Bérot V, Gener G, Ingen-Housz-Oro S, et al. - Researchers examined patients with non-immediate cutaneous adverse drug reaction (non-immediate CADR) managed in a dermatology reference center of toxic bullous and severe CADRs to assess cross-reactivity beyond beta-lactam antibiotics (BL). In this retrospective single-center study, 56 patients were included, among whom 46 amoxicillin-suspected were and seven cephalosporin-suspected. Severe CADR was reported in 29 patients, and non-immediate maculopapular exanthema (MPE) was reported in 27. Positive tests were reported in 22 (18 for AS and four for CS). Among the 18 positive amoxicillin-suspected, 10 (55.6%) displayed cross-reactivity with one or more other BL: 9 (50%) with another penicillin and 3 (16.5%) with a non-aminocephalosporin. Cross-reactivity with aztreonam or carbapenems was not observed with any of the amoxicillin- or cephalosporin-suspected patients. Based on these findings, they suggest performing a large allergologic exploration following a suspected BL-induced non-immediate CADR, to confirm the diagnosis and evaluate cross-reactivity. They observed cross-reactivity among penicillins frequently encouraging stopping this whole family and testing cephalosporins, aztreonam, and carbapenems for which cross-allergies are rarer.