Xalkori is a prescription medicine that is used to treat people with non-small cell lung cancer (NSCLC) that is advanced or that has spread to other parts of the body and is caused by a defect in a gene called ALK (anaplastic lymphoma kinase). Xalkori comes as a capsule to take by mouth. It is usually taken with or without food twice a day. Xalkori should be taken exactly as directed. Some common side effects of Xalkori include nausea, diarrhea, vomiting, swelling of your hands and feet and blurred vision.