Safety and Efficacy Study With Allergen Extracts of House Dust Mites for Specific Sublingual Immunotherapy

Inclusion Criteria: * Positive history of perennial allergic rhinitis * Positive screening skin prick test (wheal diameter \> 3 mm) * Compliance and ability of the patient to complete a Diary Card for self-evaluating of the symptoms and antisymptomatic medication * Signed and dated patient´s Informed Consent, Exclusion Criteria: * Previous immunotherapy with allergen extracts within the last 3 years, * Simultaneous participation in other clinical trials, * Other reasons contra-indicating an inclusion into the trial according to the investigator´s estimation (e.g. poor compliance), * Auto-immune disorders, * Severe chronic inflammatory diseases, * Malignancy, * Alcohol abuse, * Existing or intended pregnancy, lactation and/or lack of adequate contraceptive protection, * Treatment with beta-blockers (incl. local application) and/or other contra-indicated drugs.