In our daily life, we often encounter coughing. Coughing is a defensive reflex action of the body and is one of the most common symptoms that can be caused when the mucous membrane of the entire respiratory tract, from the nasopharynx to the small bronchi, is irritated. There are many diseases that can cause coughing, but the main ones are lung and pleural diseases. Among respiratory diseases, infection is the most common cause, including pharyngitis, bronchitis, pneumonia, lung abscess, and tuberculosis. Cough is also one of the most common symptoms of lung cancer. In the early stage of lung cancer, it is often an irritating dry cough with no or little sputum. When the tumor causes bronchial stenosis, it can aggravate the cough, which is mostly persistent, with a high-pitched metallic sounding cough or irritating choking cough. Fine broncho-alveolar cell carcinoma may have large amount of mucus sputum. When the tumor is accompanied by infection, the sputum volume may increase and be mucopurulent. In clinical practice, there are quite a number of lung cancer patients whose earliest symptom is cough, but they did not care about it at that time and missed the best time for treatment. Whenever I come across such cases, I feel sorrowful for them. Therefore, I suggest that if you have a sudden cough that occurs more often or lasts longer recently, you should be alert and go to the hospital as soon as possible to check the cause of the cough, identify and treat the disease, and build a solid line of defense for your health.