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Gefitinib (Iressa)

This page tells you about the biological therapy drug gefitinib and its possible side effects. There are sections about


What gefitinib is

Gefitinib is pronounced jeh-fit-ih-nib. It is also known by its brand name Iressa. It is a type of biological therapy called a tyrosine kinase inhibitor (TKI). Tyrosine kinase is a protein that plays a part in triggering the growth of cancer cells. Gefitinib blocks tyrosine kinase from sending growth signals.

It is a treatment for non small cell lung cancer that has spread into surrounding tissues (locally advanced cancer) or to other parts of the body. In order for gefitinib to work, the cancer cells need to have receptors for a protein called epidermal growth factor (EGFR). 

You may also have gefitinib as part of clinical trials for other types of cancer.


How you have gefitinib

Gefitinib is a tablet. You take it with a glass of water. If you can’t swallow tablets you can put it in half a glass of water and leave it to dissolve. This usually takes about 20 minutes and you will need to swill it round a bit. It is important to make sure that you drink all of the liquid.

You have gefitinib once a day and need to take it at about the same time each day. Avoid taking anti acid medicines 2 hours before taking gefitinib and for 1 hour afterwards. 

You usually carry on taking gefitinib for as long as it works. 

It is very important that you take tablets according to the instructions your doctor or pharmacist gave you. Whether you have a full or empty stomach, for example, can affect how much of a drug gets into your bloodstream. You should take the right dose, not more or less. 

If you take too many tablets by accident, let your doctor or pharmacist know straight away. If you forget to take a tablet and it is 12 hours or more before the next dose, take the missed tablet as soon as you remember. If it is less than 12 hours until the next dose, skip the next tablet and then take the next tablet at the usual time. Do not take a double dose to make up for the forgotten dose.

The side effects gefitinib may cause are listed below. Remember that you may only have 1 or 2 or a few of them. For some people they are mild but for others they may be more severe.


Common side effects

More than 10 in every 100 people have one or more of these.

  • Skin changes – up to 3 out of 4 people (75%) have a rash or red, dry, itchy skin or acne. Rarely, this may be severe and you may need to stop treatment for a while
  • Diarrhoea affects 1 out of 2 people (50%) – drink plenty of fluid and tell your doctor or nurse if it becomes severe, or continues for more than 3 days
  • Feeling weak, and lacking in energy and strength
  • Feeling or being sick happens in about 1 out of every 10 people (10%) but is usually well controlled with anti sickness drugs
  • Loss of appetite happens in about 1 out of 10 people (10%)
  • A sore mouth occurs in about 1 out of 10 people (10%)
  • Liver changes that are very mild and unlikely to cause symptoms may occur – the liver will almost certainly go back to normal when treatment is finished, but you will have regular blood tests to check how well your liver is working
  • Loss of fertility – we don’t know exactly how this drug may affect fertility. Talk to your doctor before starting treatment if you plan to have a baby in the future

Occasional side effects

Between 1 and 10 in every 100 people have one or more of these.

  • Increased risk of bleeding – this includes nosebleeds and bleeding from your gums. If you notice blood in your urine, stool, or in your vomit, contact your doctor or nurse straight away
  • Eye problems including blurred vision, sore, red, itchy, dry eyes (conjunctivitis) or infection – eye drops can help
  • Red and sore eyelids
  • Brittle or loose nails
  • Hair thinning
  • Kidney changes that are mild and unlikely to cause symptoms may occur – these will almost certainly go back to normal when treatment is finished, but you will have regular blood tests to check how well your kidneys are working
  • A high temperature (fever)
  • Severe lung problems occur in 1 in 100 people (1%) – if you have a cough, high temperature and are short of breath contact your treatment centre urgently
  • Inflammation of the bladder lining (cystitis) causing a burning feeling when you pass urine or making you need to pass urine often – let your doctor or nurse know if you have this

Rare side effects

Fewer than 1 in 100 people have these effects so they are rare but can be serious.

  • Abnormal eyelash growth or eye pain – if this is severe your doctors may reduce the dose or stop treatment
  • Inflammation of the pancreas causing severe pain in the upper part of the abdomen and severe nausea and vomiting
  • Inflammation of the liver, which makes you feel very ill – you may also have yellowing of the skin and eyes (jaundice). See your doctor or nurse straight away if you have this
  • A hole in the wall of the stomach or bowel – let your doctor or nurse know straight away if you have sudden, severe pain or blood in your vomit or stool

Important points to remember

You will not get all the side effects mentioned above. A side effect may get worse through your course of treatment. Or you may have more side effects as the course goes on. This depends on

  • How many times you've had a drug before
  • Your general health
  • How much of the drug you have (the dose)
  • Other drugs you are having

Coping with side effects

Talk to your doctor, pharmacist or nurse about all your side effects so they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Other medicines and remedies

Tell your doctor, nurse or pharmacist about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies. Some drugs can react together.

Medicines that may react with gefitinib include

  • Some anti epilepsy drugs
  • Some anti tuberculosis medicines
  • Some anti fungal drugs
  • Some medicines used to help people sleep
  • St John's wort 
  • Some medicines for indigestion, heartburn or stomach ulcers
  • Some medicines that prevent blood clots


Gefitinib may harm a developing baby. It is not advisable to become pregnant or father a child during treatment. If there is any chance that you or your partner could become pregnant, you need to talk to your doctor or nurse about reliable contraception before starting treatment.


Breastfeeding is not advisable during this treatment because the drug may come through in the breast milk.

Sugar intolerance

Gefitinib tablets contain a type of sugar called lactose. Contact your doctor before taking this medicine if you have an intolerance to lactose.



You should not have immunisations with live vaccines while you are having treatment or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your treatment. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines), but not many people in the UK have these now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.


More information on gefitinib

This page does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at

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Updated: 20 September 2013