Safety of Azithromycin in Patients with Penicillin Allergy

Introduction to Azithromycin Safety

• Azithromycin is a macrolide antibiotic that has no structural relationship to penicillins and does not cross-react with beta-lactam antibiotics, making it safe for patients with penicillin allergy 1, 2, 3

Cross-Reactivity with Other Antibiotics

• Cephalosporins have variable cross-reactivity (2-16%) depending on side chain similarity to the culprit penicillin, whereas azithromycin does not 1, 2, 4
• Carbapenems and aztreonam (monobactams) can be given without prior testing for most penicillin allergies, similar to azithromycin 1, 2, 5

Clinical Considerations

• The severity of the original penicillin reaction and the timing of the reaction do not affect the safety of using azithromycin in patients with penicillin allergy 1, 2