What is the recommended dose of MiraLAX (polyethylene glycol) for pediatric patients?

MiraLAX Pediatric Dosing

For children 17 years and older, the FDA-approved dose is 17 grams (one capful or packet) dissolved in 4-8 ounces of any beverage once daily for up to 7 days; for children 16 years and under, the FDA label states to "ask a doctor" as there is no FDA-approved pediatric dose, though clinical evidence supports weight-based dosing of 0.5-1.5 g/kg/day. 1

FDA-Approved Dosing

• Adults and children ≥17 years: 17 grams (one capful or packet) dissolved in 4-8 ounces of beverage once daily, maximum 7 days 1
• Children ≤16 years: No FDA-approved dose; package labeling directs prescribers to individualize dosing 1

Evidence-Based Pediatric Dosing (Off-Label)

Maintenance Therapy for Functional Constipation

• Standard maintenance dose: 0.5-1.5 g/kg/day, typically divided into 1-2 doses 2, 3, 4
• Average effective dose in clinical studies: Approximately 0.63 g/kg/day 2
• Practical dosing: Most children respond to 0.5-1.0 g/kg/day as a starting dose, with titration based on response 4, 5

Colonoscopy Preparation

• Two-day bowel preparation: 1.5 g/kg divided twice daily for 2 days (total 3 g/kg over 2 days) 3
• This regimen demonstrated 88% excellent/good preparation quality in pediatric patients ages 6-21 years 3

Fecal Impaction (Disimpaction)

• Higher doses may be required: Up to 1.5 g/kg/day or higher for initial disimpaction 3, 5
• PEG is as effective as enemas for fecal impaction and avoids hospitalization 5

Administration Guidelines

• Dissolve powder completely in any beverage (cold, hot, or room temperature) before drinking 1
• Do not combine with starch-based thickeners used for dysphagia 1
• Do not drink if clumps remain after mixing 1
• Can be mixed with any liquid to improve palatability, which enhances compliance compared to large-volume PEG-electrolyte solutions 3, 4

Safety and Tolerability

• Most common adverse effect: Diarrhea, reported in approximately 20-26% of patients 2
• No serious adverse events reported in clinical trials 3
• Well-tolerated with high compliance rates in pediatric populations 2, 3, 4
• Non-addictive and tasteless, making it ideal for long-term use 2, 4

Clinical Efficacy

• Superior to placebo for functional constipation in both adults and children 5
• More effective than lactulose as an osmotic laxative 5
• First-line treatment for functional constipation in short and long-term management 5
• In children with dysfunctional elimination, PEG therapy significantly increased bowel movement frequency (p=0.0001), increased voided volume (146 vs 210 mL, p<0.0001), and decreased post-void residual urine (92 vs 48 mL, p<0.0001) 2

Important Clinical Considerations

• Duration of therapy: FDA labeling limits over-the-counter use to 7 days, but clinical practice often requires longer treatment courses under physician supervision 1, 4, 5
• Dose titration is essential: Approximately 50% of patients may require dose adjustment to achieve adequate response 2
• Persistent constipation despite therapy is associated with decreased resolution of associated symptoms (such as voiding dysfunction) and warrants dose escalation or alternative approaches 2
• Combination with behavioral interventions: PEG should be used as an adjunct to patient/parental education and behavioral training for optimal outcomes 4

Common Pitfall

Underdosing is a frequent error—if constipation persists on initial dosing (typically 0.5-0.7 g/kg/day), escalate the dose rather than switching agents, as many children require higher doses (up to 1.5 g/kg/day) for adequate response 2, 3