Asthma exacerbations occur unpredictably, are a cause of morbidity and mortality, and contribute significantly to increased healthcare costs. Inhaled corticosteroids reduce exacerbations and improve quality of life.

Recent findings: The aetiopathology of asthma exacerbations is heterogeneous. Attempts to phenotype the heterogeneity of the pattern of airway inflammation by noninvasive monitoring of airway inflammation has identified a subgroup of patients with eosinophilic inflammation who are most likely to respond to steroid therapy. Strategies directed to normalize eosinophilic airway inflammation with corticosteroids have consistently led to a marked reduction in exacerbations. In contrast, their role in modulating the natural history of disease is less certain.

Summary: In the near future, improvements in our understanding of the mechanisms of exacerbations may identify therapeutic targets. While we await these developments, inhaled corticosteroids remain the first choice anti-inflammatory therapy for asthma.