If a patient’s cough sputum changes from yellow to white sputum, it is generally a sign of improvement. Yellow sputum generally represents bacterial infection. Patients with yellow sputum show elevated white blood cells, neutrophils, and neutrophil percentage in blood routine, while C-reactive protein and calcitoninogen are also higher than normal, and the diagnosis of bacterial infection is clinically clear and requires treatment with antibiotics, such as cefprozil, cefuroxime, cefixime, azithromycin, etc. If the patient’s cough decreases, yellow sputum turns to white sputum, and the patient’s white blood cells, neutrophils, neutrophil percentage, C-reactive protein, and calcitoninogen all decrease, the clinical consideration is that the condition is improving.