Coughing up white sputum may be caused by viral infections, bronchitis, allergic asthma, cough variant asthma, and mycoplasma infections. 1. Viral infection. For patients coughing up white sputum, viral infections are more common among infectious factors. Viral infections lead to an increase in airway secretions, at which time the sputum is usually white. 2. Tracheitis. Various physical and chemical factors cause bronchitis, chronic bronchitis, etc., usually also appear cough, cough white sputum phenomenon. 3. Allergic asthma. Manifested as irritating cough, asthma attacks in the airway secretion of mucus more, and even the formation of mucus plugs, there will be a cough of white sputum phenomenon. 4. Cough variant asthma. Some asthma patients to cough as the main manifestation, if there is a chronic cough while coughing white sputum, especially with pollen, cold air and other allergens related, need to consider whether the cough variant asthma. 5. Mycoplasma infection. No obvious yellow sputum, but cough symptoms are more severe. Because the infection will cause increased airway reactivity, there will be white foamy sputum, which is more common. Cough white sputum, please go to the hospital as soon as possible to check, clarify the cause of the disease, and active treatment.