What medications are recommended for treating constipation in pediatric patients?

Medications for Pediatric Constipation

Polyethylene glycol (PEG) 3350 is the first-line medication for treating constipation in pediatric patients of all ages, including infants, with a starting dose of 0.4-0.8 g/kg/day titrated to achieve 2-3 soft stools daily. 1, 2

First-Line Treatment: PEG 3350

PEG 3350 should be used as the gold standard initial therapy due to superior efficacy, safety profile, and cost-effectiveness compared to other laxatives. 1

Dosing by Age:

• Infants (<18 months): Start with 0.78-0.88 g/kg/day (mean effective dose 0.78 g/kg/day), which has been proven safe and effective even in this young population 3

• Children 1-5 years: Start with 0.4 g/kg/day, which provides optimal balance between efficacy and side effects 2

• Older children and adolescents: Start with 17 g daily (approximately 0.4-0.8 g/kg/day depending on weight), titrating based on response 1, 4

Key Clinical Points:

• Titrate the dose every 2-3 days based on stool frequency and consistency to achieve 2-3 soft stools daily 2, 4

• PEG 3350 demonstrates 97.6% efficacy in relieving constipation across all pediatric age groups 3

• PEG 3350 is significantly more effective than lactulose (56% vs 29% success rate) with fewer side effects including less abdominal pain, straining, and pain at defecation 5

• The medication is tasteless and can be mixed with any liquid, improving compliance 6

Second-Line Treatment: Lactulose

If PEG 3350 is unavailable or not tolerated, lactulose is an acceptable alternative osmotic laxative. 7, 1

Dosing by Age:

• Infants: Start with 2.5-10 mL daily in divided doses 8

• Older children and adolescents: Total daily dose of 40-90 mL 8

• General adult dosing (for reference): 30-45 mL three to four times daily 8

Important Caveats:

• Titrate gradually upward if constipation persists, based on symptom response 7

• Allow 24-48 hours or longer before assessing response and increasing dose 7, 8

• Bloating and flatulence are dose-dependent and represent the most common limiting factors 7

• In preverbal infants, side effects like excessive gas, abdominal discomfort, and diarrhea may be difficult to assess, requiring careful parental observation 7

• If diarrhea occurs, reduce the dose immediately; if it persists, discontinue lactulose 8

Third-Line Treatment: Stimulant Laxatives

Use stimulant laxatives only for short-term rescue therapy when osmotic laxatives provide inadequate response. 1

• Bisacodyl: 5-10 mg daily (maximum 10 mg daily) 1

• Senna: 8.6-17.2 mg daily (maximum 4 tablets twice daily), though long-term safety in pediatrics is unknown 1

Treatment Algorithm

1. Start with PEG 3350 at age-appropriate dose (0.4-0.8 g/kg/day) 1, 2

2. If inadequate response after 2-3 days, titrate PEG dose upward based on clinical response 1

3. If PEG alone fails, add or switch to stimulant laxatives (bisacodyl or senna) for short-term use 1

4. Ensure adequate hydration and dietary fiber (14 g per 1,000 kcal daily) as adjunctive measures 1

Common Pitfalls to Avoid

• Do not use doses of 0.8 g/kg or higher as starting dose in children, as this increases abdominal pain and fecal incontinence 2

• Do not assume lactulose and PEG are equivalent—PEG has superior efficacy and tolerability 5

• Do not increase lactulose dose too quickly—improvement may not begin before 48 hours or even later 7, 8

• Do not use stimulant laxatives as first-line therapy or for long-term maintenance 1

• In infants, monitor closely for side effects as they cannot verbalize discomfort 7