Inclusion Criteria:

• Male or female Chinese subjects aged 12-65 years
• A clinical history of HDM AR/C (Allergic rhinitis/rhinoconjunctivitis) (with or without asthma) and with allergic rhinitis symptoms despite having received allergy pharmacotherapy during the previous year prior to screening
• Have a certain level of AR (Allergic rhinitis) symptoms on at least 8 of the last 14 days of the baseline period
• Use symptomatic medication for treatment of HDM allergic rhinitis during at least 8 of the last 14 days of the baseline period
• Positive skin prick test (SPT) and IgE (Immunoglobulin E) to D. pteronyssinus or D. farinae at screening
• Lung function ≥ 70% of predicted value

Exclusion Criteria:

• Sensitised and regularly exposed to perennial allergens
• Any nasal or pharyngeal condition that could interfere with the safety or efficacy evaluation
• Asthma requiring treatment with high dose of inhaled corticosteroid
• A relevant history of systemic allergic reaction