To determine the relative efficacy, compare the incidence of adverse events, and ascertain the systemic glucocorticoid effect of the nasal application of several doses of budesonide, 406 patients with seasonal ragweed-induced allergic rhinitis were randomized in a double-blind, parallel group design to receive intranasal budesonide aqueous pump spray (Rhinocort Aqua) 32 micrograms, 64 micrograms, 128 micrograms, 256 micrograms, or placebo once daily for 4 weeks. A total of 231 adults and 175 children participated in the study conducted at 14 centers in two geographic regions, the Midwest and the Northeast United States, during the 1994 ragweed season. Pollen counts were collected at each site by the Rotorod method. The primary efficacy parameter was the change from baseline nasal index score (NIS) for the overall study population--defined as the sum of scores for nasal congestion, runny nose, and sneezing. The study was powered only to evaluate the overall study population for statistical significance. Significant differences in NIS were observed in each active treatment group compared with placebo (p < or = 0.003). Compared with placebo, budesonide aqueous spray significantly reduced individual symptoms of runny nose and sneezing at all doses (p < or = 0.008), and nasal congestion and nasal itching at all doses except 64 micrograms (p < or = 0.022). In the Midwest pollen belt where the 1994 ragweed season was representative of a typical pollen season, it was possible to establish a dose-response relationship for comparison of budesonide aqueous spray 256 micrograms versus 32 micrograms (p = 0.017). The incidence of adverse events was similar between budesonide aqueous-treated and placebo-treated patients. Importantly, there was no effect of budesonide aqueous spray on basal or ACTH-stimulated plasma cortisol levels in either adults or children at the end of 4 weeks of treatment. Intranasal budesonide aqueous pump spray, administered once daily, was efficacious and was generally well tolerated in both adults and children with seasonal allergic rhinitis.