Krypton Gefitinib 250mg Tablet is used in the treatment of non-small cell lung cancer. It is used in patients in which it has spread to other parts of the body, who have abnormal epidermal growth factor receptor (EGFR) genes, and who have not had previous treatment for cancer. Krypton Gefitinib 250mg Tablet can be taken with or without food, but better to have it same time every day for better results. You should continue to take it as long as your doctor advises for it. The duration of treatment varies according to your need and response to treatment. You should take it exactly as your doctor has advised. Taking it in the wrong way or taking too much can cause very serious side effects. It may take several weeks or months for you to see or feel the benefits but do not stop taking it unless your doctor tells you to. The most common side effects of this medicine include nausea, rash, vomiting and weight loss. It may cause severe diarrhea, drink plenty of fluids or consult with your doctor if it bothers you. It makes you sensitive towards sunlight, hence wear protective clothing or use sunscreen while going out. In case you develop ulceration in mouth, changes in your vision, or breathing difficulties than it is better to inform the doctor. Your doctor may advise for regular monitoring of liver function while you are taking this medicine. Many other medicines can affect, or be affected by, this medicine so let your healthcare team know all medications you are using. This medicine is not recommended during pregnancy or while breastfeeding. The use of effective contraception by both males and females during treatment is important to avoid pregnancy. If you have to take an antacid or any other medicine, take it at a gap of at least 2 hours after taking the cancer medicine.