IGHE and Allergy: The Partners HealthCare System (PHS) guideline for inpatients with β-lactam allergy histories is an antibiotic stewardship tool that includes penicillin and cephalosporin hypersensitivity pathways that direct PST when institutionally available and needed (ie, patients reporting IgE-mediated allergy symptoms to a penicillin who require a penicillin or cross-reactive cephalosporin), but it encourages direct full-dose and test-dose (ie, standardized 2-step graded) drug challenges.