Inclusion Criteria:

• Subjects must be outpatients between the ages of 18 and 75 years, inclusive, and of either sex.
• Subjects must have moderate to severe persistent allergic rhinitis with a history of intermittent asthma of at least 2 years and actual asthma (symptoms in the last 4 weeks).
• Subjects must be clinically symptomatic at the randomization visit.
• A positive (wheal diameter >3 mm) skin prick test (SPT) and/or CAP-RAST (class II or higher) performed in the 6 months prior to the start of the trial are required for at least house dust mite and one pollen allergen (grass or Parietaria, IgE level >3.5 U/mL). The SPTs should have been performed with a standard panel of allergens common in the region, including the following: dust mites, grasses, parietaria, birch, alder, olive, cypress, cat, dog, Alternaria, and Aspergillus.
• Female subjects of childbearing potential (including women who are less than 1 year postmenopausal and women who will be sexually active during the study) must agree to use a medically accepted method of contraception or be surgically sterilized prior to screening, while receiving protocol-specified medication, and for 30 days after stopping the medication. Women who are postmenopausal for >1 year (i.e., women who have experienced 12 consecutive months of amenorrhea) will be exempted from the use of contraception during the study.
• Female subjects of childbearing potential must have a negative urine pregnancy test at screening.

Exclusion Criteria:

• Subject is a female who is pregnant or nursing, or who intends to become pregnant or nursing during the study or within 12 months after study completion.
• Subject has anatomical abnormalities of the nose (turbinate hypertrophy, septal deviation, polyps) that would interfere with nasal airflow.
• Subject has acute or chronic sinusitis currently being treated with antibiotics and/or topical or oral decongestants.
• Subject has rhinitis medicamentosa.
• Subject has evidence of persistent asthma, or asthma with daytime and night-time symptoms not controlled by short-acting beta2-adrenoceptor agonists.
• Subjects with asthma who require chronic use of inhaled or systemic corticosteroids.
• Subjects who have had an upper respiratory tract or sinus infection that requires antibiotic therapy and have not had at least a 14 day wash-out period prior to the run-in period, or who have had a viral upper respiratory infection within 7 days prior to screening.
• Subject has a dependence on nasal, oral or ocular decongestants, nasal topical antihistamines, or nasal steroids.
• Subject is currently undergoing a progressive course of immunotherapy (hyposensitization). Subjects on a regular maintenance schedule prior to the screening visit and wish to remain on this schedule during the study are eligible for study inclusion; however, subject may not receive hyposensitization treatment within 24 hours prior to any study visit.
• Subject has been diagnosed of cancer within the past 5 years (except for successfully treated basal and squamous cell carcinomas).
• Subject has a concomitant medical problem that may interfere with participation in the study; e.g., repeated migraine episodes, uncontrolled convulsive disorders.
• Subject has any of the following clinical conditions: active or quiescent tuberculosis infection of the respiratory tract, untreated fungal, bacterial, systemic viral infections or ocular herpes simplex.
• Subject smokes, or is an ex-smoker who has smoked within the previous 6 months.