Objective: The purpose of this randomized, double-blind, placebo-controlled study was to evaluate the clinical efficacy and tolerance of once-daily sublingual immunotherapy without updosing. Reduction in symptoms and medication use was the primary endpoint.

Methods: One hundred fi ve patients with rhinitis and/or asthma due to grass and olive sensitization were randomized to be treated with placebo or active sublingual immunotherapy with the SLITone grass mix plus olive pollen extract for 6 months before the 2005 pollen season. Patients recorded symptoms and medication intake for 8 weeks during the pollen seasons in 2004 (n = 37) and 2005 (n = 85).

Results: Allergic symptoms were significantly decreased in the active immunotherapy group (P = .004) but not in the placebo group. There were no differences in scores between groups during the 2005 pollen season. Subjective assessments on a visual analog scale and a quality-of-life questionnaire indicated an improvement in actively treated patients with signifi cant differences in both symptoms and medication use (P = .006). The rate of systemic adverse reactions was comparable in the 2 groups. No anaphylactic or severe adverse reactions were reported. Local adverse reactions, which were more common in the active immunotherapy group, were mostly immediate,
were limited to the lips and mouth, and did not require treatment.

Conclusion: Once-daily sublingual immunotherapy without updosing was well tolerated. The actively treated patients showed a significant reduction in symptom and medication scores and an improvement in their quality of life although there were no significant differences between the groups probably due to the low allergen season in which the study was evaluated.

Key words: Olea species. Grasses. Sublingual immunotherapy. Rhinitis. Allergens. Clinical efficacy. Tolerance.