Coughing and coughing sputum is a clinical symptom of the respiratory system. Coughing is a reflexive defensive action by which respiratory secretions and foreign bodies in the airways can be removed, and sputum is mucus from secretions in the trachea and bronchi or exudates in the alveoli, which are expelled with the help of coughing. If there is only cough and sputum without other accompanying symptoms, such as fever, hemoptysis, pus sputum, chest pain, dyspnea, etc., occasional mild cough. There is a little clear sputum, which can be considered as physiological defense reaction; there is also long-term smoking, choking on food and water, which can also have cough and sputum; if the cough is after catching cold or flu, accompanied by white mucous sputum or foam-like sputum, it is mostly seen in acute upper and lower respiratory tract infections and acute bronchitis; long-term cough and sputum can also be seen in chronic bronchitis, and the recovery period of pneumonia can also have cough and sputum.