The appearance of yellow sputum from a cold is not a sign that the disease is almost over, but is due to the invasion of the organism by pathogens, the appearance of congestion and edema of the mucous membrane of the upper respiratory tract, and the exudation of a large amount of inflammatory substances. The appearance of yellow sputum indicates a combination of bacterial infection, and the appearance of a large amount of purulent, yellow secretions, which contain a large number of necrotic and live bacteria, as well as detached tissue fragments and a large amount of inflammatory secretions. At this time, it is recommended that blood tests can be performed to clarify the condition and cause. Antibiotics, such as penicillin, amoxicillin, cefoperazone, cefuroxime, erythromycin, azithromycin, or levofloxacin, can be used appropriately. Follow up with the doctor at any time to adjust the treatment plan.