Lactulose Dosing for a 1-Year-Old Child with Constipation
For a 1-year-old child with constipation, start with 2.5 to 10 mL of lactulose syrup daily in divided doses, with the goal of producing 2-3 soft stools daily. 1
FDA-Approved Pediatric Dosing
- The FDA label specifies that for infants, the recommended initial daily oral dose is 2.5 mL to 10 mL in divided doses 1
- The subjective goal in proper treatment is to produce 2-3 soft stools daily 1
- If the initial dose causes diarrhea, reduce the dose immediately 1
- If diarrhea persists despite dose reduction, lactulose should be discontinued 1
Practical Dosing Strategy
- Start at the lower end of the range (2.5-5 mL daily) to minimize gastrointestinal side effects such as bloating, flatulence, and abdominal cramping 2
- Divide the total daily dose into 2-3 administrations throughout the day 1
- Titrate upward gradually over several days if inadequate response, monitoring stool frequency and consistency 2
- The maximum dose for infants should not exceed 10 mL daily without careful reassessment 1
Critical Safety Considerations
Dehydration and Electrolyte Monitoring
- Excessive lactulose can cause dehydration, hypernatremia, and severe perianal skin irritation in infants, making careful dose management essential 3
- Monitor for signs of dehydration, especially if the infant develops loose stools or diarrhea 3
- Aspiration risk increases if excessive diarrhea occurs due to lactulose overdose 3
Dose Adjustment Protocol
- If diarrhea occurs, reduce the dose immediately 1
- If diarrhea persists despite dose reduction, discontinue lactulose to prevent dehydration and electrolyte disturbances 3
- Do not increase doses excessively if there is lack of effect; instead, search for other causes or consider alternative therapies 3
Evidence Supporting Lactulose Use in Young Children
- Lactulose is an effective osmotic laxative that affects colonic fecal content, inducing evacuation in people with constipation 4
- A pilot study in premature infants demonstrated that 1% lactulose supplementation (approximately 1 mL per 100 mL of feeds) appeared safe and did not cause diarrhea, while showing potential prebiotic benefits 5
- Osmotic laxatives like lactulose remain among the most effective and safe therapies for both short and long-term treatment of pediatric functional constipation 6
Common Pitfalls to Avoid
- Do not use the adult dosing range (15-30 mL) in infants, as this dramatically exceeds the recommended pediatric dose and increases risk of adverse effects 7, 1
- Bloating and flatulence are dose-dependent side effects that commonly limit tolerability 7
- The misconception that much larger doses are needed for lack of effect is dangerous; instead, reassess the diagnosis or consider alternative therapies 3
- Lactulose should only be used after failure or intolerance to first-line therapies in older children, though it remains a reasonable option for infants 7