The sputum is white because there is no combined bacterial infection or the sputum formation time is not long. It is commonly found in chronic bronchitis, bronchial asthma, early stage of pneumonia, alveolar cell carcinoma and so on. 1. Chronic bronchitis: the main symptom is repeated coughing, coughing up sputum, and the sputum is usually white mucus or slurry foamy. 2. Bronchial asthma: chronic inflammation of airways leads to airway hyperresponsiveness, triggering cough, wheezing and other symptoms; sputum increases when the acute attack of bronchial asthma starts to relieve, and it is white sputum without bacterial infection. 3. Early stage of pneumonia: In the early stage of pneumonia, especially viral pneumonia, Mycoplasma pneumonia and Chlamydia pneumonia, sputum remains in the airway for a short period of time because of the absence of bacterial infection, and the sputum is white in color. 4. Alveolar cell carcinoma: coughing and sputum are early symptoms of alveolar cell carcinoma, coughing up a large amount of white mucus sputum, if accompanied by infection, the amount of sputum will further increase, and purulent sputum may appear. In addition, coughing up white sputum can also occur in chronic obstructive pulmonary disease (COPD). If the symptom of coughing up white sputum fails to improve or even worsens gradually, it is necessary to consult a regular hospital in time, and cooperate with the doctor to improve the examination and standardize the treatment.