Dacomitinib is used to treat a certain type of lung cancer (non-small cell lung cancer). It works by slowing or stopping the growth of cancer cells.

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

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

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

If you vomit up a dose, do not take another dose then. Take your next dose at the regular time.

The dosage is based on your medical condition and response to treatment. 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 serious side effects will increase.

Avoid certain drugs that reduce stomach acid/heartburn (proton pump inhibitors-PPIs such as lansoprazole, omeprazole) during treatment with dacomitinib. You may take antacids if needed during treatment with this medication. If you are also taking certain other drugs that reduce stomach acid/heartburn (H2 blockers such as famotidine, ranitidine), take dacomitinib at least 6 hours before or 10 hours after taking an H2 blocker.

Mouth sores, decreased appetite, weight loss, swelling/infection around your nails, or dry skin may occur. Use a moisturizer for dry skin as soon as you start treatment with this medication. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Temporary hair loss may occur. Normal hair growth should return after treatment has ended.

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.

Diarrhea is a common side effect. Drink plenty of fluids as directed by your doctor to lessen your risk of dehydration. Your doctor may prescribe anti-diarrhea medication (such as loperamide) to control your symptoms. Tell your doctor right away if you have:

• diarrhea that doesn't stop or is severe
• signs of dehydration (such as unusual decreased urination, unusual dry mouth/thirst, fast heartbeat, dizziness/lightheadedness)

Get medical help right away if you have any very serious side effects, including:

• signs of a new/worsening lung problem (such as shortness of breath, cough, fever)

Dacomitinib 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 dacomitinib, 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.

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.

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 dacomitinib. Dacomitinib may harm an unborn baby. Your doctor should order a pregnancy test before you start this medication. Ask about reliable forms of birth control while using this medication and for at least 17 days 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 this medication passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this medication and for at least 17 days after the last dose. 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:

• certain drugs that reduce stomach acid/heartburn (proton pump inhibitors-PPIs such as lansoprazole, omeprazole)

This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include dextromethorphan, pimozide, thioridazine, among others.

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.

Do not share this medication with others.

Lab and/or medical tests may be done while you are taking this medication. Keep all medical and lab appointments.

If you miss a 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.