Ciclesonide nasal spray delivers the corticosteroid ciclesonide as a hypotonic spray via a metered-dose manual pump. Systemic exposure to ciclesonide and its active metabolite desisobutyryl-ciclesonide is low after intranasal administration. High protein binding (approximately 99%) and rapid first-pass clearance further reduce systemic exposure to the drug. In well designed trials, intranasal ciclesonide 200 microg once daily for 2-4 weeks was more effective than placebo in terms of improving nasal symptoms in adolescents and adults with moderate to severe seasonal allergic rhinitis. Quality of life measures were statistically significantly improved in ciclesonide relative to placebo recipients during the first 2 weeks of therapy. Similarly, in adolescents and adults with moderately severe perennial allergic rhinitis, ciclesonide 200 microg once daily was more effective than placebo in terms of reducing nasal symptoms in well designed trials of 6 weeks' and 1 year's duration. Improvements relative to placebo in quality of life measures were not considered clinically relevant. Ciclesonide nasal spray was generally well tolerated in these clinical trials; most adverse events were mild to moderate in intensity.