# Incidence of fidaxomicin allergy in patients with macrolide allergies: a large database analysis

## TL;DR

The study finds that patients with macrolide allergies have a higher risk of developing an allergy to fidaxomicin, with varying odds depending on the specific macrolide.

## Contribution

The study quantifies the increased risk of fidaxomicin allergy in patients with specific macrolide allergies using large database analysis.

## Key findings

- Patients with azithromycin allergy had 2.31 times higher odds of fidaxomicin allergy.
- Anaphylaxis and angioedema risk was highest within one year of a non-fidaxomicin macrolide allergy.

## Abstract

Fidaxomicin may exhibit cross-reactivity in patients with known macrolide allergies. In this analysis, compared to patients without macrolide allergies, the odds of fidaxomicin allergy were 2.31, 8.37, and 1.58 times higher in patients with azithromycin, clarithromycin, and erythromycin allergies, respectively; the absolute risk of fidaxomicin allergy was 0.033, 0.01, and 0.039 in patients with azithromycin, clarithromycin, and erythromycin allergies, respectively. The highest risk of anaphylaxis and angioedema was observed within 1 year of a non-fidaxomicin macrolide allergy.