Gefitinib (Iressa®)

Gefitinib is a targeted therapy drug used to treat non-small cell lung cancer (NSCLC). It is best to read this information with our general information about the type of cancer you have. Gefitinib is given as tablets. Your cancer doctor or nurse will tell you how often you will have it.

Like all targeted therapy drugs, gefitinib can cause side effects. Some of the side effects can be serious, so it’s important to read the detailed information below. How targeted therapy affects people varies from person to person. Your healthcare team can talk to you more about this and give you advice on how to manage any side effects.

Tell your doctor or nurse straight away if you: 

  • have a temperature
  • feel unwell
  • have severe side effects, including any we don’t mention here.

Rarely, side effects may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

If you need to seek medical attention for any reason, always tell the healthcare staff that you are having this treatment.

What is gefitinib?

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

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

How targeted therapies work

This animation shows how targeted therapies work and what effect they have on the body.

About our cancer information videos

How targeted therapies work

This animation shows how targeted therapies work and what effect they have on the body.

About our cancer information videos

How gefitinib works

Gefitinib is a type of drug called a tyrosine kinase inhibitor (TKI), which is also called a cancer growth inhibitor. Kinases are proteins in the body that control how the cells grow and divide. Gefitinib blocks (inhibits) the protein from sending signals to the cancer cells that make them grow and divide.

When gefitinib is given

Gefitinib only works for cancers that have an abnormal form of a protein called epidermal growth factor receptor (EGFR). Tests are done on a sample of cancer cells from your lung to check the level of EGFR. This tells your doctor whether gefitinib is likely to help you.

The National Institute for Health and Care Excellence (NICE) gives advice on which new drugs should be available on the NHS in England and Wales. The Scottish Medicines Consortium (SMC) gives advice on the use of new drugs within the NHS in Scotland. NICE and the SMC recommend gefitinib as a possible first treatment for people with NSCLC that is EGFR positive and has spread to surrounding tissues or other parts of the body (advanced or metastatic cancer).

If you live in Northern Ireland, your doctor can tell you if gefitinib is suitable for you. Some people may be given gefitinib as part of a clinical trial.

Taking gefitinib

You take gefitinib as a tablet once a day. Try to take it at about the same time each day. You can take the tablet with a glass of water, and with or without food.

If you have trouble swallowing tablets, put the tablet in a glass of water and leave it to dissolve. It may take 20 minutes 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.

Always take your tablets exactly as your nurse or pharmacist explained. This is important to make sure they work as well as possible for you.

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

  • If you are sick just after taking the tablets, tell your doctor. You may need to take another dose. Don't take another dose without telling your doctor first.
  • If you forget to take a tablet, take it as soon as you remember. But if there is less than 12 hours until your next dose, don’t take it. Just take your next dose at the usual time. Never take a double dose.
  • Don’t take antacids two hours before or one hour after taking gefitinib. They can affect how it works.
  • Keep tablets in the original package and at room temperature, away from heat and direct sunlight.
  • Keep the tablets safe and out of the reach of children.
  • Get a new prescription before you run out of tablets.
  • Make sure you have plenty of tablets for holidays.
  • If your treatment is stopped, return any tablets you do not use to the pharmacist.

Possible side effects

We have included the most common side effects of gefitinib. We have also included some less common and rarer side effects. You may get some of the side effects we mention, but you will not get them all.

If you are also taking other anti-cancer drugs, some side effects may be worse. You may also have side effects not listed here.

Your doctor can prescribe drugs to help control some side effects. It is very important to take them exactly as your nurse or pharmacist has explained.

Your nurse will give you advice about managing side effects. After your treatment is over, the side effects will start to improve. Always tell your doctor or nurse about the side effects you have.

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.

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 once treatment is over.

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.

Skin changes

You may develop an acne-like rash on the face, neck and body. The skin may also become dry, itchy and flaky.

Always tell your doctor or nurse about any skin changes or if they get any worse. They can give you advice and prescribe creams or medicines to help.

Here are some tips:

  • Wash with tepid water using mild, unperfumed, soap-free cleansers
  • Moisturise your skin regularly with unperfumed moisturisers – ask your doctor or nurse what’s best
  • Don’t use anti-acne products or any products containing alcohol on your skin
  • Wear sunscreen with sun protection factor (SPF) of at least 30 when in the sun, and cover up with clothing or a hat.

Rarely people may have a very severe skin reaction. You must contact the hospital straight away if this happens. The symptoms can include large blisters, peeling skin and sores in your mouth. You may also have a fever (high temperature).

If you have severe skin problems your doctor may lengthen the time in between your treatments or lower the dose.


If you have diarrhoea, contact the hospital for advice. 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 and high-fibre foods.

Loss of appetite

This treatment can affect your appetite. Don’t worry if you don’t eat much for a day or two. But if your appetite does not come back after a few days, tell your nurse or dietitian. They will give you advice. They may give you food or drink supplements.

Sore mouth

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

If your mouth is sore:

  • 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 can give you anti-sickness drugs to help prevent or control sickness. If you still feel sick, tell your doctor. They can prescribe other anti-sickness drugs that may work better for you.

Feeling tired

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.

Eye problems

Your eyes may become dry and feel sore, or get red and inflamed. Some people’s eyes may water and they may be sensitive to light. Your doctor can give you eye drops to help with these problems. If you get pain in your eyes or have changes in your vision, let your doctor know immediately.

Some people find that their eyelashes grow longer and more curly than usual, but this isn’t common.

Bladder irritation

Your bladder may feel irritated during your treatment. You may notice a burning feeling when you pass urine, or you may need to go more often or more urgently. Tell your nurse or doctor if you have these symptoms. Drink around two litres (three and a half pints) of fluids per day. Rarely, you may pass blood in your urine. If you notice this, tell your doctor straight away.

Effects on the liver

Treatment with gefitinib may cause changes in the way that your liver works. This will return to normal when treatment finishes. During treatment, your doctor will take regular blood samples to check your liver is working properly.

Watch our hair loss video playlist

In these videos, people with experience of cancer and hair loss share their stories. You can also watch tutorials on wigs, headwear and eye make up.

Watch our hair loss video playlist

In these videos, people with experience of cancer and hair loss share their stories. You can also watch tutorials on wigs, headwear and eye make up.

Less common side effects

Breathing problems

This is an uncommon side effect that may affect a small number of people taking gefitinib.

If you become breathless, your breathing worsens, or you have a cough or fever, tell your doctor straight away. It may mean you have an inflammation of the lungs, which can be serious.

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

Very rarely, gefitinib can cause a hole (perforation) in the small bowel or an inflamed pancreas. If you have severe pain in the tummy, and sickness and vomiting, contact your doctor immediately. It is also very important to let them know if you:

  • are bleeding from the back passage
  • have black stools
  • are vomiting up blood
  • have vomit that looks like coffee grounds.

Other information

Other drugs

Some medicines, including ones you buy in a shop or chemist, can be harmful while you are having this treatment. Tell your cancer doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies.


Your doctor will advise you not to get pregnant or father a child while having this treatment and for some time afterwards. The drugs may harm the developing baby. It is important to use effective contraception.


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


Doctors don’t yet know how this treatment may affect your fertility (the ability to become pregnant or father a child). If you are worried about this, talk to you doctor before treatment starts.

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 this treatment.