Causes of coughing after 1 month of chemotherapy for small cell lung cancer include adverse reaction of drugs, complication of lung infection, compression of lung tissues and airways by tumor cells and so on, which need to be treated causally. 1. Due to individual differences, chemotherapeutic drugs are not absolutely the most effective and safest, and the adverse reaction of coughing may occur in the process of using drugs. 2. If lung infection occurs in the course of chemotherapy, the stimulation of inflammation will also cause coughing symptoms. 3. If the tumor cells of small cell lung cancer continue to grow in the process of chemotherapy, they may compress the nearby lung tissues and trachea and bronchus, which may cause coughing. It is suggested that patients should go to the hospital in time for examination to clarify the cause of the disease and actively cooperate with doctors to receive standardized treatment to improve the symptoms.