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.