Quantitative comparison of adverse reactions to cefaclor vs. amoxicillin in a surveillance study.

During an 18-month adverse events surveillance period, children with a history of recurrent suspected or proved bacterial infections were treated with either cefaclor (1017 patients, 2513 courses) or amoxicillin (1009 patients, 2358 courses) and followed prospectively to determine the relative incidence and character of adverse events. Patients were from 1 month to 16 years old. Otitis media, the principal diagnosis, occurred in 883 patients (2014 episodes) receiving cefaclor and in 856 (1888 episodes) receiving amoxicillin. Others were diagnosed as having pharyngitis (482 episodes), bronchitis (267 episodes), sinusitis (130 episodes), pneumonia (63 episodes) and urinary tract infection (27 episodes). Adverse events were elicited by telephone during therapy and by follow-up for 2 weeks after therapy and were reported in 5.7% of the cefaclor courses and 5.2% of courses of amoxicillin. Serum sickness-like reactions and erythema multiforme occurred in 5 and 6 children, respectively, given cefaclor (1.1%) and in no children given amoxicillin. Children in the cefaclor group had a greater incidence of urticaria. Other adverse experiences, including gastrointestinal events, were approximately equally distributed for the two groups.