Is Levocetirizine Less Sedating Than Cetirizine?

Inclusion Criteria:

• patients 18 years of age or older

• patients with perennial allergic rhinitis sensitized (positive RAST within the last 3years or wheal greater than or equal to 3 mm within the last 3 years) to either:

• dust mite

• cat (if they own an indoor cat)

• dog (if they own an indoor dog)

• will allow for sensitization to tree, grass, or weed pollen, cockroach, or mold

• history of reported sedation/somnolence when taking cetirizine

• patient must have taken cetirizine for at least 1 week prior to discontinuing it

• patients must have either tolerated levocetirizine in the past or have never triedlevocetirizine.

Exclusion Criteria:

• chronic urticaria requiring ongoing antihistamine or steroid treatment

• atopic dermatitis requiring ongoing antihistamine or steroid treatment

• URI or sinus infection during the 2 weeks preceding the beginning of the study

• vasomotor (non-allergic) or irritant rhinitis

• afrin use

• elderly or over 77 years of age (could affect creatinine clearance) or chronic renalinsufficiency

• patients who have not tolerated levocetirizine in the past due to sedation.

• taking other prescription or over the counter antihistamines and unwilling to stopthem during the study

• the presence of a sleep disorder such as sleep apnea or narcolepsy

• the use of as needed sleeping aid medication

• the presence of other chronic medical conditions which in the opinion of theinvestigator would prevent the subject from being able to participate effectively