A Trial Evaluating Tolerability of Grazax Treatment in Combination With Antihistamine

Inclusion Criteria: * Male or female 18-65 years of age * Written informed consent obtained before any clinical trial procedures are performed * A clinical history of grass pollen induced allergic rhinoconjunctivitis of two years or more requiring treatment during the grass pollen season * Reporting of treatment related allergic AEs (local reactions in mouth and throat) after intake of Grazax at screening (visit 1) * Positive skin prick test (SPT) response (wheal diameter ≥ 3 mm larger than the negative control with a flare) to Phleum pratense * Female subjects had to be non-pregnant and non-lactating. * Subject willing and able to comply with the protocol Exclusion Criteria: * Uncontrolled asthma in the past 12 months * FEV1 \< 70% of predicted value (calculated according to ECCS (20)) * A clinical history of symptomatic seasonal allergic rhinitis and/or asthma due to another allergen which might have caused symptoms during the conduct of this trial * A clinical history of significant symptomatic perennial rhinitis or allergic rhinitis/asthma caused by an allergen to which the subject was regularly exposed * At randomization, current symptoms of, or treatment for, upper respiratory tract infection, acute sinusitis, acute otitis media or other relevant infectious process (serous otitis media is not an exclusion criterion) * History of emergency visit or admission for asthma in the previous 12 months * Use of an investigational drug within 30 days prior to screening * History of anaphylaxis, including anaphylactic food allergy, insect venom anaphylaxis, exercise anaphylaxis or drug induced anaphylaxis * History of chronic urticaria within the last year * History of angioedema * Any of the following underlying conditions known or suspected to be present: * Cystic fibrosis, malignancy, insulin-dependent diabetes, malabsorption or malnutrition, renal, or hepatic insufficiency, chronic infection, drug dependency or alcoholism * Any evidence of disease making implementation of the protocol or interpretation of the protocol results difficult or jeopardising the safety of the subject (e.g. clinically significant cardiovascular, serious immunopathologic, immunodeficiency whether acquired or not, hepatic, neurologic, psychiatric and ongoing long term treatment with tranquilizer or psychoactive drugs, endocrine, or other major systemic disease or malignancies (including auto-immune diseases, tuberculosis and HIV)). * Immunosuppressive treatment * History of allergy, hypersensitivity or intolerance to IMPs (except for Phleum pratense) or desloratadine * Unlikely to be able to complete the trial, for any reason, or likely to travel for extended periods of time during the trial, which in the opinion of the investigator will compromise the data * Being the investigator, trial staff or their immediate families, defined as the investigator's/staff's spouse, parent, child, grandparent, or grandchild or being the 2nd member of a family (living in the same household) * Use of any prohibited drugs