A Comparison of Aerius Continuous Treatment Versus Aerius PRN for Chronic Idiopathic Urticaria (Study P03147)

Inclusion Criteria:

• Subjects must demonstrate their willingness to participate in the study and complywith its procedures by signing a written informed consent.

• Subjects must be >= 18 years of age

• Women of childbearing potential must have a negative urine pregnancy test at Visit 1 (Day 1) and must be using an acceptable method of birth control during the study.

• Subjects must be in general good health; ie, they must be free of any clinicallysignificant disease (other than CIU) that would interfere with study evaluations.

• Subjects must understand and be able to adhere to visit schedules, and agree tocomplete the questionnaires and a diary.

• Subjects must have at least a 6-week history of CIU (pruritus and hives) prior toVisit 1.

Exclusion Criteria:

• Women who are pregnant or nursing.

• Subjects who used any investigational drug in the last 30 days prior to Visit 1

• Subjects with asthma requiring chronic use of inhaled or systemic corticosteroids.

• Subjects who have been treated with any investigational antibodies for asthma orallergic rhinitis in the 90 days prior to Baseline.

• Subjects who have been treated with intra-muscular or intra-articularcorticosteroids in the 90 days prior to Baseline.

• Subjects with urticaria that is primarily due to physical urticaria or other knownetiology, except dermographism.

• Subjects treated by immunosuppressive drugs.

• Subjects who have been hospitalized (including an emergency department visit)because of deterioration in their CIU within 3 months prior to Visit 1.

• Subjects with a history of hypersensitivity to desloratadine or any of itsexcipients.

• Subjects previously randomized into this study.

• Subjects who have any clinically significant metabolic, cardiovascular,immunological, neurological, hematological, gastrointestinal, cerebrovascular, orrespiratory disease, or any other disorder which, in the judgment of theinvestigator, may interfere with the study evaluations or affect subject safety.

• Subjects with a history of psychosis, antagonistic personality, poor motivation,hypochondriasis, or any other emotional or intellectual problems that are likely tolimit the validity of consent to participate in the study.

• Subjects with a history of noncompliance with medications or treatment protocols.