BackgroundNasal airflow, as measured by rhinomanometry, is frequently impaired in allergic rhinitis (AR). The decongestion test evaluates whether the application of an intranasal vasoconstrictor drug increases nasal airflow. ObjectiveThe aim of this study was to define the characteristics of decongestion test responders. Methods123 subjects (112 males and 11 females, mean age 22.9±5.7 years) with AR were studied. Nasal eosinophils, rhinomanometry, and decongestion test were assessed in all subjects. ResultsThe optimal cut-off for % variation of nasal airflow and nasal eosinophils >5 was =34.4, with sensibility=82.7% (95%CI 73.7–89.6) and specificity=80% (95%CI 59.3–93.1). ConclusionsThe clinical relevance of this study is that non-responders may have a likely moderate–severe allergic inflammation that should be adequately evaluated and treated.