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

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.