We previously demonstrated in a group of patients with perennial allergic rhinitis alone, impairment of spirometric parameters and high percentage of bronchial hyperreactivity (BHR). Thus, the present study aimed at evaluating a group of subjects suffering from seasonal allergic rhinitis alone to investigate the presence of spirometric impairment and BHR both during and outside the pollen season.

Methods: One-hundred rhinitics sensitized to pollen allergens only were evaluated during and outside the pollen season. Spirometry and methacholine bronchial challenge were performed.

Results: Four rhinitics showed impaired values of FEV₁ without referred symptoms of asthma during the pollen season. FEF 25–75 values were impaired in 17 rhinitics during the pollen season and in 11 rhinitics outside the pollen season (P<0.05). Fifty-four patients showed positive methacholine bronchial challenge both during and outside the pollen season. PD20/FEV₁ methacholine was lower during the pollen season than outside (P<0.05). In BHR positive patients, reduced values of FVC (P<0.05), FEV₁ (P<0.05), and FEF 25–75 (P<0.01) were significantly demonstrated in comparison with BHR negative rhinitics. There was a relationship between BHR degree and FEF 25–75 values only during the pollen season (P<0.001).

Conclusions: This study evidences that an impairment of spirometric parameters may be observed also in patients with seasonal allergic rhinitis alone during the pollen season. A high percentage of these patients had BHR. A close relationship between upper and lower airways is confirmed also in the model of pollen allergy. Thus, a careful evaluation of lower airways should be performed also in those patients with seasonal allergic rhinitis alone.