ABSTRACT
Allergic rhinitis, the most common allergic disease, affects about 20% of the adult population (1). Allergic asthma varies in prevalence in different countries, but in the Western world it usually affects more than 5% of the population (2). These diseases, which predominantly affect children and young adults, impair both physical and cognitive functions and quality of life (3). The anatomy and physiology of nasal and bronchial mucosa are very similar, and most patients with allergic asthma also have rhinitis (4). The coincident upper and lower airway dysfunction suggests a continuum of disease between rhinitis and asthma. This is the basis for the concept that the upper and the lower airways be considered a single entity, influenced by a common and evolving inflammatory process, which may be sustained and amplified by interrelated mechanisms (5).
