Recommended PEG Dose for a 3-Year-Old with Moderate Constipation
For a 3-year-old child with moderate functional constipation, start with polyethylene glycol (PEG) 3350 at 0.4 g/kg/day, which can be titrated up to 0.8-1 g/kg/day based on response, with a goal of producing 2-3 soft, painless stools daily. 1, 2
Initial Dosing Strategy
The North American Society for Pediatric Gastroenterology, Hepatology and Nutrition recommends PEG 3350 as the laxative of first choice for children 6 months and older, with initial dosing of 0.8-1 g/kg/day. 1
However, a multicenter placebo-controlled trial demonstrated that 0.4 g/kg/day is the optimal starting dose, as it provides excellent efficacy (74% treatment success) with fewer side effects than higher doses. 2
The 0.8 g/kg dose, while effective (73% success rate), was associated with more abdominal pain and fecal incontinence compared to the 0.4 g/kg dose. 2
Practical Dosing for a 3-Year-Old
For an average 3-year-old weighing approximately 14-15 kg, this translates to:
The powder can be mixed with any liquid to improve palatability and compliance. 3
Titration and Monitoring
Assess response after 1-2 weeks of treatment. 2
If constipation persists with the starting dose, increase incrementally toward 0.8-1 g/kg/day. 1
The goal is achieving 2-3 soft, painless bowel movements daily without fecal incontinence. 1
Studies show mean effective maintenance doses typically range from 0.61-0.78 g/kg/day in most children. 4, 3
Evidence Supporting PEG as First-Line
PEG is significantly more effective than placebo, increasing stool frequency by 2.61 stools per week. 5
PEG is superior to lactulose, producing 0.70 more stools per week and requiring fewer additional laxative therapies (18% vs 31%). 5
The American Academy of Pediatrics identifies PEG as the most effective intervention for functional constipation in children. 6
Safety Profile
PEG 3350 has an excellent safety profile with only minor adverse events reported. 7
Common side effects include transient diarrhea (which resolves with dose adjustment), flatulence, and mild abdominal discomfort. 4, 2
No serious adverse events have been reported in pediatric studies. 7, 5
In patients predisposed to water and electrolyte imbalances, monitoring of serum electrolytes should be considered, though this is rarely necessary in otherwise healthy children. 7
Duration of Treatment
Maintenance therapy must continue for many months (often 6+ months) before the child regains normal bowel motility and rectal perception. 1, 4
A critical pitfall is premature discontinuation—parents often cease treatment too soon, leading to relapse rates of 40-50% within 5 years. 1