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Introduction: Trimethoprim-sulfamethoxazole allergy can complicate treatment for various infections. While trimethoprim-sulfamethoxazole hypersensitivity, desensitization/oral challenges are frequently reported in adults, data is limited on the outcomes/safety of oral challenges to trimethoprim-sulfamethoxazole in Pediatrics. The goal of this study was to characterize the outcomes and safety of trimethoprim-sulfamethoxazole oral challenges in Pediatrics.

Methods: An IRB-exempt retrospective chart review was performed of pediatric patients who underwent oral challenge to trimethoprim-sulfamethoxazole in Allergy Clinic over the last 12 years. We assessed characteristics including age, sex, reaction (IgE-mediated/non-IgE-mediated/indeterminate), skin testing, challenge outcome and complications to draw a conclusion regarding the overall safety of the procedure in the pediatric population.

Results: Eleven patients were identified who underwent trimethoprim-sulfamethoxazole skin testing and/or oral challenge. Two reactions were consistent with an IgE-mediated process while the remainder were non-IgE-mediated/indeterminate. Two underwent skin testing to trimethoprim-sulfamethoxazole; both negative. Ten patients underwent successful oral challenge to trimethoprim-sulfamethoxazole; the eleventh patient was lost to follow-up after skin testing.

Conclusion: Trimethoprim-sulfamethoxazole hypersensitivity is infrequently evaluated in the Pediatrics. However, trimethoprim-sulfamethoxazole is an effective antibiotic and reported allergy limits treatment for infections. Evaluation of the initial reaction is necessary, as many patients have non-IgE-mediated/indeterminate reactions. Severe cutaneous adverse reactions should be evaluated for when considering candidates for oral challenge to trimethoprim-sulfamethoxazole as oral challenge is contraindicated in these patients. Overall, this study demonstrated that oral challenge to trimethoprim-sulfamethoxazole is a safe procedure to perform in select pediatric patients and can be done safely in the outpatient setting. One limitation was small sample size.

Educational Objective: Upon completion of this session, participants should be able to discuss the overall safety of oral challenges to Bactrim in the pediatric population.


Allergy and Immunology


Presented at the American College of Allergy, Asthma and Immunology Annual Meeting. New Orleans, LA. November 4-8, 2021.

Evaluation of the Outcomes of Trimethoprim-Sulfamethoxazole Oral Challenges in the Pediatric Population