This medication is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. It is used to treat locally advanced or metastatic non-small cell lung cancer in people who have activating mutations of EGFR tyrosine kinase (i.e., they have EGFR tyrosine kinase that responded to this medication).

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose is one 250 mg tablet once a day. Try to take it at the same time each day.

This medication may be taken with or without food.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose and there are 12 hours or more until your next dose, take it as soon as possible and continue with your regular schedule. If it is less than 12 hours until  your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Each reddish-brown, round, biconvex, coated tablet, engraved ";APO" over ";250" on one side and plain on the other, contains 250 mg of gefitinib. Nonmedicinal ingredients: amino methacrylate copolymer, colloidal silicon dioxide, crospovidone, ferric oxide red, magnesium stearate, polyethylene glycol, polyvinyl alcohol, talc, and titanium dioxide.

Gefitinib should not be taken by anyone who:

• is allergic to gefitinib or to any of the ingredients of the medication
• has an EGFR expression negative tumour

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• dry, red, itchy eyes
• fever
• red, sore eyelid
• severe or long-lasting diarrhea, vomiting, nausea, or loss of appetite
• signs of allergic reaction (e.g., skin rash, itching, redness)
• symptoms of bladder inflammation (e.g., burning sensation when passing urine, increased need to urinate, blood in the urine)
• ulcer on the surface of the eye (with or without ingrowing eyelashes)
• vision changes (e.g., blurred vision, eye pain, increased sensitivity of the eyes to light)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of a severe skin reaction (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)
• signs of bleeding (e.g., blood in urine, coughing blood, cuts that don't stop bleeding)
• signs of gastrointestinal perforation (i.e.., a hole through the stomach or bowel wall; symptoms include severe abdominal pain, nausea, vomiting, chills or fever)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• signs of severe breathing problems (e.g., chest pain, severe or worsening breathlessness with or without cough or fever)
• sudden severe headache

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Abnormal bleeding: The use of gefitinib may increase the risk of bleeding. If you have signs of unusual bleeding, such as passing black tarry stools, have bloody diarrhea, vomit or cough up blood, or have unusual bruising, contact your doctor right away. People with bleeding disorders should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether and special monitoring is needed. People taking blood thinners such as warfarin should have regular blood tests to check how quickly their blood is clotting.

Dehydration: Gefitinib commonly causes diarrhea, nausea, and vomiting, which can contribute to dehydration and additional ill effects. If you experience severe diarrhea or diarrhea and vomiting for several days in a row, contact your doctor as soon as possible.

Gastrointestinal perforation: Rarely, gefitinib can cause perforation (holes) in the stomach or intestines. If you experience severe abdominal pain, fever, vomiting, or black and tarry stools, contact your doctor immediately.

Grapefruit juice: Grapefruit juice prevents this medication from leaving the body as it should, causing the medication to build up in the body and result in side effects. People should not drink grapefruit juice while taking this medication.

Interstitial lung disease (ILD): This is a rare but serious complication. People who are over 55, those with other lung or heart conditions, and people who smoke have an increased risk of death from ILD. This medication should be stopped if ILD develops. Contact your doctor if you develop symptoms of ILD, such as shortness of breath, cough, and fever.

Kidney function: Gefitinib may cause kidney damage or decreased kidney function as a result of dehydration. People with reduced kidney function or kidney disease should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Gefitinib may cause liver damage or decreased liver function. People with reduced liver function or liver disease should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor will monitor your liver function with blood tests while you are taking gefitinib.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Weakness or impairment: This medication usually does not make you drowsy or impair your ability to drive or operate machinery. However, it may make some people feel weak. Do not drive or operate machinery if you feel weak.

Pregnancy: There are no adequate studies of use of gefitinib by pregnant women. This medication may cause harm to an unborn baby if it is taken during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if gefitinib passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children under 16 years of age.

There may be an interaction between gefitinib and any of the following:

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.