive or operate machinery if you feel dizzy.

Hair thinning

Your hair may become thinner when you are taking this treatment. This is usually mild. Ask your nurse for advice if you are worried about this.

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

This treatment can affect how the heart works. You may have tests to see 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 your doctor straight away on the 24-hour number the hospital has given you if you have any of these symptoms during or after treatment:
  • pain or tightness in your chest
  • breathlessness
  • dizziness
  • changes to your heartbeat.

Other conditions can cause these symptoms, but it is important to get them checked by a doctor. If you cannot get through to your doctor, call the NHS urgent advice number on 111.

Numb or tingling hands or feet (peripheral neuropathy)

This treatment may affect the nerves, which can cause numb, tingling or painful hands or feet. You may find it hard to fasten buttons or do other fiddly tasks.

Tell your doctor if you have these symptoms. They sometimes need to lower the dose of the drug. Talk to your doctor if you are worried about this.

Tumour lysis syndrome (TLS)

Rarely, this treatment may cause cancer cells to die and break down quickly. When cancer cells break down very quickly, it can cause a sudden release of large amounts of chemicals into the blood. This is called tumour lysis syndrome (TLS).

Your kidneys can usually keep these chemicals balanced. But they might not be able to cope with very large amounts. The chemical imbalance can affect how well your kidneys work and cause problems with your heart rhythm. 

You will have regular blood tests to check the levels of these chemicals. 

If you are at risk of TLS, your doctor can give you treatment to help prevent it. You may have:

  • extra fluids through a drip
  • medicines such as rasburicase or allopurinol.

Drinking at least 2 litres (3½ pints) of fluid a day will also help.

Other information about imatinib

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: 

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.

Hepatitis B reactivation

If you have had a liver infection called hepatitis B in the past, this treatment can make it active again. Your doctor or nurse will talk to you about this. They will test you for hepatitis B.

Vaccinations

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.

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.

Contraception

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.

Breastfeeding

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.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses you are having cancer treatment. Give them the contact details for your 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 cancer treatment.

About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert health professionals and people living with cancer.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 September 2022
|
Next review: 01 March 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.