The appearance of yellow sputum can be clearly identified as a respiratory infection caused by bacteria in the first place. If bacterial infection occurs in any part of the throat, trachea, bronchus, or lungs, yellow sputum may appear, for example, infection in the throat may be accompanied by yellow sputum due to the appearance of pus. When bacterial infections occur in the trachea, bronchi, and lungs, inflammatory exudation ensues from these sites, and neutrophils and phagocytes in the body gather at the inflammatory sites to engulf foreign bacteria, and subsequently these inflammatory cells undergo lysis and necrosis, and then gather at these sites and mix with the exuded inflammatory material to form yellow sputum. For bacterial infections, the most important thing is to use antibiotics for treatment. For respiratory infections, cephalosporin antibiotics or penicillin antibiotics are more commonly used, and if there is no allergy to these two drugs, cefixime and amoxicillin can be used for treatment.