Cough is a very common symptom. A so-called chronic cough is one that persists for more than two months and is especially common in women. It is very common for this kind of chronic cough to have no abnormalities on chest X-ray or chest CT. I see many such patients in my outpatient clinic, and many antibiotics applied in outside hospitals do not solve the problem. I once saw a patient who had been treated externally for chronic cough for over a year with no effect. I discussed with her and she said that she often felt full and regurgitated in her stomach. Later we found out after gastroscopy that she had gastroesophageal reflux and H. pylori infection, and her cough cleared up after using some symptomatic medications. This patient had a cough caused by gastroesophageal reflux. I cite this example to show that cough is not necessarily purely an inflammation of the bronchial tubes. The causes of cough are complex and can be respiratory, digestive, or otorhinolaryngological diseases. According to the Nei Jing, “all the five internal organs and six internal organs cause coughing, not only the lungs”. Therefore, when we encounter coughing in our daily life, it should not always mean that it is a problem of the lungs. There are several types of chronic coughs with no abnormal chest images: upper airway cough syndrome, which is often caused by rhinitis and sinus lesions. Postnasal drip, glandular hyperplasia, and cobblestone-like hyperplasia in the posterior wall of the pharynx can all cause a cough. A patient with allergic rhinitis or sinusitis, sometimes not reflected in the nose but manifested as a cough, with the nose always tickling like hell, is a typical cough caused by allergic rhinitis, and after controlling the rhinitis, he does not cough anymore. The second cause of coughing is asthma. We all know about common asthma, but some patients don’t have asthma, they just cough. I have a patient from Xiangshan who coughs at 2 or 3 o’clock at night. With this one you can tell that this patient is asthmatic. We have children who run and cough in the morning and also cough a few times at night. In this case we need to pay attention to see if this child has asthma. If the symptoms are right and treated as asthma, the cough may be cured quickly. The third cause of cough is eosinophilic bronchitis. We have patients in whom no problem can be detected by any test, and when some sputum is guided by ultrasound nebulization for sputum cytology, in which eosinophils exceed 3%, this patient can be diagnosed with eosinophilic bronchitis. Antibiotics are useless in this type of patient, and treatment with some glucocorticoids will be effective. The fourth type of chronic cough is caused by stomach problems. I had a 50-year-old female patient, a native of Hengpu, with recurrent cough for more than three months, who had applied antibiotics outside continuously for more than a month without effect. The patient said he had had stomach problems, so I noticed this problem and later found out that his cough was actually caused by gastroesophageal reflux. Four weeks of omeprazole cleared it all up. In addition, some blood pressure lowering drugs (angiotensin converting enzyme inhibitors), 20% of people in China have cough after taking such drugs, which should be noted.