Asthma is one of the most common chronic respiratory diseases worldwide. The natural history of the disease is punctuated by episodes of symptom worsening, termed exacerbations. These play an important role in the natural history of the disease, in terms of their effect on morbidity and mortality and because of the economic healthcare burden. Exacerbations are generally acute or subacute in presentation and may, in some cases, represent the initial presentation of bronchial asthma. Clinically, it is important to understand and recognise the risk factors involved in triggering an acute event. When facing a patient with suspected exacerbated asthma, clinicians must first exclude a diagnosis other than asthma and then identify potential risks for asthma-related death and assess the clinical severity of the manifestations. Proper asthma management and treatment should primarily aim to prevent and reduce, and possibly eradicate, exacerbation episodes.

Cite as: Morandi L, Bellini F, Papi A. Asthma: definition, severity and impact of pulmonary exacerbations. In: Burgel P-R, Contoli M, López-Campos JL, eds. Acute Exacerbations of Pulmonary Diseases (ERS Monograph). Sheffield, European Respiratory Society, 2017; pp. 1–12 [https://doi.org/10.1183/2312508X.0015516].