Premedication with antihistamines may enhance efficacy of specific-allergen immunotherapy

Antihistamine premedication has been used to increase safety of specific-allergen immunotherapy. Its influence on the efficacy of this treatment has not been studied so far.

The goal was to analyze the influence of antihistamine premedication on long-term efficacy of specific-allergen immunotherapy.

Patients included in a double-blind, placebo controlled trial who received premedication with terfenadine or placebo during initial rush immunotherapy with honeybee venom in 1988/1989 were assessed in a retrospective analysis for the long-term protective effect, as indicated by the tolerance of a bee sting challenge or field sting during immunotherapy.

Of the 52 patients who had participated in the 1988/1989 trial, 47 could be reassessed after an average of 3 years. Of these, 45 were still receiving bee venom immunotherapy. A total of 41 patients were stung by bees while receiving immunotherapy (20 of the terfenadine-premedicated group and 21 of the placebo-premedicated group), 17 with in-field stings and 24 with in-hospital sting challenge. Six (29%) of the patients receiving placebo had a mild-to-moderate systemic allergic reaction, whereas none of the patients receiving terfenadine reacted to the bee sting (P =.012).

These results indicate that antihistamine premedication during the initial phase of specific-allergen immunotherapy may enhance the efficacy of this treatment.