Background Osmotic and stimulant laxatives are the mainstay of treatment for children suffering with functional constipation. We systemically evaluated studies which had investigated osmotic and stimulant laxatives for functional constipation in children.

Methods Randomised controlled trials (RCTs), published between 1966 and October 2010, which compared osmotic and stimulant laxatives with either placebo or other interventions were included. Data sources were MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Inflammatory Bowel Disease and Functional Bowel Disorders Specialised Register and reference lists of retrieved articles. Data extraction and assessment of methodological quality were performed independently by two reviewers.

Results 16 RCTs met the inclusion criteria. Meta-analysis of four studies with 338 participants comparing polyethylene glycol (PEG) with Lactulose showed significantly greater stools/week with PEG (Mean difference 0.98, 95% CI 0.49 to 1.46). Those on PEG were less likely to require additional laxative therapies (OR 0.49, 95% CI 0.27 to 0.89). No serious adverse events were reported with either agent. Incidence of gastrointestinal symptoms, such as abdominal pain, nausea and vomiting, did not differ between groups. Heterogeneity among studies was noted, probably attributable to differences in concomitant medications and follow-up times between studies. Meta-analysis of two studies with 173 participants comparing PEG with Milk of magnesia showed that the stools/week was significantly greater with PEG (Mean difference 0.69, 95% CI 0.48 to 0.89). One child was noted to be allergic to PEG, but there were no other serious adverse events reported. Two studies compared PEG with placebo, but there was insufficient data to allow meta-analysis. Both studies reported a significantly increased number of stools per week (stools/week) with PEG. Meta-analysis of two studies with 287 patients comparing Paraffin with Lactulose showed that the stools/week following treatment was significantly greater with Paraffin (Mean difference 4.94, 95% CI 4.28 to 5.61). Again, no serious adverse events were reported.

Conclusions The available evidence suggests that PEG is more effective than placebo and that both liquid paraffin and PEG are more effective than Lactulose for treating children with functional constipation.