What is the recommended dosage of lactulose (a laxative medication) for children with constipation?

Lactulose Dosage for Children with Constipation

For pediatric constipation, lactulose should be dosed at 2.5-10 mL daily in divided doses for infants and 40-90 mL daily for older children and adolescents, with dose adjustments based on response to achieve 2-3 soft stools daily. 1

Dosage Guidelines by Age

• Infants: Initial daily oral dose of 2.5-10 mL in divided doses 1
• Older children and adolescents: Total daily dose of 40-90 mL 1
• For disimpaction therapy: Higher doses of 4-6 mL/kg/day (maximum 120 mL/day) may be used for short-term fecal disimpaction 2

Dosing Considerations

• The primary goal of lactulose therapy is to produce 2-3 soft stools daily 1
• Dose should be reduced immediately if diarrhea occurs 1
• If diarrhea persists despite dose reduction, lactulose should be discontinued 1
• Improvement may occur within 24-48 hours, but sometimes takes longer 1

Mechanism and Efficacy

• Lactulose is an osmotic laxative that works by drawing water into the intestine to soften stool 3
• Studies show lactulose is effective for treating constipation in children, though it may work more slowly than polyethylene glycol (PEG) 2, 4
• Lactulose has been shown to be more effective than placebo in increasing stool frequency in constipated patients 3

Side Effects and Monitoring

• Common side effects include bloating and flatulence, which are dose-dependent and may limit use 3
• These side effects are more common with lactulose than with some other laxatives like lactitol 5
• Monitor for excessive gas, abdominal discomfort, and diarrhea 3

Clinical Considerations

• Lactulose is generally well-tolerated but may cause more gastrointestinal side effects compared to PEG 4
• Studies comparing lactulose with senna found lactulose resulted in more days with normal stools and fewer side effects 6
• Lactulose has been studied in pregnancy and is considered one of the safer osmotic laxatives during pregnancy 3

Practical Administration Tips

• Lactulose has a sweet taste that some children may find acceptable 1
• Can be mixed with fruit juice, milk, or water to improve palatability 1
• Ensure adequate hydration while using lactulose 3
• For chronic constipation, polyethylene glycol (PEG) may be preferred as first-line therapy due to better efficacy and fewer side effects 4

When to Consider Alternative Treatments

• If lactulose causes persistent diarrhea or intolerable bloating/flatulence 1
• If there is inadequate response after appropriate dose titration 3
• Consider PEG as an alternative, which has been shown to decrease colonic transit time more effectively than lactulose 4