Background. The World Health Organization defines asthma as a disease characterized by repeated attacks of dyspnea and wheezing, which vary in frequency from person to person. According to another definition, asthma is considered a complex syndrome that cannot be classified as a single disease but as a series of overlapping individual diseases and phenotypes, the expression of which is the result of a unique interplay between genetic and environmental factors. This conglomerate of diseases is more pronounced precisely in the severe form of asthma, which by definition is the most serious and life-threatening form, the adequate control of which often cannot be achieved even with high doses of medication. Clinical experience and now genetic data are increasingly leaning towards the concept of asthma as a heterogeneous clinical syndrome; clinical cases erupt, progress and respond to treatments in different ways. Currently, the diagnosis of asthma is based on incisive clinical methods that rely on pulmonary function tests, which prove the reversibility of bronchial obstruction. But this approach alone is not enough to address the diagnostic and therapeutic challenges resulting from the heterogeneity of asthma; among others, regarding the management of asthma, current guidelines pay special attention to the identification of comorbidities and the role they play.