What is the recommended dose of MiraLAX (polyethylene glycol) for a 17-month-old child with constipation?

MiraLAX Dosing for 17-Month-Old with Constipation

For a 17-month-old child with constipation, start polyethylene glycol (MiraLAX) at approximately 0.8 g/kg/day (roughly 8-10 grams or half a capful daily for an average-sized toddler), mixed in 4-8 ounces of any beverage, and titrate based on response. 1

Evidence-Based Dosing for Infants Under 18 Months

Initial and Maintenance Dosing

• Start with 0.88 g/kg/day as the mean initial dose demonstrated in infants younger than 18 months 1
• Effective maintenance dose averages 0.78 g/kg/day (range 0.26-1.26 g/kg/day) in this age group 1
• For practical application: A 17-month-old weighing approximately 11-12 kg would receive roughly 8-10 grams daily (about half of the standard 17-gram adult capful) 1

Safety and Efficacy Profile

• Polyethylene glycol relieved constipation in 97.6% of infants under 18 months in clinical studies 1
• The safety profile in infants mirrors that of older children, with minimal side effects 1
• Mean duration of successful therapy was 6.2 months (range 3 weeks to 21 months) in the infant population 1

Administration Guidelines

Preparation and Delivery

• Mix the powder completely in 4-8 ounces of any beverage (cold, hot, or room temperature) 2
• Ensure powder is fully dissolved before giving—do not administer if clumps remain 2
• Do not combine with starch-based thickeners 2
• The medication is tasteless and can be mixed with any liquid the child will drink 3

Dose Titration Strategy

• Titrate upward gradually if constipation persists, based on symptom response and side effects 4
• Allow 24-48 hours (or longer) before increasing the dose, as improvement may be delayed 4
• Adjust downward if diarrhea develops 1

Expected Side Effects and Monitoring

Common Adverse Effects

• Transient diarrhea is the most common side effect, occurring in approximately 14% of infants, and resolves with dose adjustment 1
• Increased gas per rectum may occur but is generally mild 1
• Bloating and flatulence are dose-dependent but may be difficult to assess in preverbal children—careful parental observation is essential 4

Important Safety Considerations

• No clinically significant side effects or loss of efficacy occur with long-term use 5
• The medication is non-addictive 6
• Ensure adequate hydration while using polyethylene glycol 4

Critical Caveats

FDA Labeling Limitation

• The FDA label states "children 16 years of age or under: ask a doctor" 2, but extensive pediatric research demonstrates safety and efficacy in infants as young as birth 1
• This represents a labeling-practice gap where clinical evidence supports use in younger children despite conservative FDA language 1

When to Reassess

• If constipation persists despite adequate dosing (approaching 1.26 g/kg/day), consider that the child may have refractory constipation requiring additional evaluation 1
• Persistent constipation despite treatment is associated with worse outcomes and may indicate need for specialist referral 6

Adjunctive Measures

• Always address underlying constipation triggers: ensure adequate fluid intake, encourage physical activity, and treat any dietary factors 7
• Goal is one soft, non-forced bowel movement every 1-2 days 7
• Consider adding behavioral interventions and scheduled toilet sitting (though limited at this age) 7