The objective of the study is to evaluate the efficacy and tolerability of Bilastine 20 mg, compared to Cetirizine and placebo for the treatment of seasonal allergic rhinitis.

In this pivotal, multicentre, international, randomized, double-blind, placebo and active-comparator controlled, parallel study, 683 patients with SAR will be enrolled. Patients will be required to be 12-70 years old, have SAR for ≥2 years, a positive skin test, total nasal and non-nasal score (TSS) ≥36 (out of 72) during run-in, and a composite instantaneous nasal symptom score ≥6 (out of 12) the morning before randomization. The primary efficacy endpoint will be the AUC of reflective TSS from baseline to Day 14.

Inclusion Criteria:

• Patients of either sex between 12 and 70 years of age.
• Patients with documented clinical history of SAR, for at least 2 years prior to the study inclusion.
• Positive skin prick test for at least one of the seasonal allergen specific of the geographical area.
• A previous positive Prick test, or a positive IgE Test (RAST) may also be accepted for inclusion, if performed within 12 months prior to the inclusion.

Exclusion Criteria:

• Patients who have non-allergic rhinitis (vasomotor, infectious, drug-induced, etc.).
• Negative skin prick test (as defined in point 6.1.1.).
• Patients with nasal polyps or a significant deviation of the nasal septum as judged by the investigator as well as nasal intervention in the previous 6 months. Any other nasal illness that can interfere with the aim of the study.
• Patients who have acute or chronic sinusitis as judged by the investigator.
• Patients who have received anti-allergy immunotherapy in the previous two years or are still receiving this kind of therapy.
• Patients who are taking or have taken specified medications prior to randomisation in the study and have not complied with the specified washout period