The presence of a cough with white sputum and foam indicates an infection of the respiratory system. The cause of infection is often viral, and mycoplasma or chlamydia is not excluded. The infected area is congested and edematous and secretes inflammatory exudates. Eosinophils, basophils, or phagocytes in the body may also accumulate in the inflamed areas of the respiratory system to engulf foreign pathogens. These cells are then shed and necrotic, and mixed with these inflammatory exudates, resulting in white sputum with foam. Treatment with antiviral drugs or anti-mycoplasma or chlamydia drugs is required. First of all, C-reactive protein, blood tests and mycoplasma antibodies should be checked. If the manifestation of mycoplasma antibodies is positive, azithromycin or erythromycin can be used for treatment. If the increase in C-reactive protein is simple, it is often a viral infection and can be treated with antiviral drugs, such as ribavirin pellets or Four Seasons Antiviral Combination.