Background: Antibiotics are the first line treatment for bacterial infections; however, overuse and inappropriate prescribing has made antibiotics less effective with increased antimicrobial resistance. Unconfirmed reported antibiotic allergy labels create a significant barrier to optimal antimicrobial stewardship in healthcare, with clinical and economic implications.

Objective: A systematic review was conducted to summarise the impact of patient-reported antibiotic allergy on clinical outcomes and various strategies that have been employed to effectively assess and remove these allergy labels, improving patient care. Methods: The review was undertaken using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A critical appraisal was conducted on all studies and a narrative synthesis was performed to identify themes.

Results: Four themes emerged, the prevalence of antibiotic allergy, impact of antibiotic allergy on antimicrobial prescribing, impact of antibiotic allergy on clinical outcomes and delabeling strategies to improve clinical outcomes. Of the 32 studies, including 1,089,675 participants, the prevalence of reported antibiotic allergy was between 5-35%. Patients with a reported antibiotic allergy, had poorer concordance with prescribing guidelines in 30-60% of cases, with a higher use of alternatives such as quinolone, tetracycline, macrolide, lincosamide and carbapenem and lower use of beta-lactam antibiotics. Antibiotic allergy delabeling was identified as an intervention and recommendation to advance the state of the science.

Conclusion: There is substantial evidence within the literature that antibiotic allergy labels significantly impact on patient clinical outcomes and a consensus that systematic assessment of reported antibiotic allergies, commonly referred to as "delabeling", improves the clinical management of patients.