What is the pediatric dosage for polyethylene glycol (PEG) for constipation relief?

Pediatric Dosage for Polyethylene Glycol (PEG)

For functional constipation in children, start PEG 3350 at 0.8 g/kg/day (or approximately 1 g/kg/day initially) and titrate to achieve 1-2 soft, painless stools daily. 1, 2, 3

Age-Specific Dosing

Infants and Toddlers (<18 months)

• Initial dose: 0.88 g/kg/day 1
• Effective maintenance dose: 0.78 g/kg/day (range 0.26-1.26 g/kg/day) 1
• Efficacy: 97.6% response rate in this age group 1
• Safety profile: Similar to older children, with only transient diarrhea requiring dose adjustment 1

Children 18 months to 2 years

• Initial dose: 1 g/kg/day 2
• Short-term effective dose: 1.1 g/kg/day (mean at 2 months) 2
• Long-term effective dose: 0.8 g/kg/day (mean at 11 months) 2
• Efficacy: 85% relief at short-term follow-up, 91% at long-term follow-up 2

Children >2 years

• Initial dose: 1 g/kg/day 3
• Mean effective dose: 0.84 g/kg/day (range 0.27-1.42 g/kg/day) 3
• Alternative dosing: 1.0-1.5 g/kg/day has been studied with 95.3% success rate 4

Titration Strategy

Adjust the dose every 3 days based on stool frequency and consistency to achieve the target of 1-2 soft stools per day. 2, 3

• If diarrhea occurs, reduce the dose immediately—this is the most common side effect and resolves with dose adjustment 1, 2
• No maximum dose is clearly defined, but titrate based on symptom response and tolerability 5
• PEG maintains efficacy over 6 months without loss of effect 5

Special Considerations for Colonoscopy Preparation

For colonoscopy preparation specifically, use 1.5 g/kg/day for 4 days prior to the procedure, with a clear liquid diet on day 4. 6

• This higher dose is appropriate for bowel cleansing rather than chronic constipation management 6
• Maintain adequate hydration, especially in young children 6
• PEG causes significantly fewer mucosal lesions (2.3%) compared to sodium phosphate (24.5%) 6

Safety Profile

PEG 3350 is well-tolerated across all pediatric age groups with minimal adverse effects. 1, 2, 3

• Common side effects: bloating, abdominal discomfort, flatulence, and transient diarrhea that resolves with dose adjustment 5, 1
• No children discontinued therapy due to adverse effects in major studies 2
• PEG is tasteless and has superior palatability compared to alternatives like milk of magnesia 7, 3
• Ensure adequate hydration as this is an osmotic laxative 5

Clinical Outcomes

PEG significantly increases stool frequency from baseline 2.3 stools/week to 16.9 stools/week and improves stool consistency. 3

• In children with encopresis, soiling events decrease from 10 episodes/week to 1.3 episodes/week 3
• Response is durable over long-term treatment (mean 11 months) 2
• PEG has at least equivalent efficacy to liquid paraffin but with fewer adverse events 4