Coughing is a physiological reflex that occurs when the respiratory system is irritated and is a sign of self-protection. However, in a disease state, coughing may be a sign that the body is sick, especially if the cough is recurrent for more than 8 weeks, and many patients have undergone major tests such as chest CT, but still cannot find the root cause of the disease. There are many causes of chronic cough, but in general they can be attributed to four types: cough variant asthma, gastroesophageal reflux cough, upper airway cough syndrome, and eosinophilic bronchitis. Cough variant asthma is a specific type of “asthma”. The cough is the only or main discomfort, without obvious symptoms such as wheezing or shortness of breath, but it is usually severe, with nocturnal coughing as an important feature. Cold, cold air, dust, fumes, etc. can easily trigger or aggravate the cough. Gastroesophageal reflux cough. In addition to cough, patients often have heartburn, retrosternal burning sensation, acid reflux, belching and other discomforts, especially dry cough in daytime and upright position, and eating acidic and greasy food can easily trigger or aggravate the cough. Patients with upper airway cough syndrome often have underlying diseases of the upper airway such as the nose, sinuses, pharynx, and larynx, while some patients have a high percentage of eosinophils in their sputum despite being “quadriplegic” and may have eosinophilic bronchitis. Of course, a very small number of patients have a cough that is not organic but is simply due to psychological factors such as work stress or emotions, i.e. psychogenic cough. In short, when coughing affects your work life or the lives of those around you, and when coughing persists, please visit a respiratory clinic promptly!