A dose-and-time related-effect of oral phenyltoloxamine citrate, a Class I, H1 antihistamine compound, has been demonstrated against allergen-induced wheal-and-erythema skin reactions among 10 adults with a diagnosis of allergic rhinitis and seasonal pollinosis. Clinical improvement in the existing symptoms of rhinorrhea, nasal obstruction, pruritus and sneezing, showed a significant correlation with the inhibition of reagin-mediated skin reactivity caused by phenytoloxamine. No adverse side effects were observed. It can be concluded that oral phenyltoloxamine citrate possesses antihistaminic properties and a range of safety which make it a useful agent for the symptomatic management of upper respiratory allergy.