Difficulty in breathing after taking Gefitinib may be a side effect of the drug, which needs to be stopped in time and relieved by oxygen. 1. Discontinue medication: If the dyspnea is caused by side effects of the drug, it will usually be relieved after stopping the drug, and the medication can be adjusted according to the situation. 2. Oxygen intake: Oxygen intake is an effective measure to relieve dyspnea when it occurs. Common adverse reactions of taking this drug are nausea, vomiting, diarrhea, rash, itching, fever, nosebleed and so on. Patients who are allergic to this product are prohibited, and this drug needs to be applied under the guidance of a physician’s interview. It is recommended that patients experiencing respiratory distress should seek medical attention without delay to avoid adverse outcomes.