Most of white sputum is upper respiratory tract infection caused by viral infection, and sputum is caused by viral invasion of the airway of the pharynx leading to increased secretion of mucous membranes, mainly by drinking more water and applying cough suppressant and expectorant medicines. If yellow sputum is considered to be bacterial infection, the virulent effect of bacteria damages the cells of mucous membrane as well as bacteria, which are phagocytosed by neutrophils and then lysed, releasing purulent fluid, and you should also use cough-suppressing and expectorant drugs, and add antibiotic drugs. During the treatment period, attention should be paid to drinking more water and eating more vegetables, as well as actively quitting smoking, which is very damaging to the airways and can cause destruction of lung elastic fibers and induce emphysema.