TOPLINE

In a large database analysis, cross-drug reaction among fluoroquinolones (ciprofloxacin, levofloxacin, and moxifloxacin) was rare and only modestly raised subsequent reaction odds for some drug pairs, suggesting class-wide avoidance may be unwarranted and supporting drug challenge as a safe strategy in selected patients.

METHODOLOGY

• Researchers retrospectively analyzed a global healthcare database in September 2025, which included data from more than 250 healthcare organizations.
• A total of 96,966 patients with ciprofloxacin allergy labels, 64,863 with levofloxacin allergy labels, and 23,117 with moxifloxacin allergy labels were identified through codes linked to relevant antibiotic exposure.
• Patients who later received a different fluoroquinolone were assessed for potential cross-drug reactions using diagnosis codes.
• The assessed reactions included anaphylactic shock or angioedema within 1 day, pruritus or urticaria within 7 days, Stevens-Johnson syndrome or toxic epidermal necrolysis within 1 month, and drug reaction with eosinophilia and systemic symptoms within 2-6 weeks after second exposure.
• The primary outcomes were the prevalence of fluoroquinolone allergy labels and the frequency of potential cross-drug reactions to two distinct fluoroquinolones.

TAKEAWAY

• The prevalence of allergy labels was 1.1% for ciprofloxacin, 1.6% for levofloxacin, and 1.2% for moxifloxacin among patients who received these fluoroquinolones. 
• Potential cross-drug reaction frequencies ranged from 1.3% for levofloxacin followed by moxifloxacin to 2.9% for moxifloxacin followed by ciprofloxacin or levofloxacin; majority presented as pruritus or urticaria (88%), and most occurred within a year of the index fluoroquinolone allergy label (70%). 
• Compared with patients with no prior allergy, the odds of experiencing a potential cross-drug reaction were 18% higher among those who received ciprofloxacin and then levofloxacin, 12% higher among those who received levofloxacin and then ciprofloxacin, and 31% higher among those who received moxifloxacin and then ciprofloxacin (P < .05 for all).
• The odds of potential cross-drug reactions were not increased for certain drug pairs such as ciprofloxacin to moxifloxacin and levofloxacin to moxifloxacin.

IN PRACTICE

"These findings challenge the common practice of avoiding the entire class in patients with a single documented fluoroquinolone allergy label. Those with ciprofloxacin or levofloxacin allergy labels might be safe to use moxifloxacin, especially if the allergy label is more than 1 year old," the authors wrote.

SOURCE

Chia-Yu Chiu, with the University of Colorado, Aurora, was the corresponding author of the study, which was published online on August 21, as a Short Communication in the Journal of Allergy and Clinical Immunology: Global.

LIMITATIONS

Reactions were captured only by diagnostic codes; therefore, the specific clinical features and timing of each reaction could not be fully characterized. The underlying mechanism of allergic reactions could not be determined. Moreover, the database lacked details on drug dose and treatment setting, and it was unclear whether allergy labels reflected clinician confirmation or patient self-report.

DISCLOSURES

The authors reported no funding and declared having no conflicts of interest. 

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.