Phase II Study Evaluating ONO-4053 and Cetirizine in Subjects With Seasonal Allergic Rhinitis

Inclusion Criteria: * The subject is aged between 18 and 65 years inclusive, and healthy with the exception of allergic rhinitis or mild asthma that does not require treatment and has provided written informed consent, which signifies an agreement to enter the study and comply with the restrictions and requirements listed in the informed consent form. * The subject exhibits a moderate to severe response to grass pollen grains in the allergen challenge chamber at Screening. Exclusion Criteria: * The subject on examination is found to have nasal structural abnormalities or nasal polyps; a history of frequent nose bleeds, nasal biopsy, nasal trauma or nasal surgery. * Pregnant or breast-feeding females.