Antibiotic-associated gastrointestinal symptoms in general pediatric outpatients.

As part of an intensive program of surveillance for adverse drug reactions in general pediatric outpatients, 2,714 courses of oral antibiotic therapy were monitored for the occurrence of gastrointestinal (GI) adverse drug reactions. Using a recently developed algorithm to establish a causal link between drugs and adverse symptoms, the risks of diarrheal or upper GI tract adverse drug reactions were found to vary considerably with different antimicrobial agents and, for several agents, according to the administered dosage. For diarrhea, the risk was lowest with sulfasoxazole and trimethoprim/sulfamethoxazole and was highest with cloxacillin. A significant dose-response effect was found with both amoxicillin and trimethoprim/sulfamethoxazole. For upper GI tract adverse drug reactions, the risk was again lowest with sulfasoxazole and trimethoprim/sulfamethoxazole and was highest with erythromycin. Knowledge of the risks of gastrointestinal adverse drug reactions with different agents and different doses should be clinically helpful in assessing risks and benefits when oral antibiotics are prescribed for children.