Gefitinib is used to treat lung cancer. It works by slowing or stopping the growth of cancer cells. Gefitinib blocks a certain protein (an enzyme called tyrosine kinase).

Read the Patient Information Leaflet if available from your pharmacist before you start taking gefitinib and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take gefitinib by mouth with or without food as directed by your doctor, usually once daily.

If you have trouble swallowing the tablet, you may place the tablet in a glass of water (4 to 8 ounces/120 to 240 milliliters). Stir well for 15 minutes. Drink all of the mixture right away. Rinse the cup with another 4 to 8 ounces (120 to 240 milliliters) of water and drink the rinse water to make sure you get the full dose.

Medications which reduce or block stomach acid (such as proton pump inhibitors/PPIs, H2 blockers, antacids) may reduce the absorption of gefitinib, making it work less well. If you take PPIs (such as omeprazole, lansoprazole), take gefitinib at least 12 hours before or 12 after the PPI. If you take antacids or H2 blockers (such as famotidine, ranitidine), take them at least 6 hours before or at least 6 hours after this medication.

The dosage is based on your medical condition, response to treatment, lab tests, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.

Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of side effects will increase.

See also Warning section.

Diarrhea, rash, acne, dry skin, nausea, vomiting, loss of appetite, nail problems, hair loss, red/sore mouth or throat, or unusual weakness may occur. If any of these effects last or get worse, tell your doctor or pharmacist right away.

Diarrhea is a common side effect. Drink plenty of fluids as directed by your doctor to reduce your risk of dehydration. Your doctor may prescribe anti-diarrhea medication to control your symptoms. Tell your doctor right away if you develop diarrhea that is severe or doesn't stop, or signs of dehydration (such as extreme thirst, dizziness, decreased urination).

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• signs of kidney problems (such as change in the amount of urine)
• unusual bleeding (coughing up blood, blood in urine)
• eye irritation/pain
• swelling of the ankles/feet

Gefitinib may cause rare (possibly fatal) lung disease (interstitial lung disease-ILD). Tell your doctor right away if you develop shortness of breath, cough, or fever.

Gefitinib can commonly cause a rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe reaction. Get medical help right away if you develop any rash.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• lung disease (such as pulmonary fibrosis)
• severe kidney disease
• eye problems
• stomach/intestinal ulcers
• other stomach/intestinal problems (such as diverticulitis, blockage, bowel disease)
• smoking
• cancer that has spread to the bowels

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using gefitinib. Gefitinib may harm an unborn baby. Ask about reliable forms of birth control while using this medication and for 2 weeks after the last dose. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if gefitinib passes into breast milk. Because of possible risk to the infant, breastfeeding is not recommended while using this medication. Consult your doctor before breastfeeding.

See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are:

• "blood thinners" (warfarin)
• drugs which reduce stomach acid (such as ranitidine, cimetidine, famotidine, omeprazole, lansoprazole, rabeprazole)
• vinorelbine
• NSAIDs (such as ibuprofen, naproxen)
• corticosteroids (such as prednisone)

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: diarrhea that is severe or doesn't stop, severe skin rash.

Do not share this medication with others.

Lab and/or medical tests (such as kidney/liver function) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If it is less than 12 hours before the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.