Yellow sputum becomes white sputum, which is usually a change in the sputum secreted from the bronchial tubes and respiratory tract. Generally, when the yellow sputum coughed up becomes lighter white sputum, it indicates that the symptoms of coughing have been improving and the inflammation has been relatively reduced, such as the Staphylococcus aureus in the respiratory tract is decreasing. If the yellow sputum coughed up turns into thicker, fishy white sputum, it indicates that the bacteria infecting the respiratory tract are relatively high in Staphylococcus epidermidis infection and mycoplasma, which are white and attach to the sputum to form thick white sputum. At this time the cough does not get better, but instead the cough is stronger and the condition may be serious. In addition, the color of the sputum changes from yellow to white, and it may be that the inflammation changes from acute to chronic, and the inflammation decreases, but it turns into a case of prolonged inflammation, and it is likely to progress to chronic inflammation. Therefore, in the case of treatment with antibiotics, it is important to be under the guidance of a doctor, and if necessary, sputum can be taken to examine the pathogens for drug sensitivity testing.