Are You Really Allergic to Penicillin? (Update)

Like tens of millions of people, Stephen Dubner thought he had a penicillin allergy. Like the vast majority, he didn’t. This misdiagnosis costs billions of dollars and causes serious health problems, so why hasn’t it been fixed? We find out in this update of a 2025 episode.   SOURCES: Kimberly Blumenthal, allergist-immunologist and researcher at the Mayo Clinic. Theresa MacPhail, associate professor of science and technology studies at Stevens Institute of Technology. Thomas Platts-Mills, professor of medicine at the University of Virginia. Elena Resnick, allergist and immunologist at Mount Sinai Hospital.   RESOURCES: Allergic: Our Irritated Bodies in a Changing World, by Theresa MacPhail (2023). "Evaluation and Management of Penicillin Allergy: A Review," by Erica S. Shenoy, Eric Macy, and Theresa Rowe (JAMA, 2019). "The Allergy Epidemics: 1870–2010," by Thomas Platts-Mills (The Journal of Allergy and Clinical Immunology, 2016). "Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy," by George Du Toit, Graham Roberts, et al. (The New England Journal of Medicine, 2015).   EXTRAS: "The Freakonomics Radio Guide to Getting Better," series by Freakonomics Radio (2026). "Doctors Know They Prescribe Too Many Antibiotics. Why Don’t They Stop?" by Freakonomics, M.D. (2022). Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.