A statement on cefazolin immediate hypersensitivity: data from a large database, and focus on the cross‐reactivities

Summary Background More perioperative cefazolin use has resulted in an increased risk of cefazolin‐associated reactions. Objective The aim of this article is to study immediate reactions to cefazolin and attempt to determine possible allergic cross‐reactivity with other ß‐lactams using data from the Drug Allergy and Hypersensitivity Database (DAHD). Methods All 25 cefazolin‐associated reactions in the DAHD were reviewed. The cases identified were then investigated according to the European Network for Drug Allergy (ENDA) recommendations by skin testing and challenges. Results A total of 10 individuals with proven IgE‐mediated cefazolin hypersensitivity were identified between January 1999 and July 2009. All the index reactions were compatible with an acute IgE‐mediated process, six with anaphylaxis, two with systemic allergic reactions without hypotension, and two with urticaria/angioedema. Cefazolin skin tests were positive in seven individuals and cefazolin challenges were positive in three more individuals. In the eight cefazolin allergic patients who had challenges with other ß‐lactams, there was no positive reaction noted. Conclusion and Clinical Relevance In this cohort of patients with IgE‐mediated reactions to cefazolin, a majority tolerated amoxicillin and several patients tolerated other cephalosporins. This implies that the R1 side‐chain may play an essential role in IgE‐mediated reactions to cefazolin. No clear rule to predict cross‐reactivity with other ß‐lactams could be determined. More research on IgE‐mediated hypersensitivity to cefazolin and other cephalosporins is needed.