Magnesium Citrate Dosing for Children
For oral magnesium citrate as a laxative/bowel cleanser, use age-based dosing: children 6 to under 12 years receive 3 to 7 fl oz (maximum 7 fl oz in 24 hours), children 2 to under 6 years receive 2 to 3 fl oz (maximum 3 fl oz in 24 hours), and children under 2 years require physician consultation before administration. 1
Age-Based Dosing for Oral Magnesium Citrate (Laxative/Bowel Preparation)
The FDA-approved dosing for oral magnesium citrate solution varies by age 1:
- Children 6 to under 12 years: 3 to 7 fl oz per dose, with a maximum of 7 fl oz in 24 hours 1
- Children 2 to under 6 years: 2 to 3 fl oz in 24 hours, with a maximum of 3 fl oz in 24 hours 1
- Children under 2 years: Consult a physician before use 1
- Children 12 years and older: 6.5 to 10 fl oz, with a maximum of 10 fl oz in 24 hours 1
Administration considerations: Each dose should be accompanied by a full glass (8 ounces) of liquid, and the bottle must be shaken well before use 1. The dose may be given as a single daily dose or divided doses 1.
Parenteral Magnesium Dosing (When Oral Route Not Appropriate)
For children requiring parenteral magnesium supplementation in the context of parenteral nutrition, the ESPGHAN/ESPEN guidelines provide weight-based recommendations 2:
- Preterm infants (first days of life): 0.1-0.2 mmol/kg/day (2.5-5.0 mg/kg/day) 2
- Growing premature infants: 0.2-0.3 mmol/kg/day (5.0-7.5 mg/kg/day) 2
- Infants 0-6 months: 0.1-0.2 mmol/kg/day (2.4-5 mg/kg/day) 2
- Infants 7-12 months: 0.15 mmol/kg/day (4 mg/kg/day) 2
- Children 1-18 years: 0.1 mmol/kg/day (2.4 mg/kg/day) 2
Special Clinical Situations
Magnesium Deficiency Treatment
For therapeutic magnesium supplementation in deficiency states, research supports higher oral doses. A parenteral dose of 0.1 mL/kg/day of 50% magnesium sulfate (approximately 0.2 mmol/kg/day or 0.4 mEq/kg/day) may be given for 5 days 3. For oral therapy, 1.0 mL/kg/day of 10% magnesium chloride (0.5 mmol/kg/day) may be administered for extended periods 3.
High-dose oral magnesium citrate has been successfully used in primary hypomagnesemia, with doses reaching up to 90 mg/kg/day of elemental magnesium citrate without gastrointestinal side effects 4. This demonstrates that magnesium citrate is better tolerated than other magnesium salts at high doses 4.
Preterm Infants with Maternal Magnesium Exposure
Critical caveat: In preterm infants whose mothers received magnesium sulfate therapy (for preeclampsia or tocolysis), magnesium intakes must be adapted to postnatal blood concentrations due to elevated magnesium levels and limited renal excretion capacity in the first week of life 2.
Cathartic Use in Toxic Ingestions
For gastrointestinal decontamination following toxic ingestion, magnesium citrate 4 mL/kg of a 6% solution significantly reduces transit time of activated charcoal compared to no cathartic (13.0 hours vs 19.5 hours) 5. Higher doses (6-8 mL/kg) provide similar efficacy 5.
Important Safety Considerations
- Monitoring requirements: Regular monitoring of serum magnesium, calcium, and potassium levels is essential during magnesium therapy 3
- Renal function: Hypermagnesemia risk increases with inadequate renal function 3
- Hydration: Magnesium citrate has a dehydrating effect; ensure adequate fluid intake 6
- Bioavailability: Organic magnesium compounds (including magnesium citrate) demonstrate superior absorption compared to inorganic compounds 7