What is the appropriate dose of MiraLAX (polyethylene glycol 3350) for a child weighing 15.2 kg?

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MiraLAX Dosing for a 15.2 kg Child

For a child weighing 15.2 kg, administer approximately 12 grams of MiraLAX (polyethylene glycol 3350) daily, which equals roughly 3.5 to 4 leveled teaspoons or 1 leveled tablespoon plus 1 teaspoon.

Weight-Based Dosing Calculation

  • The optimal maintenance dose for children with constipation is 0.78 g/kg/day based on clinical studies in infants and young children 1
  • For a 15.2 kg child: 15.2 kg × 0.78 g/kg = 11.9 grams per day (approximately 12 grams) 1
  • This dose falls within the safe and effective range of 0.26-1.26 g/kg/day established in pediatric studies 1

Practical Measurement Using Household Devices

Using standard measuring spoons (most practical for home use):

  • 1 leveled teaspoon of MiraLAX = approximately 3.3 grams 2
  • 1 leveled tablespoon = approximately 10 grams 2
  • For 12 grams total: Use 1 leveled tablespoon (10 g) plus 1 leveled teaspoon (3.3 g) 2
  • Alternative: 3.5 to 4 leveled teaspoons (3.5 teaspoons = 11.6 g; 4 teaspoons = 13.2 g) 2

Using the manufacturer's cap:

  • The standard capful = 17 grams (adult dose) 2
  • For this child, use approximately 2/3 to 3/4 of a capful, though this method has more measurement variability 2

Critical Dosing Considerations

  • Always level the measuring device to improve consistency and reduce dose variability, which is particularly important for children sensitive to dosing changes 2
  • Use one dedicated measuring device throughout treatment rather than switching between different spoons or caps 2
  • A kitchen scale provides the most precise measurement (12 grams exactly), though most families will not have access to one 2

Administration Instructions

  • Mix the powder with any liquid (water, juice, milk) as MiraLAX is tasteless and dissolves completely 3
  • Administer once daily, typically in the morning 1
  • No specific timing with meals is required 1

Dose Adjustment Strategy

  • Start with the calculated dose of 12 grams daily 1
  • If constipation persists after 3-5 days, the dose may be increased up to 1.26 g/kg/day (19 grams for this child) 1
  • If diarrhea develops, reduce the dose by 25-50% and titrate upward more gradually 1
  • The goal is 1-2 soft, formed bowel movements daily without straining 3

Safety Profile for This Age Group

  • MiraLAX is safe and effective for children in this weight range with a 97.6% success rate in relieving constipation 1
  • The most common side effect is transient diarrhea (14% of patients), which resolves with dose adjustment 1
  • Increased gas may occur but is uncommon 1
  • Long-term use is safe, with children in studies treated for an average of 6.2 months (range 3 weeks to 21 months) 1

Common Pitfall to Avoid

Do not use "heaping" or unleveled measurements, as heaping tablespoons can contain up to 15 grams versus 10 grams when leveled—a 50% increase that may cause diarrhea 2. Consistency in measurement technique is essential for predictable therapeutic effect.

References

Research

Polyethylene glycol for constipation in children younger than eighteen months old.

Journal of pediatric gastroenterology and nutrition, 2004

Research

Measurement of Polyethylene Glycol 3350 With Standard Household Measuring Devices.

The journal of pediatric pharmacology and therapeutics : JPPT : the official journal of PPAG, 2024

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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