At the 2014 meeting of the American College of Allergy, Asthma and Immunology, the Mayo Clinic’s Dr. Thanai Pongdee reported the results of his ongoing penicillin allergy study. Dr. Pongdee’s team tested 384 patients who all reported penicillin allergy. A shocking 94 percent of the tests came back negative. In a second Mayo Clinic study of 38 self-declared penicillin allergic people, no one tested positively for the allergy.
A Canadian study also found that more than 98 percent of patients with a history of penicillin allergy tested negative for the allergy, but the patients’ new allergy-free status was often not properly recorded on their medical charts.
These findings, along with Dr. Pongdee’s recent study, bolster earlier suggestions that the allergy is not as widespread as once thought and it could be worth seeing an allergist to see if you too have outgrown the allergy. Penicillin antibiotics are more effective and often cheaper than the alternative drugs.
While it’s still unknown why so many people react to penicillin at some point in their lives, one strong association has emerged between infectious mononucleosis and penicillin allergy.
A decade-long Allergy Asthma and Clinical Immunology study followed 10 patients who were being treated for infectious mononucleosis, also known as “mono”. All patients broke out into hives after being treated with penicillin-based antibiotics. Following the allergic reaction, testing revealed an association between developing penicillin sensitivity and the disease.
In cases where patients with infectious mononucleosis react to penicillin additional testing appears to be necessary, as these patients often won’t react to a skin prick test, but they will react if an intradermal test (deeper under the skin) is conducted.