What is the recommended dose of lactulose (a laxative) for a pediatric patient?

Lactulose Dosing in Pediatric Patients

For constipation in children, start with lactulose 2.5-10 mL daily in divided doses for infants, and 40-90 mL daily for older children and adolescents, titrating to achieve 2-3 soft stools daily. 1

Age-Specific Dosing Guidelines

Infants (Under 6 Months)

• Initial dose: 2.5-10 mL daily in divided doses 1
• Lactulose/lactitol-based medications are authorized and effective before 6 months of age 2
• If diarrhea develops, reduce the dose immediately; if diarrhea persists, discontinue lactulose 1

Older Children and Adolescents

• Initial dose: 40-90 mL daily in divided doses 1
• Adjust dose to produce 2-3 soft stools daily 1
• For children over 6 months, polyethylene glycol is also an authorized alternative 2

Disimpaction Therapy (When Fecal Impaction Present)

For fecal disimpaction, use higher-dose lactulose at 4-6 mL/kg/day (maximum 120 mL/day) until resolution or up to 6 days. 3

• This aggressive dosing approach has been shown to be safe and effective in achieving successful disimpaction by day 7 3
• Continue high-dose therapy until impaction resolves, then transition to maintenance dosing 3, 2

Critical Dosing Principles

Therapeutic Goal

• The target is 2-3 soft stools daily, not a specific volume of medication 1
• Adjust dose every 1-2 days based on stool frequency and consistency 1

Common Pitfall: Underdosing

• The rule for treatment is a sufficient dose for a long time 2
• Treatment is often delayed or inadequate, leading to psychosocial and digestive consequences 2
• Children require relatively higher doses per kilogram than adults due to differences in drug elimination that do not scale linearly with weight 4, 5

Monitoring and Adjustment

• If initial dose causes diarrhea (>3 loose stools daily), reduce immediately 1
• If no response after appropriate dosing, investigate for underlying issues rather than escalating indefinitely 6
• Monitor for perianal skin irritation with chronic use 6

Duration of Therapy

Maintenance therapy should continue for an extended period to prevent relapse, typically several months to years depending on severity. 2

• Education regarding daily bowel habits should accompany pharmacotherapy to restore colonic motility 2
• Discontinuation should be gradual after establishing regular bowel patterns 2

Safety Considerations

• Lactulose is safe and well-tolerated in pediatric patients when dosed appropriately 3
• Overuse can lead to dehydration, electrolyte imbalances, and severe perianal irritation 7, 6
• Very little formal data exists on lactulose use in young children, but clinical experience supports its safety 1