Twenty Years' Experience with Anaphylaxis-Like Reactions to Local Anesthetics: Genuine Allergy is Rare.

Abstract

Anaphylaxis-like reactions occur within minutes after the application of local anesthetics (LA), most commonly during dental interventions. Impressive symptoms including respiratory distress or loss of consciousness frequently give rise to a suspicion of allergy and may prompt patients and treating physicians to refuse future LA injections. Nonallergic mechanisms are responsible for the majority of LA-induced immediate-type reactions. In view of the preponderance of nonallergic reactions, the question arises whether genuine LA allergy may be missed during routine testing procedures. We retrospectively evaluated clinical data and test results from patients referred to our allergy clinic within the past 20 years for diagnostic workup of LA-induced immediate-type reactions. Of 402 evaluated patients, 29 had an episode of acute urticaria within 30 minutes after LA injections, and the remaining 373 had a history of mainly subjective cutaneous, respiratory, cardiovascular, and neurological complaints. Of the patients reporting urticaria with or without angioedema, 14 were diagnosed with a spontaneous episode of urticaria, 13 had allergic or nonallergic reactions to other agents, and 2 had IgE-mediated LA allergy. LA allergy was definitely excluded by 771 subcutaneous provocation tests with skin test negative LA, thereby demonstrating the high predictive value of negative intradermal testing. Skin testing and provocative LA challenge are useful to exclude LA allergy, and this testing procedure seems to be appropriate to identify the extremely rare cases with IgE-mediated LA allergy.