For most patients with penicillin allergy in their records, it is a safe way to delabel.

Several recent studies have addressed overuse of penicillin­-allergy labelling. Although 10% of hospitalised patients have penicillin allergy listed in their records, fewer than 10% of those patients have true allergies. Use of more expensive and broader­-spectrum antibiotics is associated with longer and more expensive hospital stays and more side effects, nosocomial infections and resistant organisms.

In a systematic review of 56 studies, researchers examined the safety of direct penicillin challenges (without preceding skin tests) for delabelling patients without true allergies. Among more than 9000 patients in these studies, 438 experienced reactions (3.5%), with only five reactions classified as severe: three episodes of anaphylaxis, one delayed rash with fever and one kidney injury. No fatalities were reported.

Comment: We have far more patients who should have their penicillin allergy delabelled than we have allergists to perform these challenges. Primary care clinicians and hospitalists can do this easily by giving one dose of amoxicillin (500 mg) and watching the patient for one to two hours; intramuscular epinephrine and oral antihistamines must be available, but are seldom needed. The PENFAST score is a good tool to help decide which patients can undergo direct oral challenge safely (NEJM JW Gen Med 1 Aug 2023 and JAMA Intern Med 2023; 183: 883­-885). In general, if a patient has a history of severe immediate reaction (angioedema or anaphylaxis), a recent urticarial reaction (within five years) or any severe delayed reaction (e.g. Stevens–Johnson syndrome, serum sickness, drug reaction with eosinophilia, drug-­induced cytopenia, organ injury), I would refer to an allergist for evaluation.

David J. Amrol, MD, Associate Professor of Clinical Internal Medicine, Director of the Division of Allergy and Immunology, University of South Carolina School of Medicine, Columbia, USA.

Blumenthal KG, et al. Reaction risk to direct penicillin challenges: a systematic review and meta-analysis. JAMA Intern Med 2024;184:1374-1383.

This summary is taken from the following Journal Watch titles: General Medicine, Ambulatory Medicine, Hospital Medicine.