Interaction between rhinitis and asthma: state of the art.

Rhinitis and asthma are very prevalent allergic disorders with comorbid features, similar risk factors, and environmental triggers. Pathophysiological processes are linked via tissue histopathology, immunologic pathway, and inflammatory mediators. Allergen challenge of the upper airway can increase lower-airway responsiveness and allergen challenge of the lower airway can lead to upper-airway inflammation. Both allergic rhinitis and asthma exert a high social and economic burden in significant loss of work and school days as well as impairment for children and adults.