The purpose of this study is to evaluate the relative efficacy of four dosing regimens of bilastine tablets versus placebo in subjects with SAR exposed in controlled ragweed pollen using the EEC model based on the mean change from baseline in Total Nasal Symptom Scores (TNSS). Study includes male and female subjects, aged 18 and 65 years with clinical history of SAR with seasonal onset and offset of nasal allergy symptoms during each of the last two ragweed allergy seasons and a positive skin prick test to ragweed allergen within 12 months prior to randomization.

Inclusion Criteria:

• Clinical history of SAR for the last two ragweed allergy seasons.
• A positive skin test within 12 months of screening to ragweed allergen.
• A minimum qualifying symptom score on both Visits, 2 and 3.
• Females must have a confirmed absence of pregnancy according to a negative urine pregnancy test.

Exclusion Criteria:

• Women who are pregnant, breastfeeding, or planning a pregnancy.
• History of more than mild asthma.
• History of clinically significant (as determined by the Investigator) active perennial allergic rhinitis to which the subject is regularly exposed.
• Non-allergic rhinitis (vasomotor or rhinitis medicamentosa).
• An anatomic abnormality that interferes with assessment of nasal function. - History of clinically significant recurrent sinusitis or chronic sinusitis. - Clinically significant (as determined by the Investigator) cardiovascular, hepatic, neurologic, psychiatric, endocrine, or other significant systemic disease that makes implementation of the protocol jeopardizing to the safety of the subject.
• A need for use of antihistamines or corticosteroids on a regular basis (systemic or topical).
• Currently taking monoamine oxidase (MAO) inhibitors.
• Taken any systemic corticosteroids, immunomodulators, or immune suppressive medications within four weeks prior to Visit 1.
• Taken any antihistamine within seven days prior to Visit 1 skin testing.
• Known current alcohol or drug abuse.
• Current participation in another clinical study involving an experimental treatment, or participation in such a study within 30 days prior to study entry. - History of generalized anaphylaxis requiring medical attention.
• Clinically significant abnormality of screening blood chemistry, hematology, or urinalysis.