Inclusion Criteria:  Birch pollen sensitized subjects  Moderate to severe allergic rhinitis to birch pollen allergen for at least two seasons according to their medical history Sensitization to Bet v 1 (Bet v 1 specific IgE: 3.5 kU/L or higher as specified by UniCAP-FEIA) CD203c or CD63 upregulation upon challenge with Bet v 1 in flow cytometric basophil activation tests (≥20% upregulation of CD63 or CD203c upon Bet v 1 stimulation in comparison with unstimulated controls as measured by flow cytometry) Willingness to follow the protocol. Written informed consent Standard healthcare insurance Subjects should be available during the entire study period  Exclusion Criteria:  Evidence of acute, chronic, malignant or general diseases- assessed by asking the patient (e.g. Did you suffer or are you currently suffering from any malignant or generalised disease? Did you suffer or are you currently suffering from any chronic disease? Did you have any acute disease in the past two weeks?). A History of anaphylaxis. Utilization of leukotriene modifiers. Utilization of long-acting antihistamines. Chronic or intermittent use of oral, inhaled, intramuscular, intravenous, and potent topical corticosteroids. Nasal polyps, history of chronic sinusitis or considerable deviation of the nasal septum Rhinitis secondary to other causes. Contra-indications to skin prick testing, for example, skin irritation in the test area and urticaria factitia. Cardiovascular diseases or anti-hypertensive therapy and beta-blockers. Any disruption of coagulation system through medication or known clotting disorders Prophylactic aspirin therapy Chronic use of additional medications that would affect assessment and the results of the study (e.g., tricyclic antidepressants that block both H1 and H2 receptors) Pregnant or breastfeeding females. Actual disability that would influence subject's ability to participate in the study. History of mental illness, intellectual deficiency, drug or alcohol abuse Active asthma requiring treatment Birch Pollen allergen immunotherapy Arranged travel outside the study region for a substantial portion of study period.