The objective of this trial is to evaluate the clinical effectiveness of the administration of a depigmented and polymerized allergen extract of Phleum pratense in the rhinoconjunctivitis and/or asthma of slight or moderate intensity, due to allergy to grass pollen.

Immunotherapy is a specific treatment for allergic diseases. Unlike conventional pharmacological treatment, immunotherapy is the only treatment that could modify the natural course of allergic disease. This is a prospective double-blind placebo controlled study with three arms of treatment: placebo and two active (one of the active arms will receive a dose that is 10x the dose of the other arm).

Inclusion Criteria:

• Positive clinical history of allergy to Phleum pratense
• Patients of both gender aged from 12 up to 50 years.
• Positive prick test to Phleum pratense allergen extracts
• Specific IgE to Phleum pratense
• Positive clinical history of allergic rhinoconjunctivitis and/or asthma
• Written informed consent.

Exclusion Criteria:

• Use of immunotherapy during the last four years.
• Any contraindication for the use of immunotherapy in accordance with European Allergy and Clinical Immunology Immunotherapy Subcommittee criteria:
• Treatment with ß-blockers
• Coexistence of immunopathological diseases (e.g. of the liver, kidney, the nervous system, thyroid gland, rheumatic diseases) in which autoimmune mechanisms play a role
• Patients suffering from immune deficiencies
• Patients with serious psychiatric / psychological disturbances
• In addition, the following was considered as exclusion criteria:
• Pregnant or/ in lactation patients
• Patients aspirin intolerance