Children with long-term phlegm suggest the following possibilities: First, pay attention to whether the child has chronic infectious diseases, such as chronic pharyngitis and chronic bronchitis caused by mycoplasma and chlamydia infections. In this case, antibody tests for mycoplasma and chlamydia can be done. If there is infection can choose to use macrolide antibiotic treatment, such as azithromycin. Second, pay attention to whether the child has chronic rhinitis, sinusitis. When there is the above-mentioned condition, rhinitis and sinusitis cause an increase in respiratory and nasal secretions, and backflow into the airway can lead to an increase in phlegm secretions in the airway, resulting in long-term, recurrent episodes of phlegm symptoms. Third, pay attention to the presence of allergic factors in children, because children with allergies have increased respiratory sensitivity and increased secretions.