The Penicillin Allergy Puzzle: Who’s Really Allergic?

“Most penicillin allergy labels are not indicative of any meaningful penicillin allergic reaction, and the vast majority can be de-labelled with direct oral challenges of amoxicillin."  — Dr. Kimberly Blumenthal

Penicillin allergy is one of the most commonly reported drug allergies—but here’s the twist: most people who carry this label aren’t actually allergic. So how did we get here, and what can be done to fix it?

On this episode, Dr. Mariam Hanna sits down with Dr. Kimberly Blumenthal, an allergist, immunologist, and clinical researcher at Massachusetts General Hospital, and an associate professor at Harvard Medical School. Dr. Blumenthal is internationally recognized for her work on penicillin allergy and the real-world impact of unnecessary labels on patient care, antibiotic resistance, and health equity.

We cover:

• Why penicillin allergy is so commonly (and incorrectly) diagnosed
• How de-labelling can improve antibiotic stewardship and patient outcomes
• Risk stratification: who needs testing, who can go straight to a challenge, and who should avoid penicillin?
• The role of allergists in leading the charge on de-labelling efforts
• Special populations, including pregnant patients, children with serum sickness-like reactions, and marginalized communities with less access to allergy care
• International practices that complicate the picture—like routine penicillin pre-screening in some countries

With the vast majority of penicillin allergy labels being inaccurate, this episode highlights why it's time to stop assuming and start testing.

Visit the Canadian Society of Allergy and Clinical Immunology

Find an allergist using our helpful tool

Find Dr. Hanna on X, previously Twitter, @PedsAllergyDoc or CSACI @CSACI_ca

The Allergist is produced for CSACI by PodCraft Productions