Coughing up yellow sputum is mainly considered to be due to bacterial infection, which can occur in bronchitis and pneumonia. If the yellow sputum changes to white sputum and the amount decreases, this is a positive development, and the patient’s systemic symptoms will gradually decrease. If there was fever before, it will gradually subside. At this point, it is still necessary to continue to take oral antibacterial and anti-inflammatory drugs to consolidate the treatment. In Chinese medicine, this condition is caused by wind-heat cold and phlegm-heat in the lungs. The change of yellow sputum to white sputum is also a development to the good side, which indicates that the heat has gradually subsided, and medicines for clearing heat and removing fire can be appropriately reduced. If the phlegm does not decrease but increases instead, and the patient’s symptoms are not alleviated, it does not mean that there is an improvement. Especially at this time, the body’s resistance is weaker, if there is another viral infection or feel the wind and cold, it is also easy to cause this phenomenon.