Venom immunotherapy: clinical efficacy, safety and contraindications.

Venom-specific immunotherapy (VIT) is considered for the treatment of patients with IgE-mediated systemic allergic reactions (SARs) after developing a Hymenoptera venom allergy. Tolerance is achieved in a majority of patients after only a few days or even hours of rush immunotherapy. After VIT discontinuation, the allergy returns in up to 15% of patients. During VIT, the majority of patients have local reactions at the site of venom injections. SARs to VIT are much more frequent in honeybee-treated patients than in wasp-treated patients. Increased baseline serum tryptase and increased allergen-specific sensitivity of basophils are other factors that might be associated with systemic reactions (SRs) during VIT. Severe SRs occur mainly during the build-up phase but can also occur in the maintenance phase of the VIT, even in patients with a well-tolerated dose-increase phase. Pre-treatment with humanized anti-IgE antibodies (omalizumab) is effective in patients with repeated SARs; however, this use of omalizumab is off-label. In highly exposed patients with a history of very severe reactions, there are virtually no absolute contraindications for VIT.