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

Take this medication by mouth 1 hour before or 1 hour after a meal as directed by your doctor, usually once daily. It is important that you do not take this medication more than once daily.

The dosage is based on your medical condition, response to treatment, 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).

Do not increase your dose or take this medication more often than prescribed. Your condition will not improve any faster, and the risk of serious side effects may be increased.

Avoid eating grapefruit or drinking grapefruit juice while using this medication unless your doctor or pharmacist says you may do so safely. Grapefruit can increase the chance of side effects with this medicine. Ask your doctor or pharmacist for more details.

Since this drug can be absorbed through the skin and lungs, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the tablets.

Follow your doctor's instructions on how to correctly take capecitabine or letrozole with lapatinib.