Yellow phlegm can be coughed up from the throat, usually because there is a bacterial infection in the throat, and it becomes septic. Suppuration occurs because neutrophils in the body gather in the throat and engulf foreign bacteria, and the neutrophils become lysed and necrotic. In addition, there are inflammatory exudates in the pharynx, and the mucosal epithelium of the pharynx is shed and necrosis occurs due to inflammation. All these substances are mixed together to form yellow sputum. Treatment with antibiotics is necessary for the phenomenon of yellow sputum. Drugs that are more effective for upper respiratory tract infections are cefradine or cefadroxil, and amoxicillin clavulanic acid potassium, provided that no allergies to these drugs occur. In addition, the cause of coughing up yellow sputum may be bronchial dilation, which can be clarified by CT or MRI examination of the chest. If it is indeed a case of bronchial dilatation, it is important for the patient to have sputum removal treatment every morning.