Role of antihistamines in ocular allergy

Although H1 antihistamines are commonly used to treat allergic disorders and have demonstrated efficacy in allergic rhinoconjunctivitis, data on the effects of these agents specifically on ocular symptoms are limited. Oral H1 antihistamines inhibit some symptoms of pruritus and erythema in laboratory models and have been shown to be superior to placebo for relief of symptoms in clinical trials. Eye drops typically provide faster relief of ocular symptoms than oral agents, and combination therapy with a topical agent and an oral agent has been found to be superior to the oral agent alone. In general, oral H1 antihistamines have been considered superior to intranasal corticosteroids for relief of ocular symptoms, but some studies have shown equal efficacy for these agents, or even superior efficacy for intranasal corticosteroids.