Cough is mainly caused by respiratory diseases. If the cough does not improve, you need to go to the hospital first for an examination. It may be caused by lung infections or lung tumors, as well as allergic coughs, asthmatic diseases, and tuberculosis, which also causes recurrent cough. Routine blood tests, lung CT and tumor marker tests, sputum culture, tuberculin test, bronchoscopy if necessary, and pathological examination are also required. If the disease is caused by tuberculosis, regular treatment with anti-tuberculosis drugs such as isoniazid and rifampin is required throughout. If it is caused by a tumor in the lung, most of them require surgery and a combination of radiotherapy and chemotherapy.