Lactulose Pediatric Dosing
For infants, the recommended initial dose is 2.5-10 mL daily in divided doses, and for older children and adolescents, 40-90 mL daily, with the goal of producing 2-3 soft stools per day. 1
Dosing by Age Group
Infants (Under 1 Year)
- Initial dose: 2.5-10 mL daily in divided doses 1
- For infants under 6 months, lactulose/lactitol-based medications are authorized and effective 2
- For infants over 6 months, polyethylene glycol becomes an additional option 2
- If diarrhea occurs, reduce the dose immediately; if diarrhea persists, discontinue lactulose 1
Older Children and Adolescents
- Total daily dose: 40-90 mL daily 1
- Divide the total dose throughout the day to maintain consistent effect 1
- The subjective goal is to produce 2-3 soft stools daily, same as in adults 1
Disimpaction Therapy (When Fecal Impaction Present)
- Higher dose lactulose: 4-6 mL/kg/day (maximum 120 mL/day) until resolution or up to 6 days 3
- This higher dosing regimen has been shown to achieve successful disimpaction by day 7 in all treated patients 3
- Alternative approach: repeated phosphate enemas can be used for disimpaction before starting maintenance therapy 2
Administration Principles
- Dose adjustment is critical: If the initial dose causes diarrhea, reduce immediately 1
- The treatment goal remains consistent across all ages: 2-3 soft bowel movements per day 1
- Treatment duration must be sufficient and prolonged to prevent relapse 2
- Very little information exists on lactulose use in young children and adolescents compared to adults, so careful monitoring is essential 1
Important Clinical Pitfalls
- Insufficient dosing duration: Treatment must continue long enough to restore colonic motility and prevent relapses 2
- Premature discontinuation: Stopping too early leads to recurrence of constipation 2
- Overdosing complications: Excessive use can cause dehydration, hypernatremia, and severe perianal skin irritation 4, 5
- Common side effects: Bloating and flatulence are dose-dependent and may limit use 6
Evidence Quality
Lactulose demonstrates effectiveness and safety for both disimpaction and maintenance therapy in constipated children 3, and remains one of the most effective osmotic laxatives for both short and long-term treatment of pediatric functional constipation 7. The medication is cheap, widely available, and well-tolerated with no significant adverse events reported in controlled trials 3.