A Cochrane review included 10 studies with a total of 868 subjects (322 adults and 546 children). Polyethylene glycol was better than lactulose in outcomes of stool frequency per week (MD 0.65, 95% CI 0.15 to 1.15, statistical heterogeneity I2=77%; 5 studies, n=407), form of stool (MD 0.89, 95% CI 0.43 to 1.35, statistical heterogeneity I2=88%; 2 studies, n=301), relief of abdominal pain (OR 2.09, 95% CI 1.26 to 3.44, I2=44%; 3 studies, n=300) and the need for additional products (OR 4.00, 95% CI 2.01 to 7.95; 3 studies, n=225). On subgroup analysis, this was seen in both adults and children, except for relief of abdominal pain.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment).