Objective: To evaluate whether early anti-inflammatory therapy with nebulized cromolyn sodium or budesonide reduces wheezing after bronchiolitis.

Design and setting: A randomized, controlled study in a university hospital that provides primary hospital care for all pediatric patients in a defined area.

Patients: One hundred consecutive infants younger than 24 months treated in the hospital for acute bronchiolitis.

Interventions: Thirty-four patients received cromolyn sodium, 20 mg four times a day for 8 weeks and 20 mg three times a day for 8 weeks, and 34 patients received budesonide, 500 micrograms twice a day for 8 weeks and 250 micrograms twice a day for 8 weeks, by a foot pump with a face mask; 32 patients in the control group received no therapy.

Main outcome measures: Numbers of physician-diagnosed wheezing episodes, hospital admissions for bronchial obstructions, and symptomatic days recorded by the parents.

Results: Children in the cromolyn sodium (19%) and budesonide (16%) groups had significantly fewer physician-diagnosed wheezing episodes than those in the control group (47%) during the second 8-week period (P < .05). A significant reduction in hospital admissions for bronchial obstructions was seen in the budesonide group and in the children with atopy in both treatment groups (P < .05). The children with atopy had significantly more subsequent wheezing episodes and hospital admissions than those without atopy (P < .05). The numbers of symptomatic days did not differ significantly among the three groups.

Conclusions: Early anti-inflammatory therapy with nebulized cromolyn sodium or budesonide reduces the number of wheezing episodes and hospital admissions after bronchiolitis. Children with atopy are at high risk of subsequent wheezing episodes, and they particularly benefit from anti-inflammatory therapy.