PEG is Superior to Lactulose for Pediatric Constipation
For children with constipation, polyethylene glycol (PEG) should be used as the first-line laxative over lactulose, as it demonstrates superior efficacy in increasing stool frequency, improving stool consistency, and is better tolerated by children. 1, 2, 3
Evidence Supporting PEG as First-Line Treatment
Efficacy Outcomes
PEG increases stool frequency significantly more than lactulose. In a randomized, double-blind trial of 88 children aged 12-36 months, PEG 4000 (8 g/day) increased stool frequency by 0.51 stools/day compared to only 0.15 stools/day with lactulose, with a statistically significant difference of 0.36 stools/day (95% CI: 0.16-0.56). 3
PEG improves stool consistency and ease of passage better than lactulose (p = 0.001), which directly impacts quality of life for children and caregivers. 3
PEG reduces total colonic transit time more effectively than lactulose (47.6 vs 55.3 hours, p = 0.038), demonstrating superior physiologic efficacy. 4
Meta-analysis confirms PEG superiority: A comprehensive meta-analysis of multiple studies demonstrated that PEG-based laxatives are more effective than lactulose for both chronic constipation and fecal disimpaction in children. 2
Safety and Tolerability
PEG has an excellent safety profile across all pediatric age groups, including infants as young as 0-5 months, with only minor adverse events reported (transient diarrhea in 14% that resolved with dose adjustment). 5, 1
Adverse event rates are similar between PEG and lactulose, with both being generally well tolerated, but PEG has better palatability and acceptance by children. 2, 3
PEG maintains efficacy over 6 months without loss of effect, making it suitable for long-term management. 6
Practical Dosing Recommendations
Initial and Maintenance Dosing
Start PEG 3350 at 0.8-1.0 g/kg/day for children, which can be given as a single daily dose mixed in liquid. 5
Adjust the dose every 3 days based on stool frequency and consistency to achieve the target of 1-2 soft stools per day. 6
The effective maintenance dose averages 0.78 g/kg/day (range 0.26-1.26 g/kg/day) in infants and young children. 5
Age-Specific Considerations
PEG is safe and effective even in infants younger than 18 months, with 97.6% experiencing relief of constipation at a mean dose of 0.78 g/kg/day. 5
Maintain adequate hydration, especially in young children, as PEG is an osmotic laxative that draws water into the colon. 7, 6
Important Clinical Caveats
Monitor electrolytes in predisposed patients: While PEG is generally safe, children with conditions predisposing to water and electrolyte imbalances should have serum electrolytes monitored. 1
Lactulose may cause more bloating and flatulence due to bacterial fermentation in the colon, which can reduce compliance in children. 2
PEG's efficacy is dose-dependent, so inadequate dosing is a common pitfall—don't hesitate to titrate upward based on response. 1