Lactulose Dosing for 11-Month-Old Infant with Constipation
For an 11-month-old infant weighing 9 kg with constipation, start with lactulose 2.5-10 mL daily in divided doses, titrating based on response to achieve 2-3 soft stools daily. 1
Recommended Dosing Approach
Initial Dose
- Start with 2.5-10 mL daily in divided doses for infants, as specified in the FDA labeling 1
- For a 9 kg infant, a practical starting dose would be 5 mL once or twice daily (total 5-10 mL/day) 1
- The goal is to produce 2-3 soft stools daily 1
Dose Titration
- If diarrhea occurs, reduce the dose immediately 1
- If diarrhea persists despite dose reduction, discontinue lactulose 1
- Titrate upward gradually if constipation persists, based on symptom response and side effects 2
- Research supports dosing ranges of 4-6 mL/kg/day for disimpaction (maximum 120 mL/day), though this is higher than typical maintenance dosing 3
Clinical Considerations for Infants
Safety Profile
- Lactulose is the only osmotic agent specifically studied in pregnancy, suggesting a favorable safety profile 2, 4
- The FDA label provides specific pediatric dosing guidance for infants, indicating established use in this age group 1
- Research demonstrates lactulose is safe, effective, and well-tolerated in constipated children 3
Common Side Effects
- Bloating and flatulence are dose-dependent and represent the most common limiting factors 2, 4
- Monitor for excessive gas, abdominal discomfort, and diarrhea 4
- These side effects may be more difficult to assess in preverbal infants, requiring careful parental observation
Practical Administration
- Ensure adequate hydration while using lactulose 4
- Lactulose can be mixed with formula, juice, or water to improve palatability
- Divided dosing (twice daily) may reduce side effects compared to once-daily administration 1
Important Caveats
Response Timeline
- Improvement may occur within 24 hours but may not begin before 48 hours or even later 1
- Allow adequate time for assessment before increasing the dose
Alternative Considerations
- While polyethylene glycol (PEG) shows higher success rates in older children (56% vs 29% for lactulose), the FDA label provides specific infant dosing only for lactulose 1, 5
- Research in children aged 6 months-15 years found PEG more effective with fewer side effects, but lactulose remains a reasonable first-line option given its established safety profile in infants 5
When to Reassess
- If no response after several days of appropriate dosing, consider evaluation for fecal impaction
- If side effects are intolerable despite dose reduction, alternative therapies should be considered