A 2-week randomized double-blind parallel-group comparison study of dexamethasone cipecilate (NS-126C) was conducted to verify efficacy at 400 μg/day QD in these with perennial allergic rhinitis versus fluticasone propionate (FP) nasal solution at 200 μg/day BID and NS-126C placebo. Of the 406 subjects included in the FAS (NS-126C: 162; FP: 161; placebo: 83), changes in total nasal symptom scores for sneezing, rhinorrhea, and nasal congestion as the primary endpoints, were −2.03±1.95 in the NS-126C group and −2.10±1.77 in the FP group, yielding a group difference in change (95% confidence interval) of 0.07 (−0.32 to 0.46). The maximum 95% confidence interval of 0.46 was lower than the predetermined noninferiority margin (Δ=0.6), demonstrating NS-126C noninferiority to FP. Both comparison drugs were superior to placebo (p<0.001). Patient population safety showed no significant difference between the two drug groups in the incidences of adverse events or adverse drug reactions. The incidence of nasal discomfort as an adverse drug reaction was 0.6% (1/162) in the NS-126C group and 3.1% (5/161) in the FP group, indicating that the NS-126C powder preparation elcited fewer adverse nasal cavity drug reactions. These findings verified noninferior NS-126C efficacy administered at 400 μg once daily compared to fluticasone propionate nasal solution administered twice daily. NS-126C is thus effective and safe in treating allergic rhinitis.