Several studies have shown that bronchodilation with β-adrenergic agents such as salbutamol may improve symptoms briefly but do not affect the overall course of the illness or reduce the need for hospitalization. However, there are conflicting recommendations about the use of a trial of a bronchodilator, especially in those with history of previous wheezing, due to the difficulty with assessing an objective improvement in symptoms. Bronchiolitis-associated wheezing is likely not effectively alleviated by bronchodilators anyway as it is caused by airway obstruction and plugging of the small airway diameters by luminal debris, not bronchospasm as in asthma-associated wheezing that bronchodilators usually treat well.