Gefitinib (Iressa®)

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

What is gefitinib (Iressa®)?

Gefitinib (Iressa®) 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 targeted therapies and the type of cancer you have.

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

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

You will be given gefitinib as an outpatient. You have it on its own or in combination with other cancer drugs.

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.

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 to have treatment.

You will see a doctor or nurse before you have treatment. They will ask you how you have been feeling. If your blood results are okay, the pharmacist will prepare your targeted therapy. Your nurse will tell you when your treatment is likely to be ready.

Your course of treatment

You are given gefitinib as tablets (orally). This means you can take it at home. You may have it on its own, or with other drugs.

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

You usually continue taking gefitinib for as long as it is still working.

Taking gefitinib tablets

You usually take gefitinib once a day. Take the tablets at about the same time each day. Swallow them whole with a glass of water. You can take them 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 the 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:

  • Wash your hands after taking them.
  • 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. 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

Skin changes

You may develop a rash and your skin may become dry or flaky. Some people also feel itchy. These side effects are usually mild but sometimes can be more severe. 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. Do not worry if you do not 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 and throat

This treatment may cause a sore 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:

  • 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 and throat.

Sucking ice chips may sometimes help relieve mouth or throat pain. But if you are having radiotherapy to the head or neck, do not suck on ice. It can cause damage.

Feeling sick

Your doctor will give you anti-sickness drugs to help prevent or control sickness during your treatment. 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 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

Treatment with gefitinib may cause changes in how 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.

Less common side effects of gefitinib

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.

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 straight away.

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

Bladder irritation

Your bladder may become irritated during your treatment. You may notice a burning feeling when you pass urine (pee). Or you may need to go more often or more urgently. Tell your nurse or doctor if you have these symptoms. Try to drink at least 2 litres (3½ pints) of fluids each day. Rarely, you may pass blood in your urine. If you notice this, tell your doctor 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.

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. Contact 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 like coffee grounds.

Other information

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • throbbing pain, redness or swelling in a leg or arm
  • suddenly feeling breathless or coughing
  • sharp chest pain, which may be worse when you cough or take a deep breath.

If you have any of these symptoms, contact the hospital straight away on the 24-hour contact number you have been given. If you cannot get through to your doctor, call the NHS urgent advice number on 111.

A blood clot is serious, but it can be treated with drugs that thin the blood (anticoagulants). Your doctor or nurse can give you more information.

You can help reduce the risk of developing a blood clot by:

  • staying active during treatment
  • drinking plenty of fluids, especially water.

You may be given anticoagulants to help prevent a clot.

Other medicines

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

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.

Some other 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 taking gefitinib.

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


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