Anaphylactic reactions during immunotherapy.

Subcutaneous immunotherapy (IT) with aeroallergen extracts is venerable treatment modality. The major risk associated with IT with commercial aeroallergen extracts is the uncommon occurrence of severe near-fatal or fatal anaphylaxis after injections. The objectives of this article are to review the reported incidences of severe anaphylaxis (near-fatal reactions and fatal reactions), define factors contributing to these events, and identify preventive measures that are likely to reduce or eliminate future fatal and near-fatal anaphylactic events. As with any treatment, anticipated benefits attributed to IT must be weighed against its potential risks.