1. Long-term persistent cough (>3 weeks) often triggered by respiratory irritants, cold air, exercise, etc., persistent cough is the only symptom, often occurs at night and in the early morning hours, no croup on physical examination 2. family history of allergies, or history of allergies at other sites, increased peripheral blood eosinophils, increased sputum eosinophils 3. episodes are mostly seasonal, mostly in spring and autumn 4. positive bronchial excitation or dilatation test, no signs of infection antibiotics and antitussive drugs are ineffective, and the theophylline, ß2 receptor rate is normal. 5. No signs of infection, ineffective antibiotics and cough suppressants, normal chest radiograph, other causes of cough can be excluded, and theophylline, ß2 agonists or adrenocorticosteroids are effective.