Int Arch Allergy Immunol

Penicillin treatment during mono linked to lasting drug allergies in teens and adults

August 22, 2025

Study details: This retrospective analysis included adolescent and adult patients who developed maculopapular rashes after penicillin treatment for infectious mononucleosis (IM) who underwent subsequent formal allergy testing. The cohort included 15 patients identified from hospital records, with documentation of rash characteristics, duration, and outcomes of skin testing.

Results: Nearly half of the cohort demonstrated evidence of persistent penicillin allergy on skin testing, with positive results more frequent among those with prolonged or recurrent reactions. Several patients experienced repeat drug hypersensitivity reactions upon re-exposure prior to allergy evaluation.

Clinical impact: These findings challenge current prescribing practices and suggest clinicians should avoid aminopenicillins in confirmed or suspected IM cases. Patients who received penicillins during IM should be considered potentially allergic long-term and may require formal allergy testing before future beta-lactam exposure.

Source:

Cao LM, et al. (2025, August 13). Int Arch Allergy Immunol. Penicillin treatment in infectious mononucleosis may lead to persistent drug allergy in adolescents and adults even after years. https://pubmed.ncbi.nlm.nih.gov/40815123/