Identifying children at high risk for asthma in preschool wheezing is beneficial for disease control; API is a commonly used predictor of the risk of developing persistent asthma in wheezing children within 3 years of age; and low-dose daily ICS diagnostic therapy (e.g., 0.5 mg budesonide) can be used in preschool wheezing children at high risk for asthma to provide a definitive diagnosis of asthma. A definitive diagnosis of asthma is currently difficult to make in preschool wheezing children, but because more than 80% of asthma begins before age 3 years and pulmonary impairment begins in preschool, it is necessary to identify children with preschool wheezing who may develop persistent asthma. Studies have shown that the bronchial epithelial reticular basement membrane is significantly thicker and eosinophils are detectable in children with confirmed wheezing compared to control children without wheezing, indicating that airway remodeling and inflammatory responses are already present in children with wheezing. Without early intervention in children with wheezing, this can lead to reduced lung function and increased risk of asthma in adulthood. How can children with asthma be identified and diagnosed early? The Canadian Thoracic Society and Canadian Paediatric Society 2015 Diagnosis and Management of Asthma in Infants and Children states that asthma can be diagnosed in children under 5 years of age with more than 2 previous recurrent asthma-like symptoms and improvement after physician application of bronchodilators. 2015 GINA also states that asthma can be considered in patients with recurrent asthma-like attacks for whom anti-asthmatic therapy is effective. There are different phenotypes of asthma in infants and children, and their prognosis varies from phenotype to phenotype, as does the duration of treatment. Studies have shown that the Asthma Predictive Index (API) is effective in predicting the risk of developing persistent asthma in wheezing children within 3 years of age. Clinicians can use a positive API to identify children at high risk for asthma and to educate parents of children about the importance of asthma maintenance therapy. Interventions to predict primary risk factors for pediatric asthma include: (1) parental history of asthma; (2) physician-diagnosed atopic dermatitis; and (3) evidence of sensitization to inhaled allergens. Secondary risk factors for pediatric asthma prediction include: (1) evidence of food allergen sensitization; (2) peripheral blood eosinophils ≥4%; and (3) wheezing unrelated to a cold. If the asthma predictive index is positive, standardized treatment of asthma is recommended. Despite the possibility of overtreatment, anti-asthma medication significantly reduces the severity and duration of wheezing episodes in preschool children compared to the use of antibiotics. Therefore, diagnostic treatment with anti-asthmatic medication for 2 to 6 weeks is recommended for re-evaluation in preschoolers with recurrent wheezing for which antibiotic therapy has not been effective. It must be emphasized that the majority of preschool children with wheezing have a good prognosis and their asthma-like symptoms may resolve spontaneously with age. Therefore, these children must be reevaluated periodically (3-6 months) to determine the need for continued antiasthmatic therapy. The Chinese Guidelines for the Diagnosis and Prevention of Bronchial Asthma in Children state that children with API-positive wheezing are recommended to be treated according to asthma norms and evaluated regularly. The 2014 UK Guidelines for the Management of Asthma recommend that children with high, moderate and low probability asthma diagnoses be classified according to clinical assessment (including symptom characteristics, allergy history, family history, auscultatory croup, and treatment responsiveness), and that diagnostic asthma treatment may be given to children with high probability. GINA 2015 also states that children with a suspected asthma diagnosis (including wheezing children) can be treated with conventional low-dose ICS for 2-3 months on an experimental basis and assessed for response, thus providing a basis for asthma diagnosis. The inhaled budesonide suspension 0.5 mg dosage form provides a convenient treatment option for the diagnostic treatment of children at high risk of asthma and adds a powerful new weapon for clinicians. In summary, identification of children at high risk for asthma from preschool wheezing children facilitates disease control; API is now commonly used to predict the risk of developing persistent asthma in wheezing children within 3 years of age; and low-dose daily ICS diagnostic therapy (e.g., 0.5 mg budesonide) can be used in preschool wheezing children at high risk for asthma, thus providing a basis for a definitive diagnosis of asthma.