Background: We identified a case of quinolone allergic hypersensitivity associated with quaternary ammonium (QA) sensitization, the allergic determinant of neuromuscular blocking agents (NMBAs). Concomitant sensitization to several chemically different drugs is rarely reported and raises the question of a nonfortuitous association., Objective: We evaluated a potential association between quinolone immediate allergic hypersensitivity and NMBA sensitization., Methods: QA-specific IgE detection was prospectively performed in 26 patients who presented an immediate hypersensitivity reaction to quinolones: 17 with a confirmed allergic hypersensitivity and 9 with allergic hypersensitivity not confirmed. We also included a control population of 88 outpatients without a history of quinolone or NMBA hypersensitivity. Patients with positive QA-specific IgE benefited from a NMBA allergologic workup., Results: The prevalence of positive QA-specific IgE was significantly higher in patients with quinolone allergic hypersensitivity (9/17, 53%) compared with patients with allergic hypersensitivity not confirmed (1/9, 11%) than in controls (3/88, 3.4%). In the quinolone allergic population, ofloxacin elicited inhibition of the 4 positive QA-specific IgE sera tested, in a dose-response manner. Among the 9 patients with positive QA-specific IgE, the QA sensitization (positivity of specific IgE) was confirmed by positive skin tests and/or basophil activation tests to at least 1 NMBA in 5 of the 7 tested patients., Conclusion: We report here the first documentation of a high prevalence of QA sensitization in patients with quinolone allergic hypersensitivity. These results suggest a new way for NMBA sensitization. It thus seems appropriate to investigate NMBA sensitization when quinolone allergic hypersensitivity is diagnosed., (Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)