Gefitinib is used to treat lung cancer. It works by slowing or stopping the growth of cancer cells. Gefitinib blocks a certain protein (an enzyme called tyrosine kinase).
WARNINGS: Gefitinib has rarely caused very serious (possibly fatal) liver disease. Get medical help right away if you develop symptoms of liver disease, including stomach/abdominal pain, extreme fatigue, dark urine, yellowing eyes/skin.
Gefitinib has also rarely caused very serious (possibly fatal) holes in the wall of the stomach or intestines. Get medical help right away if you develop stomach/abdominal pain, black/bloody stools, or vomit that looks like coffee grounds.