To evaluate the efficacy of an extract of Dermatophagoides pteronyssinus versus placebo in the treatment of local allergic rhinitis. The primary efficacy endpoint is the reduction in symptom scores and medication use in the active group compared to placebo.

The influence of treatment in "in vitro" and "in vivo" objective parameters was also assessed.

Inclusion Criteria:

• Prior to study specific examinations the patient has to give his/her written informed consent.
• Local allergic rhinitis induced by Dermatophagoides pteronyssinus (DP).
• Age: 18-55.
• Negative skin prick-test to DP
• Positive nasal allergen provocation test to DP (NAPT-DP) and/or nasal specific IgE (sIgE) to DP>0.35 kU/L
• If applicable negative urine pregnancy test and willingness to use effective form of contraception for the duration of involvement in the study.

Exclusion Criteria:

• Severe immunopathological or immunodeficiencies diseases.
• Treatment with beta-blockers, even when administered topically
• Severe psychological disorders
• Severe Atopic Dermatitis
• FEV1 <70% predicted after appropriate pharmacological treatment
• History of hypersensitivity or intolerance to excipients and / or trial medication or other medication to be used for protocol
• Inability to adequately perform diagnostic tests or treatment
• Awareness of other inhaled allergens (perennial or seasonal) clinically relevant to the subject and that may interfere with the response evaluation
• Treatment with immunotherapy in the 5 years prior to his inclusion in the study