Kim et al68 conducted a 4-week, multicenter, randomized, double-blind, placebo-controlled trial in 1179 subjects (66% female, 34% male; mean age, 35 years [range, 12–76 years]) with a ≥2-year history of moderate to severe PAR. Morning PNIF was sig- nificantly increased with desloratadine 5 mg/d com- pared with placebo (10.2 vs 7.6 L/min, respectively; P = 0.03); the change in evening PNIF did not differ significantly between desloratadine and placebo (11.2 and 8.9 L/min). The TSS (including nasal congestion) was significantly reduced with desloratadine com- pared with placebo as early as day 2 (−2.3 vs −1.7; P = 0.001).