Allergic rhinitis is the most common manifestation of atopic disease in children and results in significant direct and indirect health care costs Peak incidence occurs in childhood and affects up to 40% of children and adolescents Although allergic rhinitis is not life threatening, it dramatically impacts the quality of life of affected children and leads to significant health care utilization and costs Severe nasal symptoms have been associated with poor school performance, and, complications of untreated allergic rhinitis include sinusitis, acute asthma, sleep disturbances, dyssomnia, and the effects of chronic mouth breathing Pathophysiology and Classification Allergic rhinitis is caused by an IgE-mediated hypersensitivity response of nasal mucosa to foreign allergens Following sensitization to foreign antigens, reexposure triggers an immediate hypersensitivity reaction The early response is characterized by mast cell activation and the release of biochemical mediators including histamine, prostaglandins, and leukotrienes These mediators cause vasodilation, mucosal edema, rhinorrhea, stimulation of itch receptors, and cough Historically, allergic rhinitis has been categorized as seasonal or perennial Seasonal allergic rhinitis is commonly caused by exposure to tree pollens (early spring), grass pollens (late spring and early summer), and ragweed or other weed pollens (late summer and fall) Allergens responsible for perennial allergic rhinitis include animal dander, house dust mites, and mold spores Allergic rhinitis is classified by symptom frequency and duration (intermittent 4 weeks per year) as well as by severity (mild or severe based on whether symptoms interfere with quality of life)