['Intranasal corticosteroids are effective in controlling allergic rhinitis (AR) symptoms; however, chronic administration of corticosteroids may suppress hypothalamic-pituitary-adrenal (HPA)-axis function.', 'To evaluate the effects of 6 weeks of treatment with beclomethasone dipropionate (BDP) hydrofluoroalkane nasal aerosol on HPA-axis function in subjects with perennial AR (PAR).', 'In this randomized, double-blind, placebo- and active-controlled study, subjects aged 12 to 45 years were randomized to receive BDP nasal aerosol 320 μg/day (n = 50), placebo (n = 46), or placebo/prednisone (prednisone 10 mg/day for the last 7 days of the treatment period [n = 11]). The primary end point was change from baseline in 24-hour serum cortisol (SC) weighted mean (expressed as geometric mean ratio [GMR]) in the BDP and placebo group after 6 weeks of treatment.', 'Geometric SC-weighted mean values were similar in the BDP and placebo groups at baseline (9.04 and 8.45 μg/dL, respectively) and after 6 weeks (8.18 and 8.01 μg/dL, respectively). After 6 weeks of treatment, BDP was noninferior to placebo with respect to the ratio from baseline in SC-weighted mean (GMR: 0.96 [95% CI: 0.87, 1.06]). In contrast, 7 days of prednisone treatment substantially reduced geometric SC-weighted mean values from baseline (approximate 3-fold reduction [from 7.33 to 2.31 μg/dL]) compared with placebo. BDP nasal aerosol was well tolerated, and the safety profile was similar to that of placebo.'] Does once-daily treatment with beclomethasone dipropionate nasal aerosol affect hypothalamic-pituitary-adrenal axis function?