 - Use of followings medications are not allowed throughout the study: Short-acting antihistamines, including ocular preparations and antihistamines contained in anti-cold medicine, insomnia or antalgic; Oral or inhaled anticholinergics; Oral or intranasal decongestants; Oral or intranasal antileukotrienes; Oral or inhaled long-acting beta2 agonists; Chinese traditional medicines that have potential effect to AR; Liquorice preparation; Medications that significantly inhibit the CYP3A4, including ritonavir and ketoconazole; tricyclic antidepressants; long-acting antihistamines eg. desloratadine, fexofenadine, cetirizine and loratadine taken as rescue medication; Intranasal antihistamines; or Intranasal or ocular cromolyh; Intranasal corticosteroids includes: Inhaled, oral, intramuscular, intravenous, ocular andor dermatological corticosteroid with the exception of hydrocortisone creamointment, 1 or less and Immunosuppressive medications; Subcutaneous omalizumab. 