First-Line Osmotic Laxative for Toddler Constipation
Polyethylene glycol (PEG) 3350 is the first-line osmotic laxative for toddlers with constipation unresponsive to dietary measures, starting at approximately 0.8 g/kg/day (roughly 1 capful or 17g mixed in 8 oz of liquid once daily for most toddlers). 1, 2, 3
Why PEG Over Other Osmotic Laxatives
PEG demonstrates superior efficacy compared to all other laxatives in pediatric constipation. The evidence strongly favors PEG:
- PEG achieves significantly more treatment success than other laxatives, with a pooled relative risk of 1.47 (95% CI 1.23-1.76) 4
- In toddlers specifically (ages 12-17 months), PEG relieves constipation in 97.6% of patients at a mean maintenance dose of 0.78 g/kg/day 3
- The 2023 American Gastroenterological Association-American College of Gastroenterology guidelines provide a strong recommendation for PEG use in chronic constipation, with moderate certainty of evidence 1
Lactulose, while an alternative osmotic laxative, is less effective. Studies show lactulose is less than or equally effective compared to other laxatives in increasing defecation frequency 4. When directly compared to PEG in head-to-head trials, lactulose produces comparable defecation frequency but harder stool consistency 5.
Specific Dosing for Toddlers
Start with 0.8-1.0 g/kg/day of PEG 3350, which translates to approximately 1 capful (17g) mixed in 8 oz of water or juice once daily for an average toddler (12-15 kg). 2, 3
- For younger toddlers (12-17 months), the effective maintenance dose ranges from 0.26-1.26 g/kg/day, with a mean of 0.78 g/kg/day 3
- The dose can be adjusted based on response, with the goal of producing 2-3 soft, painless bowel movements daily 1, 2
- Response is typically seen within 2-4 days, though it may take up to 48 hours or longer 6
Safety Profile
PEG is remarkably safe in toddlers with minimal side effects. 3
- Common side effects include abdominal distension, loose stools, flatulence, and nausea 1
- In infants and toddlers under 18 months, only transient diarrhea (resolved with dose adjustment) and increased gas were reported 3
- PEG has demonstrated durable response over 6 months of continuous use 1
Alternative: Lactulose (If PEG Unavailable)
If PEG is not available or not tolerated, lactulose is the second-line osmotic laxative. 1, 6
- Dosing for toddlers: Start with 2.5-10 mL daily in divided doses for younger toddlers, or up to 40 mL daily for older toddlers 6
- Lactulose works by drawing fluid into the bowel and producing osmotic diarrhea of low pH 1
- The main disadvantage is that it may cause more flatulence and abdominal discomfort compared to PEG 5
Important Clinical Caveats
Before initiating osmotic laxatives, ensure adequate fluid intake is maintained. 2
- Fiber supplementation should only be increased if the child has adequate fluid intake and physical activity 2
- The sorbitol in prune, pear, and apple juices that you've already tried works through the same osmotic mechanism as lactulose 1
If no improvement occurs after 3 weeks of PEG therapy, consider adding a stimulant laxative (bisacodyl 10-15 mg daily) rather than switching osmotic agents. 2
Rule out red flags before starting treatment: delayed meconium passage, failure to thrive, abdominal distension, abnormal anal position, or absent anal/cremasteric reflexes suggest organic causes requiring further evaluation 2