Otitis media occurs commonly in children, and is usually treated with an antibiotic. In this case report, amoxicillin was prescribed for a 6-year-old boy suffering from acute otitis media. As he had previously experienced a rash after the administration of a penicillin, the medication order was switched from amoxicillin to trimethoprim/sulfamethoxazole (TMP/SMX). In an effort to determine whether or not this intervention was appropriate, references were found using Medline, International Pharmaceutical Abstracts and the Cochrane Library. Issues to be addressed included the need for antibiotics in acute otitis media, the comparative efficacy and tolerability of antimicrobial agents and the reliability of reported penicillin allergies. Amoxicillin and TMP/SMX were found to be first-line agents in the treatment of acute otitis media owing to their efficacy, safety and cost, with neither drug being significantly better than the other. The need to treat otitis media with antibiotics remains controversial. Reported penicillin allergies were found to be an unreliable indicator of a potentially serious reaction. In conclusion, it was found that treatment with TMP/SMX was an appropriate intervention.