MiraLAX Dosing for a 20-Month-Old Constipated Child
For a 20-month-old male weighing 10.7 kg with constipation, start with 8.3 grams of MiraLAX (polyethylene glycol 3350) daily, which can be titrated up to a maximum of approximately 13.5 grams daily based on response. 1
Recommended Dosing Strategy
Initial Dose
- Start with 0.78 g/kg/day, which equals approximately 8.3 grams daily for this 10.7 kg child 1
- This can be given as one dose mixed in 4-8 ounces of liquid (water, juice, or milk) 1
- The powder is tasteless and dissolves completely, making it well-tolerated by young children 2
Dose Titration
- Adjust based on stool consistency and frequency over 3-7 days 1
- The effective maintenance dose range in children under 18 months is 0.26-1.26 g/kg/day 1
- For this child, the maximum dose would be approximately 13.5 grams daily (1.26 g/kg × 10.7 kg) 1
- If diarrhea occurs, reduce the dose; if constipation persists, increase gradually 1
Safety Profile for Young Children
Evidence in This Age Group
- PEG 3350 is safe and effective in children younger than 18 months, with a 97.6% success rate in relieving constipation 1
- The safety and dosing profile for infants is similar to that reported in older children 1
- International guidelines recommend PEG as the first-choice laxative for functional constipation in children 3
Monitoring Considerations
- Monitor for transient diarrhea, which may occur but typically resolves with dose adjustment 1
- In patients predisposed to water and electrolyte imbalances, consider monitoring serum electrolytes, though this is rarely necessary in otherwise healthy children 3
- Increased gas per rectum may occur but is generally mild 1
Expected Response Timeline
- Most children respond within the first week of treatment, though optimal efficacy may take up to 2 weeks 3, 4
- Mean duration of therapy in the studied population was 6.2 months, indicating PEG is safe for long-term use 1
- No loss of efficacy occurs with prolonged use 2
Important Clinical Pearls
- PEG acts as an osmotic laxative with dose-dependent efficacy 3
- The medication has no taste, which significantly improves compliance compared to alternatives like milk of magnesia 2
- No clinically significant side effects have been reported at therapeutic doses in young children 1, 2
- Ensure adequate fluid intake as this enhances the osmotic effect 5