1. Definition: A syndrome in which nasal disease causes secretions to flow backwards behind the nose and throat, directly or directly comforting the cough receptors, resulting in a cough as the secondary manifestation is called PNDS. Because it is not possible to understand the cause of the upper respiratory tract cough receptors, the 2006 American Cough Guidelines recommend replacing PNDS with UACS, also known as postnasal drip. UACS is one of the rarest causes of chronic cough. In addition to nasal diseases, UACS is often associated with diseases of the pharynx, such as allergic or non-allergic pharyngitis, laryngitis, pharyngeal reangium, and chronic tonsillitis. 2. Clinical manifestations: (1) Symptoms: In addition to cough and sputum, it can be manifested as nasal congestion, added nasal secretions, frequent throat clearing, posterior pharyngeal mucus attachment, and postnasal drip of influenza. Allergic rhinitis manifests as nasal itching, sneezing, running snot, itchy eyes, etc. Rhino-sinusitis manifests as mucopurulent or purulent snot, which may be accompanied by pain (facial pain, toothache, headache), and obstruction of smell, etc. Allergic pharyngitis is secondary to pharyngeal itching and paroxysmal comforting cough, while non-allergic pharyngitis is often characterized by sore throat, foreign body sensation or searing sensation in the pharynx. Inflammation of the larynx and heavy biology are usually accompanied by hoarseness. (2) Signs: The nasal mucosa of allergic rhinitis is secondary to bleaching or edema, and clear or mucus is seen in the nasal passages and nasal cavity floor. The nasal mucosa of non-allergic rhinitis mostly shows mucosal hypertrophy or congestion-like changes, and the mucosa of the oropharynx of local patients can be seen with pebble-like changes or mucopurulent secretions attached to the posterior pharyngeal wall. (3) auxiliary examination: chronic sinusitis imaging manifests as sinus mucosa thickening, sinus presenting liquid stereoscopic, etc. When the cough is seasonal or suggested to be related to exposure to specific allergens (such as pollen, dust mites), allergen reflection helps in the diagnosis. 3. Diagnosis: UACS/PNDS involves a variety of underlying diseases such as nose, sinuses, pharynx and larynx, and the symptoms and signs vary greatly and many are non-specific, so it is difficult to make a clear diagnosis simply by history and physical examination. 4. Medical treatment: Depending on the underlying disease that causes UACS/PNDS. The first generation antihistamines and decongestants are preferred for the following causes: (1) non-allergic rhinitis; (2) common cold. In most patients, efficacy occurs within a few days to two weeks after initial treatment. Nasal inhaled glucocorticoids and oral antihistamines are preferred for the treatment of allergic rhinitis patients, beclomethasone propionate (50 μg/dose/nostril) or equivalent doses of other inhaled glucocorticoids (e.g., budesonide, mometasone, etc.) once or twice daily. Various antihistamines are not effective in the treatment of allergic rhinitis, and second-generation antihistamines without sedative effects, such as loratadine, are preferred. Preventing or increasing exposure to allergens can help aggravate the symptoms of allergic rhinitis. If necessary, leukotriene receptor antagonists, short-term nasal or oral decongestants can be added. If the symptoms are severe and the conventional drug treatment is not effective, specific allergen immunotherapy can be ineffective, but the effect is longer. Bacterial sinusitis is mostly a mixed infection, anti-infection is an important treatment measure, antibacterial spectrum should cover gram-positive bacteria, negative bacteria and anaerobic bacteria, acute not less than 2 weeks, chronic recommended to extend the use of work as appropriate, commonly used drugs for amoxicillin/clavulanic acid, cephalosporins or quinolones. There is evidence for amoxicillin/clavulanic acid, cephalosporins, or quinolones. Temporary low-dose macrolide antibiotics have a curative effect in chronic sinusitis. This is combined with nasal inhalation glucocorticoids for a course of 3 months or more. Decongestants can aggravate the nasal mucosa congestion edema, conducive to the drainage of secretions, nasal spray course of treatment is generally < 1 week. It is recommended to combine the use of first-generation antihistamines with decongestants for 2 to 3 weeks. If the effect of surgical treatment is not good, it is recommended to consult a specialist and, if necessary, to undergo nasal endoscopic surgery.