Topical antihistamines in the treatment of seasonal allergic rhinoconjunctivitis with equal or greater effectiveness when compared to systemic antihistamines in monotherapy

Background: It has been estimated that seasonal allergies affect up to approximately 44% of the population. Many people compromise the quality of their lives in order to function on a day to day basis. There are several treatments that are available in alleviating symptoms related to seasonal allergies, but many people have difficulty adhering to certain recommended regimens. Intranasal corticosteroids have been thought of as the first line of therapy in the treatment of seasonal allergies, but these require daily treatments. Systemic antihistamines, on the other hand, provide allergic relief on an as-needed basis, but are subject to a higher possibility of side effects as they are systemically metabolized. Topical antihistamines are a class of medications that could possibly provide similar, if not better, effectiveness in symptomatic control of seasonal allergies. Methods: The focus of this study was to review clinical trials providing comparison between topical antihistamines and systemic antihistamines. Clinical trials within the last fifteen years comparing topical antihistamines with systemic antihistamines and with placebos, were carefully selected and analyzed. Double-blinded and randomized clinical trials of specific topical antihistamines and systemic antihistamines were identified by a systematic literature search using MEDLINE, CINAHL, and PUBMED search engines. Results: Based on the seven randomized, double-blinded, and placebo controlled clinical trials, the efficacy of topical antihistamines was significantly greater than systemic antihistamines. Both topical and systemic antihistamines significantly improved symptoms compared to placebo. Conclusion: Overall, topical and systemic antihistamines reduced seasonal allergy symptoms, particularly allergic rhinoconjunctivitis. This review confirms the effectiveness of topical antihistamines when compared to systemic antihistamines