Pediatric Dosing of MiraLAX (Polyethylene Glycol 3350)

Bowel Preparation

For bowel preparation in children, a dose of 1.5 g/kg/day for 4 days before the procedure is recommended, with a clear liquid diet on day 4, as suggested by the American Gastroenterological Association 1, 2
Alternative 1-day preparations are also effective, though less studied, according to the American Gastroenterological Association 1, 2

The American Academy of Pediatrics recommends mixing the powder in at least 4-8 ounces of liquid, with acceptable liquids including water, juice, coffee, or tea 3
Juices with sorbitol content provide a synergistic osmotic effect, as noted by the American Academy of Pediatrics 3
Insufficient liquid volume is a common cause of treatment failure, as highlighted by the American Academy of Pediatrics 3

Response to treatment is durable over 6 months in adults, suggesting similar long-term efficacy in children, according to the American Gastroenterological Association 4
Continue maintenance dosing once bowel movements normalize rather than stopping abruptly, as recommended by the American Academy of Pediatrics 5

Abdominal distension, flatulence, and nausea may occur but are generally mild, as reported by the American Gastroenterological Association 4
Rule out bowel obstruction or paralytic ileus before initiating therapy, as cautioned by the American Academy of Pediatrics 5
Check for fecal impaction, which may require manual disimpaction or enema first, as advised by the American Academy of Pediatrics 5
Ensure adequate daily fluid intake beyond just the mixing liquid, as PEG requires water to work osmotically, as emphasized by the American Academy of Pediatrics 3

If there is no bowel movement after 3-4 days, add bisacodyl suppository (10mg) or glycerin suppository while continuing PEG, as recommended by the American Academy of Pediatrics 5
For persistent constipation, consider adding oral stimulant laxative (senna or bisacodyl) to PEG regimen, as suggested by the American Academy of Pediatrics 5

Inadequate liquid volume can reduce efficacy significantly, as warned by the American Academy of Pediatrics 3
Not confirming adequate fluid intake can lead to treatment failure, as noted by the American Academy of Pediatrics 3
Assuming treatment failure without first optimizing dose and ensuring compliance can lead to premature discontinuation, as cautioned by the American Academy of Pediatrics 5
Delaying rectal intervention beyond 3-4 days increases the risk of fecal impaction, as highlighted by the American Academy of Pediatrics 5

The American Urological Association recommends addressing underlying constipation with dietary modifications, such as increased fluids and fiber, if adequate fluid intake is ensured 6
Regular toileting habits, especially after meals, are encouraged to help manage constipation 6

The American Gastroenterological Association suggests that polyethylene glycol (PEG) has demonstrated durable efficacy for up to 6 months of continuous use in adults with chronic idiopathic constipation, implying similar long-term efficacy in children 7, 8

The average effective dose of PEG at long term is 0.7-0.8 g/kg/day, allowing for gradual reduction once response is established, as supported by evidence from pediatric studies 7, 8
PEG has been shown to be effective and safe for use in children for 6-12 months or more, with an average treatment duration of 8.4 months in pediatric studies 7, 8

Adding an oral stimulant laxative (e.g., senna or bisacodyl) to polyethylene glycol (PEG) therapy improves treatment success in children with refractory constipation compared with PEG alone. [9][10]
Administering stimulant laxatives approximately 30 minutes after meals enhances their efficacy by exploiting the gastro‑colonic reflex. 9

Magnesium oxide may be used as an alternative osmotic laxative when PEG is ineffective or not tolerated; however, pediatric evidence for its efficacy is limited. 10

Common adverse effects of PEG therapy—such as mild abdominal distension, flatulence, and nausea—are generally dose‑dependent and tend to be mild. 11