Background: 15% of hospitalized patients have a documented penicillin (PCN) allergy. However, fewer than 1% of those patients have a true IgE-mediated reaction that necessitates avoidance of beta-lactam antibiotics. Labeling a patient with a PCN allergy is associated with prescribing non beta-lactam (NBL) broad spectrum antibiotics and increased adverse outcomes. Patients with a documented PCN [...]