Children breathe and feel phlegm in the throat for the following reasons: 1. Hypoplastic laryngeal cartilage: Since children are just born, the development of each organ system is immature, so phlegm in the mouth and pharyngeal cavity is not easy to cough out, and the symptom of phlegm in the throat appears. When the child develops well, this symptom can subside; 2. cold, fever: coughing after cold, fever, phlegm in the throat, which affects the sleep and diet of the child, then inflammatory infection is considered, and systematic examination and treatment is needed, and oral medicine is taken to reduce phlegm and cough.