In this review, an evidence-based medicine approach to diagnosis and treatment for allergic rhinitis is reviewed. We performed a search of the medical literature for randomized, placebo-controlled trials of nonsedating antihistamines, intranasal corticosteroids, montelukast, azelastine, allergen immunotherapy, and anti-IgE. The mean numbers needed to treat were: nonsedating antihistamines--15.2; nasal corticosteroids--4.4; montelukast--14.3; azelastine--5.0; allergen immunotherapy--4.6; and anti-IgE--12.4. Treatment thresholds for use were: antihistamines--23%; nasal corticosteroids--8%; azelastine--16%; montelukast--8%; anti-IgE--50%; and immunotherapy--25%. When used appropriately, this information could become very useful for clinicians, particularly if cost, convenience, and other indirect factors can be included.