Gefitinib (Iressa)
Gefitinib is pronounced jeh-fit-ih-nib. It is also known as Iressa.
Gefitinib is a treatment for non small cell lung cancer (NSCLC) that has spread into the surrounding tissues (locally advanced) or to other parts of the body.
How does gefitinib work?
Gefitinib is a type of 
called a tyrosine kinase inhibitor (TKI). are proteins that sends signals telling cancer cells to grow. Gefitinib blocks these signals.
For gefitinib to work the cancer cells need to have receptors for a protein called (EGFR). Your doctor will test the cancer cells for this.
How do you have gefitinib?
Gefitinib is a tablet. You swallow it whole with a glass of water. You can take it with or without food
If you have difficulty swallowing tablets, you can dissolve gefitinib in half a glass of still water. Don’t use any other type of liquid.
Drop the tablet into the half glass of water without crushing it. Stir it occasionally for up to 20 minutes until the tablet has broken up into very small particles. Drink it straight away. Fill the glass to half way again with water and drink it to make sure you take the whole dose.
Taking your tablets
You should take the right dose, not more or less.
Talk to your healthcare team before you stop taking a cancer drug, or if you miss a dose.
How often do you have gefitinib?
You take gefitinib once a day. You usually carry on taking it for as long as it is still working unless the side effects get too bad.
Tests
You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.
What are the side effects of gefitinib?
Side effects can vary from person to person. They also depend on what other treatment you are having.
When to contact your team
Your doctor, nurse, or pharmacist will go through the possible side effects. They will monitor you closely during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:
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you have severe side effects
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your side effects aren’t getting any better
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your side effects are getting worse
Early treatment can help manage side effects better.
We haven't listed all the side effects here. Talk to your healthcare team if you have any new symptoms that you think might be a side effect of your treatment.
Remember it is very unlikely that you will have all of these side effects, but you might have some of them at the same time.
Common side effects
These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:
Skin changes
Skin problems include a skin rash, dry skin and itching. This usually goes back to normal when your treatment finishes. Your healthcare team can tell you what products you can use on your skin to help.
You should avoid going out in strong sunlight and use SPF 30+ sun cream when you do go out.
Diarrhoea
Contact your advice line if you have diarrhoea. For example, in one day you have 2 or more loose bowel movements than usual. If you have a , you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.
Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain fibre. But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables.
Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.
Feeling or being sick
Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.
It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.
Sore mouth and ulcers
Mouth sores and ulcers can be painful. It helps to keep your mouth and teeth clean, drink plenty of fluids and avoid acidic foods such as lemons. Chewing gum can help to keep your mouth moist. Tell your doctor or nurse if you have ulcers.
Loss of appetite
You might lose your appetite for various reasons while having cancer treatment. Sickness, taste changes or tiredness can put you off food and drinks.
Liver changes
You might have liver changes that are usually mild and unlikely to cause symptoms. They usually go back to normal when treatment finishes. You have regular blood tests to check for any changes in the way your liver is working.
Tiredness and feeling weak (fatigue)
You might feel very tired and as though you lack energy.
Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.
Occasional side effects
These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:
- an increased risk of bleeding such as a nose bleed or blood in the urine
- dry, brittle or loose nails during treatment. The skin around the nails and the nail beds might get infected causing swelling and redness.
- inflammation of the bladder causing pain when passing urine and need to pass urine often
- kidney problems that don't usually cause any symptoms
- high temperature - fever
- eye problems such as red, itchy, sore dry eyes or blurred vision
- sore, red eyelids or ingrown eyelashes
- thinning of your hair
- lung problems causing shortness of breath and coughing
- not enough water in your body (dehydration) caused by diarrhoea, being sick or loss of appetite
- an allergic reaction causing itching, rash or swelling tell your doctor if this happens
- protein in your urine (proteinuria)
Rare side effects
This side effects happens in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:
- inflammation of the pancreas - symptoms might include severe tummy pain, feeling or being sick, a high temperature or you may have loose poo
- a hole in the stomach or bowel
- inflammation of the liver
- a severe skin reaction that may start as tender red patches which leads to peeling or blistering of the skin. You might also feel feverish and your eyes may be more sensitive to light. This is serious and could be life threatening
- inflammation of your blood vessels in the skin – symptoms can vary depending on which blood vessels are affected - general symptoms include feeling very tired, loss of appetite, weight loss, a high temperature, and aches and pains
Coping with side effects
We have more information about side effects and tips on how to cope with them.
What else do I need to know
Other medicines, food and drink
Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.
Do not take this drug at the same time as antacids and similar drugs. Your doctor or pharmacist will give advice about this.
Lactose intolerance
This drug contains lactose (milk sugar). If you have intolerance to lactose, contact your doctor before taking this medicine.
Breastfeeding
Don’t breastfeed during this treatment because the drug may come through into your breast milk.
Pregnancy and contraception
This treatment might harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for a few months afterwards.
Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant while having treatment.
Loss of fertility
You may not be able to become pregnant or get someone pregnant after treatment with this drug. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.
Men might be able to store sperm before starting treatment. And women might be able to store eggs or ovarian tissue. But these services are not available in every hospital, so you would need to ask your doctor about this.
Treatment for other conditions
If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.
Immunisations
Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having. Ask your doctor or pharmacist how long you should avoid live vaccinations.
In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and one of the shingles vaccines called Zostavax.
You can have:
- other vaccines, but they might not give you as much protection as usual
- the flu vaccine (as an injection)
- the coronavirus (COVID-19) vaccine - talk to your doctor or pharmacist about the best time to have it in relation to your cancer treatment
Members of your household who are aged 5 years or over are also able to have the COVID-19 vaccine. This is to help lower your risk of getting COVID-19 while having cancer treatment and until your recovers from treatment.
Contact with others who have had immunisations - You can be in contact with other people who have had live vaccines as injections. Avoid close contact with people who have recently had live vaccines taken by mouth (oral vaccines) such as the oral typhoid vaccine. Sometimes people who have had the live shingles vaccine can get a shingles type rash. If this happens they should keep the area covered.
If your immune system is severely weakened, you should avoid contact with children who have had the flu vaccine as a nasal spray as this is a live vaccine. This is for 2 weeks following their vaccination.
Babies have the live rotavirus vaccine. The virus is in the baby’s poo for about 2 weeks and could make you ill if your immunity is low. Get someone else to change their nappies during this time if you can. If this isn't possible, wash your hands well after changing their nappy.
More information about this treatment
For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.
You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.
