Lactulose Dosing for a 3-Year-Old Child Weighing 13kg
For a 3-year-old child weighing 13kg with constipation, start with 2.5-5 mL of lactulose syrup once or twice daily, with the goal of producing 2-3 soft stools per day. 1
Initial Dosing Strategy
The FDA-approved pediatric dosing for lactulose in infants starts at 2.5-10 mL daily in divided doses, with older children and adolescents requiring 40-90 mL total daily dose. 1
For a 3-year-old weighing 13kg, this child falls into the "older infant/young child" category, so an appropriate starting dose would be 5 mL once or twice daily (total 5-10 mL/day). 1
The lactulose syrup concentration is typically 10 g/15 mL (approximately 667 mg/mL), so 5 mL provides approximately 3.3 grams of lactulose. 1
Dose Titration and Monitoring
Adjust the dose every 1-2 days based on stool frequency and consistency, with the therapeutic goal being 2-3 soft, non-forced bowel movements daily. 2, 1
If the initial dose causes diarrhea, reduce the dose immediately; if diarrhea persists, discontinue lactulose. 1
Allow adequate time for assessment before increasing the dose—improvement may occur within 24 hours but may not begin before 48 hours or even later. 3, 1
Gradual upward titration is recommended if constipation persists, based on symptom response and side effects. 3
Practical Considerations
Common side effects include bloating and flatulence, which are dose-dependent and occur in approximately 20% of patients. 2, 3
In preverbal or young children, side effects such as excessive gas, abdominal discomfort, and diarrhea may be more difficult to assess, requiring careful parental observation. 3
Ensure adequate hydration while using lactulose, as it works by drawing water into the intestine to soften stool. 3
Lactulose is considered safe, effective, and well-tolerated in constipated children with a favorable safety profile. 3
Maximum Dosing Limits
For this age group, the total daily dose can be increased up to approximately 20-30 mL/day if needed, but should not exceed what produces adequate bowel movements. 1
Avoid excessive dosing beyond what produces adequate bowel movements, as overuse can lead to dehydration, electrolyte disturbances, and severe perianal skin irritation. 4
Clinical Pitfalls to Avoid
If no response occurs after 48-72 hours of appropriate dosing, rule out fecal impaction before escalating the lactulose dose. 4
Do not simply escalate doses without investigating for impaction, obstruction, or other precipitating factors, as this can lead to complications without improving outcomes. 4