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

BACKGROUND: 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.

OBJECTIVE: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.