Yellow sputum is a common symptom of colds, because colds are infectious diseases and acute upper respiratory tract infections, which stimulate the respiratory glands to secrete more phlegm, which is manifested as coughing up sputum. If the coughing of yellow sputum persists, it is also necessary to consider the combination of bacterial infection, because most of the colds are caused by viral infections, but for a longer period of time, it is easy to combine with bacterial infections, resulting in coughing of yellow sputum or pus sputum. Therefore, blood analysis, chest X-ray, lung CT examination can be completed in time to clarify, and at the same time give anti-infection treatment, such as the use of amoxicillin, cefuroxime, cefaclor or cefprozil and other drugs.