Coughs can be categorized into acute, subacute and chronic coughs according to the onset of the disease, and dry and wet coughs according to the presence or absence of sputum. 1. Classification according to the urgency of onset (1) Acute cough: the course of the disease within 3 weeks, mostly seen in upper respiratory tract infection, acute bronchitis and other diseases. (2) subacute cough: the duration of the disease in 3 ~ 8 weeks, seen in the cold cough, asthma and so on. (3) Chronic cough: the duration of the disease is more than 8 weeks, seen in cough variant asthma, gastroesophageal reflux and so on. 2. Classification according to the presence or absence of sputum (1) Dry cough: It means that there is no sputum or very little sputum when coughing. Dry cough is common in acute pharyngitis, chronic pharyngitis, bronchial tumor, pleural disease, pulmonary hypertension and so on. (2) Wet cough: refers to coughing with sputum, commonly found in bronchiectasis, pneumonia, chronic bronchitis, cavitary tuberculosis, lung abscess and other diseases. If the symptoms of coughing are not relieved for a long time, it is recommended to seek medical treatment in time.