Allergic rhinitis affects about 20% of the US population. The diagnosis is based on patterns of symptoms, physical examination, and assessment of IgE antibodies by skin or in vitro testing. The most common offending allergens are pollens of grasses, trees, and weeds; fungi; animal allergens; and dust mites. In an individual with nasal allergy, exposure leads to rapid release of mast cell—derived mediators. This immediate response is followed by a cell-dominated response, including eosinophils and lymphocytes. Cytokines from TH2 lymphocytes, such as interleukin 4 and interleukin 5, orchestrate allergic inflammation. Resulting tissue changes produce symptoms of the disease and augment responses on subsequent exposure to allergens and irritants. Strategies for avoiding offending agents are important in management. In intermittent disease, antihistamines and/or decongestants are first prescribed. More continuous symptoms may mandate intranasal steroids. lmmunotherapy is often helpful for patients who respond poorly to pharmacotherapy and avoidance.