What side effects may I notice from receiving Lapatinib?

Side effects that you should report to your doctor or health care professional as soon as possible:

-allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
-breathing problems
-diarrhea
-redness, blistering, peeling or loosening of the skin, including inside the mouth
-signs and symptoms of a dangerous change in heartbeat or heart rhythm like chest pain; dizziness; fast or irregular heartbeat; palpitations; feeling faint or lightheaded, falls
-signs and symptoms of liver injury like dark yellow or brown urine; general ill feeling or flu-like symptoms; light-colored stools; loss of appetite; nausea; right upper belly pain; unusually weak or tired; yellowing of the eyes or skin
-swelling in your legs and feet
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

-cough
-decreased appetite
-mouth sores
-nausea, vomiting

This list may not describe all possible side effects for Lapatinib. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.