The most common reason for yellow sputum to white sputum is that the infection is under control and the condition is improving. If the cough and sputum are caused by bacterial infection, the most common are coughing, coughing yellow sticky sputum or white sticky sputum, sputum is sticky and not easy to cough out, etc., which mostly belong to bacterial infection. After antibiotic anti-infection treatment, the patient’s symptoms will be gradually relieved, including the change from yellow sputum to white sputum, and at the same time, it will be accompanied by the improvement of general symptoms such as better spirit and better appetite, which means that the disease is gradually reduced and has been controlled. If the change from yellow to white sputum is not accompanied by other symptoms, such as poor appetite, poor mental health, and strong wheezing, it usually does not indicate that the disease is improving. Therefore, the condition and cause of the change from yellow to white phlegm should be analyzed according to the patient’s specific condition and should not be generalized.