How is asthma diagnosed? 1.Recurrent episodes of wheezing, dyspnea, chest tightness or coughing, mostly associated with exposure to allergens, viral infections, exercise or certain irritants. 2.Diffuse or scattered rales, mainly in the expiratory phase, can be heard in both lungs during an attack. 3.The above symptoms may be relieved by treatment or on their own. 4. Exclude other diseases that may cause wheezing or dyspnea. 5, for atypical symptoms (such as no obvious wheezing or signs), at least one of the following tests should be positive: ① If the basal FEV1 (or PEF) <80% < span="">normal value, inhalation of β2 agonist FEV1 (or PEF) increased by more than 15%. ② PEF variability (measured by peak expiratory flowmetry, once in the early morning and once at night) ≥20%. ③ Positive bronchial provocation test (or exercise provocation test).