Definition of Upper Airway Cough Syndrome (UACS): Also known as Postnasal dripsy syndrome (PNDs), it refers to various rhinitis (allergic and non-allergic), sinusitis, chronic pharyngitis, chronic tonsillitis, laryngitis, nasal polyps, adenoid hypertrophy and other upper airway diseases. The syndrome is caused by the backflow of secretions into the postnasal and pharyngeal regions, or even into the vocal cords or trachea, resulting in a cough as the main manifestation. Pathogenesis of UACS: 1. Local inflammatory response in the nasopharynx stimulates upper airway cough receptors. 2, Direct mechanical stimulation of the posterior flow of nasal secretions leads to enhanced reflexes. 3. Lowering of airway cough receptor thresholds through neural reflexes and bone marrow responses leading to inflammatory responses in the lower airway. Clinical manifestations of UACS: (1) Symptoms: In addition to cough and sputum, there may be cold manifestations: nasal congestion and increased nasal secretions. There may be frequent throat clearing, retropharyngeal mucus adherence, and postnasal drip influenza. Allergic rhinitis manifestations: nasal itching, sneezing, watery snot, itchy eyes, etc. Rhino-sinusitis manifestations: mucopurulent or purulent snot, may have pain (face, toothache, headache), smell disturbance, etc. Allergic pharyngitis is characterized by pharyngeal itching and paroxysmal irritating cough, while non-allergic pharyngitis is often characterized by sore throat, foreign body or burning sensation in the throat. Inflammation of the larynx and neoplastic organisms are usually accompanied by hoarseness. (2) Signs: In allergic rhinitis, the nasal mucosa is mainly pale or edematous, and clear or mucus can be seen in the nasal passages and the floor of the nasal cavity. In non-allergic rhinitis, the nasal mucosa mostly shows mucosal hypertrophy or congestion-like changes, and in some patients, the mucosa of the oropharynx may show cobblestone-like changes or mucopurulent secretions attached to the posterior pharyngeal wall. Allergic pharyngitis is characterized by pale or edematous pharyngeal mucosa, while non-allergic pharyngitis is characterized by pharyngeal mucosal congestion or/and lymphatic follicular hyperplasia. These clinical manifestations are more common but non-specific. In the Revision 09, UACS is diagnosed with: (1) cough as the main clinical manifestation with or without postnasal drip influenza; (2) history of underlying nasal and pharyngeal disease; and (3) cough relief after treatment for nasal and pharyngeal disease. Treatment of UCAS: (1) avoidance of exposure to causative factors; (2) control of inflammation and reduction of secretions; (3) treatment of infection; (4) correction of anatomical abnormalities of the nose, etc.