How crizotinib works

Crizotinib, also known as Xalkori®, is a type of targeted therapy called a tyrosine kinase inhibitor (TKI), also known as a cancer growth inhibitor. Kinases are proteins in the body that regulate how cells grow and divide.

Crizotinib blocks (inhibits) the proteins from sending signals to the cancer to grow. This may help to stop or slow down the cancer.

Crizotinib is used to treat people who have non-small cell lung cancer (NSCLC) and who have a change to certain genes, called ALK or ROS1 genes. If you have this gene change, it is called ALK-positive or ROS positive. Before you start treatment, your doctor will test your cancer cells to see if you have either of these changes in your genes.

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

When crizotinib is given

Crizotinib is currently used to treat non-small cell lung cancer (NSCLC) that has spread to the surrounding tissues or to other parts of the body. Your cancer doctor can tell you if it might be helpful for you.

Crizotinib may only be available in some situations. Some people may be given it as part of a clinical trial. If a drug is not available on the NHS, there may be different ways that you can still have it. Your cancer doctor can give you advice about this. We have more information on what to do if a treatment is not available.

Taking crizotinib capsules

You take crizotinib as capsules twice a day, with or without food.

Take your capsules at the same time every day. You must swallow them whole, with a glass of water. You should not chew, open or crush them.

Do not eat grapefruit or drink grapefruit juice while you are prescribed crizotinib as it may increase side effects

Always take crizotinib exactly as your doctor, nurse or pharmacist has explained. This is important to make sure it works as well as possible for you.

There are some important things to remember when taking your capsules:

  • If you forget to take a capsule, you can take it when you remember, as long as it is more than 6 hours until your next dose. Do not take 2 doses at the same time to make up for the missed dose. Let you doctor or nurse know if you miss a dose.
  • If you are sick just after taking the capsule, contact the hospital. Do not take another dose.
  • Keep the capsules in the original packaging and at room temperature, away from heat and direct sunlight.
  • Keep the capsules in a safe place, out of the sight and reach of children.
  • Get a new prescription before you finish your last capsules and make sure you have plenty for holidays.
  • If your treatment is stopped, return any remaining capsules to the pharmacist. Do not flush them down the toilet or throw them away.

You usually continue to take crizotinib for as long it carries on working.

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.

Possible 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 called neutropenia.

If you have an infection, it is important to treat it as soon as possible. Contact the hospital straight away on the 24-hour contact number you have 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.

Symptoms of an infection include:

  • feeling shivery
  • a sore throat
  • a cough
  • diarrhoea
  • needing to pass urine often.

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

The number of white blood cells will usually return to normal before your next treatment. You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. 

Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin that may look like a rash.

Some people may need a drip to give them 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. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Vision changes

You may develop changes with your vision. This side effect is usually mild and will usually improve over time. Your eyes may take longer to adjust to change in the light or darkness of your surroundings. You may also have blurred vision. You may see flashing lights or dark spots called floaters.

If you wear glasses, or have any problems with your eyesight, it is important to have regular eye checks. You should also let your optician know that you are taking this treatment. Take care when driving as you may find other car headlights too bright. If you notice any changes to your eye sight, let your doctor or nurse know.

Diarrhoea or tummy pain

It is important to follow the advice your nurse or doctor gives you about diarrhoea. Contact the hospital if you have diarrhoea. They will give you advice on what to do and if you should see a doctor. They may give you anti-diarrhoea tablets to take at home.

If you have mild diarrhoea, it can usually be controlled with anti-diarrhoea tablets. Mild diarrhoea is when you have loose stool (poo) up to 4 times a day.

Try to drink at least 2 litres (3½ pints) of fluids every day.

It can help to avoid:

  • alcohol
  • caffeine
  • milk products
  • high-fat foods
  • high-fibre food.

Let the hospital know immediately if you have:

  • pain in your tummy (abdomen)
  • vomiting
  • blood or mucus in your poo
  • a fever.

You may need to go into hospital to have a drip (infusion) or other treatments. If your bowel is inflamed (colitis), you may need steroids.


This treatment can cause constipation. 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.

Feeling or being sick

Your doctor can give you anti-sickness drugs to prevent or reduce sickness or vomiting. Take the drugs exactly as your nurse or pharmacist tells you. If the sickness continues, tell your doctor. They can prescribe other anti-sickness drugs that may work better for you.

Build-up of fluid

You may put on weight or your ankles and legs may swell because of a build-up of fluid. Tell your doctor or nurse if this happens. Your doctor may need to change the amount of crizotinib you are having. If your ankles and legs swell, it can help to put your legs up on a foot stool or cushion. The swelling gets better after your treatment ends.

Loss of appetite

This treatment can affect your appetite. If you have a poor appetite, try to eat little amounts as often as possible. Keep snacks, such as nuts, grated cheese or dried fruit, handy to eat whenever you can.

It is important to try to eat well during your treatment. If you are having problems ask your nurse for advice and you can also ask to see a dietitian. You can add extra energy and protein to your diet with everyday foods or by using food supplements.


Some people feel very tired during their treatment. This is normal. If you feel more tired than usual it is important to pace yourself and get as much rest as you need. Try to balance this with taking some gentle exercise, such as short walks, which will help.

Effects on the liver

This treatment can affect how well your liver works. This can happen in the first few months of starting treatment. Your liver will return to normal when the treatment finishes.

You will have blood tests before you start the treatment and regularly while you are taking it, to check your liver is working properly. If blood tests show any changes, your doctor might stop your treatment until your blood tests return to normal. You may start the treatment again at a lower dose. If you drink alcohol, your doctor may suggest that you avoid alcohol or reduce the amount you drink.

Changes to your heartbeat and dizziness

Sometimes crizotinib can cause an irregular, or slow, pulse rate or heartbeat while you are taking it. This can cause dizziness. If you feel dizzy or faint, it is important to contact the hospital straight away. Avoid driving or operating machinery if you feel dizzy.

Your doctor may carry out regular heart tests such as an ECG (electrocardiogram) before starting treatment, and at points during and after your treatment.

Numb or tingling hands or feet (peripheral neuropathy)

This treatment affects 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. The symptoms usually improve slowly after treatment finishes, but for some people they may never go away. Talk to your doctor if you are worried about this.

Skin changes

This treatment may affect your skin. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day. This treatment can cause a rash, which may be itchy.

Always tell your doctor or nurse about any skin changes. They can give you advice and may give you creams or medicines to help. Any changes to your skin are usually temporary and improve when treatment finishes.

Effects on the lungs

Rarely, this treatment may cause inflammation in the lungs. Tell your doctor or nurse if you experience any unusual shortness of breath or trouble with breathing.

Other information about crizotinib

Other medicines

This treatment may interact with other medicines, including some that are used to treat epilepsy and some antibiotics. It may also interact with the herbal remedy St John’s wort.

Tell your doctor about any medicines you are taking, including over-the-counter drugs, complementary therapies and herbal drugs.


This treatment can affect whether you can get pregnant or father a child.

If you are worried about fertility, it is important to talk with your doctor before you start treatment. There may be ways to preserve fertility for men and women.


Your doctor will advise you not to become pregnant or father a child while having this treatment. The drugs may harm a developing baby. It is important to use effective contraception during, and for a few months after, treatment. You can talk to your doctor or nurse about this.


If you have sex during this course of treatment, you need to use a condom. This is to protect your partner in case there is any trace of the drug in semen or vaginal fluids.


Women are advised not to breastfeed while having this treatment. This is because the drugs could be passed to the baby through breast milk.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that 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.