Which gastrointestinal side effects are most frequently reported with oral erythromycin ethylsuccinate?

With oral erythromycin ethylsuccinate, gastrointestinal side effects are the most frequent and dose-related; reported effects include upper abdominal discomfort, nausea, vomiting, diarrhoea, pancreatitis, anorexia and infantile hypertrophic pyloric stenosis, while pseudomembranous colitis is rarely reported.