[Asthma and allergic rhinitis as symptoms of the same disease: a paradigm under construction].

Objective: To describe current ideas about the relation between upper and lower respiratory tract and to review the epidemiological, immunological, and pathological aspects that support the paradigm of united airways disease.

Sources: Literature review using the Medline, MD Consult, HighWire, Medscape and Lilacs databases. We used allergic rhinitis and asthma as keywords, and searched articles published in the past 20 years.