Erythroxa is the trade name and generic name of Gefitinib tablets, which can reach the peak blood concentration in about 3 to 7 hours after absorption by oral administration, thus exerting the therapeutic effect of the drug. Gefitinib is a selective inhibitor of surface growth factor receptor tyrosine kinase. After gefitinib tablets are administered orally, the peak blood concentration can be reached in about 3~7 hours, and the steady-state blood concentration can be reached after 7~10 consecutive days of administration, so as to achieve the promotion of apoptosis of tumor cells, inhibition of invasion and secretion of angiogenic factors, and enhancement of anti-tumor activity of other treatments. The use of the drug can cause adverse reactions such as diarrhea, rash, itching, dry skin and acne, known to have severe allergic reactions to the active substance or any of the excipients of the product. In the process of choosing Gefitinib for treatment, it is important to use the drug strictly in accordance with the doctor’s instructions.