The primary outcome will be therapeutic failure in the two groups from randomization to day 8. This failure will be defined as unscheduled medical visits for asthma symptoms or hospitalization or treatment with oral corticosteroids outside the experimental protocol. Secondary outcome measures include comparison of the number of salbutamol treatments, changes in the previously validated daytime symptoms scale, nighttime cough/awakening scale, number of asthma-free days within the 8 day observational period in the two groups, changes in the PI and PRAM scores to 48 hours and day 8 as well as the association between the main treatment effect and age, pulmonary index at randomization and history of atopy.