Pemphigoid associated with quinolone antibiotics: a real-world pharmacovigilance study of the FDA adverse event reporting system and literature-based evidence.

Objective: Pemphigoid is a rare autoimmune disorder that may be drug-induced. This study aims to investigate the potential association between pemphigoid and quinolone using the FDA Adverse Event Reporting System (FAERS) database. Methods: FAERS reports were analyzed using disproportionality methods, including the reporting odds ratio (ROR), proportional reporting ratio (PRR), and Bayesian confidence propagation neural network (BCPNN). Subgroup analyses were performed by age, sex, and reporter type. An interaction analysis integrating published literature on quinolone-associated pemphigoid (QAP) was conducted to assess consistency in reporting disproportionality, demographics, latency, and clinical outcomes. Results: A total of 183 reports of quinolone-associated pemphigoid were identified. Ofloxacin accounted for the largest proportion of cases (47.0%), followed by ciprofloxacin (26.2%) and levofloxacin (23.0%). Significant disproportionality signals were detected for ofloxacin (ROR = 2.75), ciprofloxacin (ROR = 2.31), levofloxacin (ROR = 2.53). A remarkably high signal was also noted for norfloxacin (ROR = 25.14); however, this requires extremely cautious interpretation due to the very small number of cases (n=3). Most pemphigoid events occurred within 30 days of quinolone initiation, indicating a short latency pattern consistent with immune-mediated blistering reactions. Subgroup analyses revealed differential reporting patterns by age and sex. Furthermore, the interaction analysis with published literature corroborated the FAERS findings, demonstrating consistent patterns in demographic susceptibility (predominantly elderly and female), short latency, and clinical outcomes. Conclusions: This study demonstrates that several quinolone antibiotics are associated with an increased reporting frequency of pemphigoid in FAERS. The early onset and consistency across data sources support quinolone-associated pemphigoid as a clinically meaningful immune-related adverse drug reaction, underscoring the importance of early clinical recognition and monitoring during the initial phase of quinolone therapy.