Response to sublingual immunotherapy with grass pollen extract: monotherapy versus combination in a multiallergen extract.

Background: To date, there have been no randomized, double-blind studies showing the effectiveness of sublingual immunotherapy with multiple allergens.

Objective: The purpose of this study was to examine whether the efficacy of sublingual immunotherapy (SLIT) with standardized timothy extract was reduced by combination with other allergen extracts.

Methods: A single-center, randomized, double-blind, placebo-controlled trial with SLIT was conducted.