1. A clear diagnosis can be made at the time of consultation. 1. Recurrent episodes of wheezing, shortness of breath, chest tightness or cough, mostly related to exposure to allergens, cold air, physical and chemical stimuli, as well as viral upper respiratory tract infections and exercise, often occurring or intensifying at night and/or early in the morning. 2. Scattered or diffuse, predominantly respiratory phase rales can be heard in both lungs during episodes, with prolonged respiratory phase. 3. 3. The above symptoms and signs can be relieved by treatment or self-relieved; 4. Except wheezing, shortness of breath, chest tightness and cough caused by other diseases. 1. early onset transient (mostly associated with prematurity and parental smoking, most of the children disappear within 3 years of age); 2. early onset persistent wheezing (onset before 3 years of age, associated with acute respiratory viral infection, no personal or family history of allergic diseases, wheezing symptoms usually last until school age, and a significant proportion of patients still have symptoms at 12 years of age); 3. 3. delayed wheezing/asthma (also known as IgE-associated wheezing, with a typical background of allergic disease and asthma symptoms that often persist into adulthood). The diagnosis of asthma should be highly considered if the infant or child with clinically suspected asthma has significant eczema or allergic rhinitis, or if there is a family history of asthma or allergic rhinitis (especially in the parents). Primary risk factors: 1. parental history of asthma; 2. eczema in the child; 3. evidence of inhalation allergen sensitization; secondary risk factors: 1. evidence of food allergen sensitization; 2. peripheral blood eosinophils >4%; 3. wheezing unrelated to colds; if the infant or child with suspected asthma has wheezed ≥4 times in the past year and has one primary risk factor or two secondary risk factors, then the diagnosis of asthma should be considered. 4. It is necessary to observe the response after experimental treatment to make the diagnosis. The diagnosis of asthma is supported by the use of bronchodilators and anti-inflammatory agents (hormones, leukotriptan regulators), which are effective, and the worsening of symptoms when treatment is stopped. If treatment with inhaled glucocorticoids, leukotrireceptor antagonists or bronchodilators is ineffective, the diagnosis of asthma needs to be reviewed. 5. Asthma should be suspected in any infant or child with recurrent wheezing and coughing episodes, and the diagnosis can only be confirmed by long-term follow-up, extensive identification and observation of response to bronchodilators and or anti-inflammatory therapy. “Repeated wheezing” is an important symptom of asthma, but any “recurrence” starts with the first time, so infants and children who have had a wheezing episode must be followed up regularly and the diagnosis should not be easily confirmed or excluded. 6. Further auxiliary examinations are needed to exclude other diseases before diagnosis. For example, abnormal tracheal development, bronchial foreign body, pneumonia, food allergy, etc.