Impact of a Pharmacist-Driven Penicillin Allergy De-Labeling Service (PADLS) on Hospitalized Patients

Penicillin (PCN) allergies are frequently reported despite a true prevalence of less than 1%, leading to unnecessary avoidance of beta-lactams, broader antimicrobial use, and increased healthcare costs. Pharmacist-driven de-labeling programs offer a strategy to improve antimicrobial stewardship. This single-center, retrospective study evaluated hospitalized adults with a documented PCN allergy and screened by the pharmacist-driven penicillin allergy de-labeling service (PADLS) between 16 January and 26 June 2025. Patients were categorized into a screened cohort and a Full Allergy Reconciliation (FAR) cohort if interviewed using PEN-FAST. Eligible patients underwent direct oral challenge (DOC), penicillin skin testing (PST) plus DOC, or direct de-labeling based on PEN-FAST scoring. Sixty-three patients were screened, and 32 (50.8%) underwent full reconciliation. Among FAR patients, the median PEN-FAST score was 0, and 25 (78.1%) underwent DOC. De-labeling was successful in 28 FAR patients (87.5%). One patient (4%) experienced a mild reaction. Allergy field updates occurred in 69.8% of screened and 96.9% of FAR patients. Antibiotic optimization occurred in 12 FAR patients, saving 78 days of therapy. Estimated cost savings totaled $37,632. PADLS effectively and safely de-labeled PCN allergies, resulting in improved antimicrobial selection, and could generate cost savings, supporting broader implementation of pharmacist-led allergy stewardship programs.