These patients have a common feature: they have a long cough with little sputum. Some of them have been using antibacterial agents for a long time, but they still have intermittent and recurrent coughs for which no cause can be found. In fact, chronic cough: Chronic cough has many causes and can usually be divided into two categories: those with clear lesions on the initial X-ray chest film, such as pneumonia, tuberculosis and lung cancer; and those with no obvious abnormalities on the X-ray chest film and cough as the main or only symptom, which is usually referred to as unexplained chronic cough (referred to as chronic cough). The common causes of chronic cough are: cough variant asthma (CVA), postnasal drip syndrome (PNDs), eosinophilic bronchitis, allergic (allergic) cough and gastroesophageal reflux cough (GERC), which account for 70% to 95% of chronic cough in respiratory medicine outpatient clinics. Others are cough caused by hypotensive drugs (ACEI class of drugs), and others, such as chronic bronchitis, bronchiectasis, endobronchial tuberculosis, and psychogenic cough.