Lactulose Dosing for Infant Constipation
For infants with constipation, the recommended initial daily oral dose of lactulose is 2.5 mL to 10 mL in divided doses, which should be adjusted based on response. 1
Dosing Guidelines
- Initial dosing: 2.5 mL to 10 mL per day divided into multiple doses 1
- Dose adjustment: If the initial dose causes diarrhea, reduce the dose immediately
- Discontinuation: If diarrhea persists despite dose reduction, discontinue lactulose 1
- Goal of therapy: Produce 2-3 soft stools daily 1
Mechanism of Action
Lactulose is a synthetic disaccharide that acts as an osmotic laxative. It is not digested in the small intestine and exerts its effect in the colon by promoting peristalsis through its osmotic properties 2.
Efficacy in Infants
While lactulose is FDA-approved and effective for constipation in infants, studies comparing it to other agents have shown mixed results:
- A 2005 study found that liquid paraffin was more effective than lactulose in treating constipation in children, with faster response and fewer side effects 3
- A 2019 study demonstrated that both lactulose and polyethylene glycol (PEG) were effective for fecal disimpaction in constipated children, though PEG showed a faster response 4
Important Considerations
- Monitoring: Watch for response within 24-48 hours, though improvement may take longer 2
- Common side effects: Bloating and flatulence are common dose-dependent side effects 2
- Advantage: Lactulose is one of the few laxatives specifically approved for use in young infants 5
Alternative Options
If lactulose is ineffective or poorly tolerated:
- For infants over 6 months of age, polyethylene glycol (PEG) may be considered as an alternative 5
- Ensure adequate fluid intake unless contraindicated 6
Cautions
- Dose should be carefully titrated to avoid causing diarrhea
- Long-term use should be monitored as there is limited data on prolonged use in infants
- If constipation persists despite appropriate dosing, further evaluation may be needed to rule out other causes
Remember that the goal of treatment is to produce 2-3 soft stools daily without causing diarrhea or other adverse effects.