Gefitinib is a targeted therapy drug. It is used to treat non-small cell lung cancer (NSCLC) that has spread.

What is gefitinib?

Gefitinib belongs to a group of targeted therapy drugs known as cancer growth inhibitors.

It is used to treat non-small cell lung cancer (NSCLC) that has started to spread to:

  • surrounding tissues (locally advanced)
  • other parts of the body (advanced or metastatic). 

Gefitinib is used to treat cancers that have an abnormal form of a protein called epidermal growth factor receptor (EGFR). Tests are done on the cancer cells to check the level of EGFR. These cells might be taken from a biopsy, or from previous surgery. The test tells your doctor whether gefitinib is likely to work for you. 

It is best to read this information with our general information about lung cancer

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

How gefitinib is given

Gefitinib comes in tablets, so you can take it at home. You usually take gefitinib for as long as it is controlling the cancer. 

During treatment you usually see a cancer doctor, a cancer nurse or specialist nurse, and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

The nurse or pharmacist will give you the tablets to take home. Always take your tablets exactly as your nurse or pharmacist explains. This is important to make sure they work as well as possible for you. Do not stop taking your tablets unless your doctor tells you to. 

Your nurse or pharmacist may also give you anti-sickness drugs and other medicines to take at home. Take all your drugs exactly as they have been explained to you.

Before and during treatment, a nurse or person trained to take blood (phlebotomist) will take a blood sample from you. This is to check the level of your blood cells and to check how well your liver and kidneys are working.

Taking gefitinib tablets

You usually take gefitinib as a tablet once a day. Take it at about the same time each day. Swallow it whole with a glass of water. You can take it with or without food.

If you have trouble swallowing tablets, put the tablet in half a glass of water and leave it to dissolve. Do not crush gefitinib tablets and do not use any other type of liquid to dissolve them. It may take 20 minutes for a tablet to completely dissolve. Once it has dissolved, drink it straight away. Then refill the glass with water and drink it to make sure you have taken all the gefitinib.

If you forget to take the tablets, take the missed dose as soon as you remember. But if there is less than 12 hours until your next dose, do not take the missed dose. Never take a double dose.

Antacids or medicines to reduce stomach acid such as ranitidine or Gaviscon®, can affect how gefitinib works. Do not take antacids 2 hours before or 1 hour after taking gefitinib.

During treatment with gefitinib, you should not use the herbal remedy St John’s wort. This is because it can make gefitinib less effective.

Other things to remember about your tablets:

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

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. 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

Skin changes

You may develop a rash and your skin may become red, dry or flaky. Some people also feel itchy. These side effects are usually mild but sometimes can be more severe. 

During this treatment, you should protect your skin from the sun as this can make rashes worse. Cover up and use a high-factor sun cream of SPF 30 or above. 

If you have any skin changes, speak to your doctor or nurse. They can advise you about creams or lotions and give you medicines to relieve itching. 

If you have more severe side effects, your doctor may stop giving you gefitinib for a few days to allow your skin to recover.


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.

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.

Sore or dry mouth and throat

This treatment may cause a sore or dry mouth and throat. You may also get mouth ulcers. This can make you more likely to get a mouth or throat infection. Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.

If your mouth or throat is sore or dry:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco, and foods that irritate your mouth.

Feeling sick

Your doctor will give you anti-sickness drugs to help prevent or control sickness during and after chemotherapy. Take the drugs exactly as your nurse or pharmacist tells you. It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluids often and eat small amounts regularly. It is important to drink enough fluids. If you continue to feel sick, or if you are sick (vomit) more than once in 24 hours, contact the hospital as soon as possible. They will give you advice. Your doctor or nurse may change the anti-sickness drug to one that works better for you.

Feeling tired

Feeling tired is a common side effect of this treatment. It is often worse towards the end of treatment and for some weeks after it has finished. 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 use machinery.

Effects on the liver

This treatment may affect how your liver works. This is usually mild. You will have blood tests to check how well your liver is working.

Less common side effects of gefitinib

Eye problems

This treatment can cause eye problems. These are usually mild but can sometimes become serious and may need treatment. Tell your doctor or nurse if your eyes: 

  • feel dry, sore or watery
  • get red and inflamed
  • are sensitive to light.

Some people find that their eyelashes grow longer and more curly than usual, but this is not common.

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.

Allergic reaction

Some people have an allergic reaction while having this treatment. Signs of a reaction can include:

  • feeling hot or flushed
  • a skin rash
  • itching
  • shivering
  • feeling dizzy
  • a headache
  • feeling breathless
  • swelling of your face or mouth
  • pain in your back, tummy or chest.

If you feel unwell or have any of these signs, tell a doctor or nurse straight away. Do not take any more of this treatment until you have spoken to them.

Hair and nail changes

You may notice that the hair on your head and body becomes finer, curlier or more brittle. Some people have hair thinning or hair loss. These changes are usually temporary and gradually improve after treatment has finished.

The nails on your hands or feet may become red, sore and brittle. Let your nurse or doctor know if this happens. Wearing gloves when using detergents or washing dishes can help protect your nails.

Bladder irritation

Your bladder may become irritated during your treatment. You may:

  • have a burning feeling when you pass urine (pee)
  • need to pee more often or more urgently
  • have blood in your pee.

If you have these symptoms, tell your nurse or doctor. Try to drink at least 2 litres (31/2 pints) of fluids each day.

Bleeding problems

If you have any unusual bleeding while taking gefitinib, let your doctor know. This could include nosebleeds, bleeding gums or blood in your urine.

Severe tummy pain

Rarely, gefitinib can cause a hole (perforation) in the small bowel or an inflamed pancreas. Tell your doctor straight away if you have severe pain in the tummy (abdomen). It is also very important to let them know if you:

  • are bleeding from the back passage (rectum)
  • have black stools
  • are vomiting up blood
  • have vomit that looks dark and grainy, like coffee grounds.

Other information

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: 


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.


This treatment contains lactose. If you have an intolerance to some sugars, talk to your doctor before you start this treatment.


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.

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 October 2022
Next review: 01 April 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

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