Considering the Label: Characterization of Antibiotic Allergy Labeling in Successful Pediatric Amoxicillin Dose Challenges

Background: Penicillin allergy is reported by approximately 10% of the population, but less than 5% of these presumed allergies are associated with reactions. Reported antibiotic allergies are linked to increased health care utilization and cost, and often result in prescription of broader-spectrum antibiotics with more side-effects and antibiotic resistance. In evaluation of medication allergy, IgE-mediated reactions can be identified by specific features of the history including: necessary pre-sensitization by prior exposure to the antibiotic, onset of symptoms within the first few doses of the course, and presence of a histamine-related rash which resolves soon after cessation of therapy. While antibiotic allergy de-labeling has been shown to improve patient outcomes and costs, there is little research regarding the pre-labeling setting where an allergy is documented. This retrospective cohort study aimed to characterize the process of allergy labeling for pediatric patients who eventually tolerated an amoxicillin challenge, in order to note any findings which could change the labeling outcomes.

Methods: 57 pediatric patients with amoxicillin allergy label underwent a successful single dose amoxicillin challenge from 1/1/2018 through 10/31/2020. Patient charts were retrospectively analyzed using data abstraction forms to assess symptoms and physician documentation in the original encounters in which 1) the amoxicillin was prescribed, 2) amoxicillin-associated symptoms were evaluated, and 3) the allergy evaluation occurred. Patients were excluded if these evaluations were not recorded within the EHR.

Results: Thirty-four patients met study criteria. Twenty-seven (79%) patients were originally prescribed amoxicillin for otitis media and 20 (59%) had fever at the time of diagnosis. When evaluated for new symptoms during the treatment course, 26 (77%) were evaluated in-person. Of those who were evaluated, only 1 patient was found to have urticaria (three days after completion of the antibiotic course), though almost all patients had reported a rash. Seventeen (50%) of these patients had an allergy label recorded during their 1st lifetime prescription of amoxicillin. Thirty-three (97%) patients reported symptoms initiated after the first 24 hours of amoxicillin exposure.

Of this cohort of successful challenges, there were no patients identified with both pre-sensitization to the antibiotic as well as with symptoms noted within the first 24 hours of amoxicillin exposure. Notably, in the time between allergy label and challenge, 87 prescriptions for cephalosporins and azithromycin were given, which were likely impacted by allergy labeling.

Conclusion: In this review of circumstances surrounding the labeling of amoxicillin allergy in pediatric patients, the combination of lack of pre-sensitization and symptom onset >24 hours from initiation of antibiotic course predicted the ability to successfully tolerate amoxicillin. Further confirmation of this clearance criteria in expanded patient populations may help to promote antibiotic stewardship through an allergy pre-labeling intervention.