The nose and lung are both part of the respiratory tract. Often the diseases affecting the nose and/or the bronchi are treated separately. However, in recent years, numerous studies have highlighted the fact that the respiratory system is a single entity and the concept of "united airway disease" has become more and more important. The unity of the respiratory tract is confirmed both from a morphological and from a functional point of view. Nevertheless, this concept is also confirmed for the respiratory immune system, innervation and vascularization interesting all along the tract, from the nose to the bronchioles. When treating rhinitis, it is often necessary to assess the presence of asthma. Patients with sinusitis should be evaluated for a possible concomitant asthma. Conversely, patients with asthma should always be evaluated for possible nasal disease. The medications that treat nasal diseases appear to be useful in improving control of asthma and in reducing bronchial hyperresponsiveness as well. Physicians should always keep these notions in mind, and evaluate and treat respiratory diseases taking into account the unity of the respiratory tract.
Keywords: ARIA; Airways; allergic rhinitis; asthma; rhinosinusitis; united airways.