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

MiraLAX Dosing for Children

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 younger, the FDA label states to "ask a doctor" as there is no FDA-approved pediatric dose, though clinical evidence supports weight-based dosing of approximately 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; label directs to consult a physician 1
• The powder must be fully dissolved before drinking, and should not be consumed if clumps remain 1
• Can be mixed with cold, hot, or room temperature beverages 1
• Should not be combined with starch-based thickeners 1

Evidence-Based Pediatric Dosing (Off-Label)

While not FDA-approved for children under 17, substantial clinical evidence supports weight-based dosing:

Weight-Based Dosing Strategy

• Average effective dose: 0.63 g/kg/day based on clinical studies in children with dysfunctional elimination 2
• Typical dosing range: 0.5-1.5 g/kg/day, with most children responding to doses in this range 2, 3
• Colonoscopy preparation: 1.5 g/kg divided twice daily for 2 days has proven effective and safe 3

Practical Application

• For a child weighing 20 kg, this translates to approximately 10-30 grams daily (roughly 0.6-1.8 capfuls of the 17-gram dose) 2
• Dosing can be adjusted based on response, with the goal of achieving regular, soft bowel movements without diarrhea 2
• The medication can be titrated upward if constipation persists, though some children may remain constipated even at higher doses 2

Safety Profile in Children

PEG 3350 demonstrates excellent safety and tolerability in pediatric populations:

• Most common adverse effect: Diarrhea, reported in approximately 20% of patients (9 of 46 in one study) 2
• No serious adverse events reported in clinical trials 3
• Non-addictive and tasteless, improving compliance compared to other laxatives 2, 4
• Laboratory values (serum chemistry panels) remain stable during treatment 3

Clinical Efficacy

• Significant increase in bowel movement frequency (p = 0.0001) 2
• 88% of children achieved excellent/good bowel preparation for colonoscopy compared to 29% with senna (p = 0.0022) 3
• In children with dysfunctional elimination: 39% became completely dry, 57% had decreased wetting, and only 4% showed no improvement 2
• Improved voiding parameters: increased voided volume (146 vs 210 mL, p <0.0001) and decreased post-void residual (92 vs 48 mL, p <0.0001) 2

Important Clinical Considerations

Common pitfalls to avoid:

• Duration limitation: The FDA label specifies maximum 7 days for over-the-counter use, though clinical practice often involves longer-term maintenance therapy under physician supervision 1, 4
• Persistent constipation: Children who remain constipated despite treatment have significantly higher post-void residuals and less improvement in symptoms 2
• Dose inadequacy: If constipation persists, the dose may need adjustment rather than switching medications, as the average dose in treatment failures (0.69 g/kg) did not differ significantly from successes (0.61 g/kg), suggesting individual variation 2

Role in Treatment Guidelines

• Consensus guidelines recommend osmotic laxatives like PEG 3350 as first-line maintenance treatment for pediatric functional constipation 4
• Should be used in conjunction with patient and parental education and behavioral training 4
• Particularly valuable for children who have failed or are intolerant of other pharmacotherapies 4