The local and systemic side-effects of venom and inhaled-allergen subcutaneous immunotherapy
BACKGROUND: Although immunotherapy is effective in allergic rhinitis, conjunctivitis, asthma and stinging insect hypersensitivity, it carries a risk of anaphylactic reactions. METHODS: In a 4-year retrospective survey, we investigated 1257 adult patients who had received venom or inhaled-allergen subcutaneous immunotherapy. The dose-increase phase was performed as the 2-day rush protocol for venom immunotherapy and the 6-week protocol for inhaled-allergen immunotherapy. RESULTS: A total of 904 patients received venom immunotherapy and 353 patients inhaled-allergen immunotherapy. The prevalence of systemic reactions was 13.6%. The frequency of systemic reactions was higher during the maintenance phase than in the dose-increase phase (9.6% vs. 5.9%) and was highest in both phases of treatment with honeybee venom (P < 0.001). The majority of systemic reactions were mild. Five (0.4%) patients had reaction with a fall of blood pressure and were treated with adrenaline. There was no fatal outcome. The systemic side-effects during the dose-increase phase of venom immunotherapy occurred at a median dose of 46 μg (range 2–100 μg). Large local reactions occurred in 13.9% of patients without any significant difference between the allergens. CONCLUSIONS: We have shown that systemic reactions are not rare even during maintenance phase in patients with a well tolerated dose-increase phase of treatment. The most prominent risk factor for systemic reactions was immunotherapy with honeybee extract.