Antihistamines are effective medications that have been used for decades in the management of allergic rhinitis; however, they may be administered or selected in an inappropriate fashion and may be the source of drug-related morbidity. Our objective is to present relevant background information and an expert consensus statement on the use of antihistamines in treatment of allergic rhinitis. In July 2002, 14 experts in allergy, clinical immunology, pharmacology, and impairment assessment were invited to participate in a roundtable conference to present current concepts and develop a consensus statement on the clinical management of allergic rhinitis with antihistamines. Many of the antihistamines used to treat allergic rhinitis, as well as the disease itself, may produce sedation, impairment, and reduced quality of life. Allergic rhinitis is more appropriately managed with the relatively nonimpairing second-generation antihistamines (eg, loratadine, desloratadine, cetirizine, and fexofenadine), because older agents (eg, diphenhydramine, chlorpheniramine, and brompheniramine) produce sedation and impairment and worsen sleep architecture. Although there is some debate surrounding the varying degrees of efficacy of second-generation antihistamines, it is known that some agents may produce varying levels of drowsiness or impairment, especially at higher than recommended doses. The differences with regard to safety among the second-generation antihistamines are smaller than are the differences between the first and second generations. A nonsedating, nonimpairing (even at higher than recommended doses), second-generation antihistamine is preferred for all patients, particularly those with a higher risk for the development of adverse effects. We recommend that primary care and specialist physicians, nurse practitioners, physician assistants, pharmacists, and all other health professionals involved in the diagnosis and treatment of allergic rhinitis follow this consensus document and share this information with patients for whom antihistamine therapy is recommended. In addition, further epidemiologic studies on the effects of antihistamines should be performed. (J Allergy Clin Immunol 2003;111:S835-42.)