Analysis of an unusual cluster of systemic reactions to subcutaneous specific immunotherapy with respiratory allergens in one allergy center.

Systemic reactions to subcutaneous immunotherapy occur despite all necessary precautions and experienced staff and should prompt a search for causative factors. We present an analysis of 11 reactions, 8 of them within a short period. The patients and reactions were evaluated regarding extract errors (composition, concentration), dosing errors, ignored contraindications to specific subcutaneous immunotherapy, introductions versus maintenance phase and accidental intravascular injection. No single or common cause could be identified. Statistical analysis suggests that exceptional clusters of systemic reactions such as these may be just random cumulations without identifiable cause.