Bronchiolitis is the most common acute infection of the airways and lungs during the first years of life. It is caused by viruses, the most common being respiratory syncytial virus. The illness starts similar to a cold, with symptoms such as a runny nose, mild fever and cough. It later leads to fast, troubled and often noisy breathing (for example, wheezing). While the disease is often mild for most healthy babies and young children, it is a major cause of clinical illness and financial health burden worldwide. Hospitalisations have risen in high-income countries, there is substantial healthcare use and bronchiolitis may be linked with preschool wheezing disorders and the child later developing asthma.

There is variation in how physicians manage bronchiolitis, reflecting the absence of clear scientific evidence for any treatment approach. Anti-inflammatory drugs like glucocorticoids (for example, prednisolone or dexamethasone) have been used based on apparent similarities between bronchiolitis and asthma. However, no clear benefit of their use has been shown.

Our systematic review found 17 controlled studies involving 2596 affected children that used these drugs for a short duration and assessed short-term outcomes. When comparing glucocorticoids to placebo, no differences were found for either hospital admissions or length of hospital stay. There was no substantial benefit in other health outcomes. These findings are consistent and likely to be applicable in diverse settings.

Exploratory results from one large high-quality trial suggest that combined treatment of systemic glucocorticoids (dexamethasone) and bronchodilators (epinephrine) may significantly reduce hospital admissions. There were no relevant short-term adverse effects that were any different from those seen with an inactive placebo, while long-term safety was not assessed. Further research is needed to confirm the efficacy, safety and applicability of this promising approach.