Twelve-year-old children always have nasal discharge, may be related to upper respiratory tract infection, allergic rhinitis, sinusitis and other reasons. 1. Upper respiratory tract infection: upper respiratory tract infection is a general term for acute inflammation of the nasal cavity, pharynx or larynx, most of which is caused by viral, bacterial and other pathogens, the main manifestations of which are sneezing, running watery nose, cough, fever and other symptoms, the child’s old snotty nose can be caused by upper respiratory tract infection. 2. Allergic rhinitis: allergic rhinitis is a chronic reactive inflammation of the nasal mucosa, patients mainly manifested as nasal itching, paroxysmal continuous sneezing, a large amount of watery nasal discharge and other symptoms, patients in contact with allergens caused by the onset of allergies, may cause the situation of the old runny nose. 3. Sinusitis: Sinusitis is an inflammatory disease of the mucosa of the sinuses, mostly caused by pathogen infection, mainly manifested as nasal congestion, pus, head and face pain, loss of smell and other symptoms, when the twelve-year-old child suffers from sinusitis, there may always be the symptom of nasal discharge. It is recommended that the patient timely medical examination, clear causes for targeted treatment, pay attention to warmth in life, avoid overeating, regular review and so on.