White phlegm in the throat is still due to an inflammatory reaction in the throat. There are more causes of inflammation, like viral infections, bacterial infections, and mycoplasma and chlamydia infections can also cause inflammation in the throat. Congestion and edema can occur at the site of inflammation, and the inflamed mucosa can become detached and necrotic. In addition, neutrophils, or eosinophils or phagocytes in the body will gather at the site of inflammation to engulf foreign pathogens. After phagocytosis of foreign pathogens, these cells undergo lysis and necrosis and mix with inflammatory exudate and shed epithelial cells to form sputum. In the case of viral infections, white sputum is usually formed. In the case of bacterial infections, yellow pus sputum is formed. In addition, mycoplasma and chlamydia infections also form white sputum, which needs to be treated with targeted medication according to the type of infection.