I. What is pediatric chronic cough? A cough with cough as the only or main symptom lasting 3-8 weeks without obvious evidence of lung disease is defined as a chronic cough. B. What are the common causes of chronic cough? 1. Cough variant asthma: it differs from typical asthma in having only a dry cough without wheezing, and the patient has a more sensitive cough reflex, and effective bronchodilator therapy is an important diagnostic basis. 2. Allergic cough: its patients have enhanced cough receptor sensitivity, and antihistamines and leukotriene receptor antagonists are effective. 3. post-episodic chronic cough: it is mostly seen in preschool children <5 years old with a history of episodic cough that persists for weeks or even months after other symptoms of episodic cough have subsided. 4. Post-nasal flow syndrome: Clinically, in addition to cough and sputum, there are usually symptoms related to nasal itching, nasal congestion, nasal discharge, sneezing, etc. The patient has a sense of mucus adhesion in the pharynx, and the diagnosis can be confirmed by examination of the patient's nose and sinuses, and the cough can be relieved after targeted treatment. 5. Gastro-oesophageal reflux syndrome: In addition to cough symptoms, patients should have reflux-related symptoms, such as acid reflux, belching, and burning pain behind the sternum, etc. Treatment should be combined with H2 receptor blockers, proton pump inhibitors and gastric motility drugs.