[Related systemic reactions to allergen immunotherapy in Monterrey, Mexico].

Background: Patients who receive allergen immunotherapy (IT) have a potential risk of systemic reactions, however such reactions are rare when IT administered properly. The frequency of systemic reactions (SR) due to conventional IT is less than 1%.

Objective: To determine the frequency of secondary SR to allergen IT, and to identify the possible factors involved in developing them.

Methods: A retrospective descriptive study that included 2.319 patients who received 14.600 allergen immunotherapy injections during the period from May 1, 2001 to April 30, 2002.

Results: Twelve patients had a SR (age 7 - 40 years), all of which occurred within the first 30 minutes after the IT. These were more frequent during the dose - increase phase (58%). The frequency of (RS) in relation to the number of injections was 1:1216, and regarding to the number of patients, 1:193. The clinical manifestations included bronchospasm 83%, urticaria 67%, gastrointestinal symptoms and hypotension 8.3%. The 58% had anaphylaxis and pulmonary or dermatological symptoms only in 33% and 8.3% respectively. The possible factors involved in the onset of SR were: sensitivity identified by large skin reactions in skin test (PC) 83%, uncontrolled asthma 50%, application of allergens IT during high pollination season 42%, inadequate immunotherapy scheme monitoring 17%.

Conclusions: The frequency of SR in this group of patients was low as that reported in other publications.