6: Rhinitis and asthma: united airway disease.

United airway disease is characterised by inflammation of the respiratory tract, in which asthma and rhinitis are the upper and lower respiratory tract manifestations, respectively, of the same disease process. Irrespective of cause, the upper and lower respiratory tract manifestations are characterised by a systemic inflammatory response. Patients with rhinitis or asthma should always be assessed for coexistent disease in the reciprocal area.