What is the appropriate dose of polyethylene glycol 3350 (Restoralax) for a 28‑lb (≈12.7 kg) child?

Restoralax Dosing for a 28-Pound Child

For a 28-pound (12.7 kg) child with functional constipation, start polyethylene glycol 3350 (Restoralax) at 0.8 to 1.0 g/kg/day, which equals approximately 10 to 13 grams daily, mixed in 4-8 ounces of liquid. 1, 2

Initial Dosing Strategy

• Begin with 10-12 grams (approximately 1 capful or 17 grams of powder) once daily, as this represents the evidence-based starting point for a child of this weight 1, 2
• The mean effective dose in clinical trials was 0.84 g/kg/day (range 0.27-1.42 g/kg/day), which translates to roughly 11 grams for this 12.7 kg child 1
• For infants and toddlers specifically, studies demonstrated efficacy at a mean dose of 1.1 g/kg/day short-term and 0.8 g/kg/day long-term 2

Dose Titration Protocol

• Adjust the dose every 2-3 days based on stool output, aiming for 1-2 soft, painless bowel movements per day 1, 2
• If constipation persists after 3 days at the initial dose, increase by 2-4 grams daily increments 1
• If diarrhea develops (the only significant adverse effect reported), reduce the dose immediately 2, 3
• The therapeutic range is wide: some children require as little as 3-4 grams daily (0.27 g/kg) while others need up to 18 grams daily (1.42 g/kg) 1

Administration Instructions

• Mix the powder in any beverage (juice, water, milk) as it is tasteless and dissolves completely 3
• Administer once daily, preferably at the same time each day for consistency 1
• The medication can be given with or without food 2

Safety Profile for This Age Group

• Polyethylene glycol 3350 without electrolytes is safe and effective for children under 2 years of age, though this 28-pound child likely falls into the 1-3 year range 2
• In a study of 75 children under 24 months, constipation resolved in 85% with short-term therapy and 91% with long-term therapy 2
• No children discontinued therapy due to adverse effects in pediatric trials 1, 2
• The only reported side effect is diarrhea (occurring in approximately 9-12% of patients), which resolves with dose reduction 2, 3

Expected Timeline and Outcomes

• Expect improvement within 3-7 days of starting therapy, with stool frequency increasing from baseline (often 2-3 stools per week) to 10-15 stools per week 1
• Stool consistency should improve from hard (Bristol scale 1-2) to soft-formed (Bristol scale 3-4) 1
• Long-term therapy is safe; children in studies remained on PEG for an average of 11 months without significant adverse effects 2

Critical Monitoring Points

• Track daily stool frequency and consistency using a diary or log 1
• Monitor for signs of over-treatment (loose stools, diarrhea, abdominal cramping) 2
• If constipation persists despite adequate dosing (>1.0 g/kg/day), reassess for underlying organic causes or consider referral to pediatric gastroenterology 3
• Children who remain constipated despite therapy may have incomplete bowel emptying and require additional evaluation 3

Common Pitfall to Avoid

Do not underdose. Many providers start with adult-sized doses (17 grams) regardless of weight, which may be excessive for smaller children, or conversely, use doses that are too conservative (<0.5 g/kg/day), leading to treatment failure 1, 2. The weight-based approach (0.8-1.0 g/kg/day) optimizes efficacy while minimizing side effects.