Gefitinib is used to treat locally advanced or metastatic non-small cell lung cancer, particularly in patients with mutations in EGFR exons 19 and 21. It is named after the “IRESSA250” printed on one side of the film-coated tablet. The recommended dose is 250 mg orally once daily, recommended on an empty stomach or at least two hours after a meal. Adverse reactions mainly include skin reactions, including rash, acne, dry skin, itching, etc. There are also adverse reactions of diarrhea to varying degrees, which can be treated symptomatically and can be reduced or discontinued in severe cases.