Cosalin® Monotherapy Versus Cosalin® and Xarlin® Combination Therapy

Inclusion Criteria: 1. Male and female volunteer more than 18 years old and less than 66 years old. 2. A volunteer who is informed about this study and sign the informed consent. 3. A volunteer who is diagnosed perennial allergic rhinitis greater than grade3 at visit 1(screening visit) by allergy skin test or serum IgE antibody assay in 24 months. 4. A volunteer who has score 8 and more than 8 point 4 Total Symptom Score (4TSS - runny nose, nasal congestion, itchy nose, sneezing). Exclusion Criteria: 1. A volunteer who has hypersensitivity to Levocetirizine or Hydroxyzine 2. A volunteer who has hypersensitivity to Petasites hybridus leaves. 3. A volunteer who has anaphylaxis or hypersensitivity to allergy skin test. 4. A volunteer who has serious renal failure or liver failure. Ingestion of antibiotics during previous two weeks from Visit 1, cause of upper respiratory infection(include paranasal sinus). 5. A volunteer who need to use steroids cause of asthma. 6. A volunteer who is using steroids, decongestants, antihistamine. 7. A volunteer who has rhinitis medicamentosa. 8. A volunteer who has seasonal allergic rhinitis. 9. A volunteer who has Galactose intolerance, Lapp lactose deficiency, or glucose-galactose malabsorption genetic disorder . 10. A volunteer who is an alcoholic or a drug addict. 11. Women who are pregnant, breast-feeding, women who plan to get pregnant during the trial period, or do not use authorized contraceptive methods (e.g: sterilization, intrauterine device, combined use of oral contraceptives and barrier contraceptive, combined use of other hormone delivery systems and barrier contraceptive and combined use of contraceptive cream, jelly or foam and diaphragm or condom) in spite of possibility of pregnancy. 12. A volunteer who has experience to take test products in 1 month. 13. A volunteer who is concluded poor compliance or fail to follow medical instruction