Magnesium Citrate Dosing for Pediatric Constipation
For pediatric patients with constipation, magnesium citrate should be dosed according to age: children 2-5 years should receive 2-3 fl oz, children 6-11 years should receive 3-7 fl oz (maximum 7 fl oz/24 hours), and children 12 years and older should receive 6.5-10 fl oz (maximum 10 fl oz/24 hours). 1
Age-Based Dosing Recommendations
The FDA-approved dosing for magnesium citrate in pediatric patients is as follows:
- Children under 2 years: Consult a doctor (not recommended without medical supervision)
- Children 2 to under 6 years: 2-3 fl oz per 24 hours (maximum 3 fl oz in 24 hours)
- Children 6 to under 12 years: 3-7 fl oz (maximum 7 fl oz in 24 hours)
- Children 12 years and older: 6.5-10 fl oz (maximum 10 fl oz in 24 hours) 1
Administration Guidelines
- Shake the bottle well before using
- Have the child drink a full glass (8 ounces) of liquid with each dose
- May be given as a single daily dose or in divided doses
- Ensure adequate hydration during treatment 1
Efficacy and Safety Considerations
Magnesium citrate works as an osmotic laxative by retaining fluids in the colon, which helps soften stool and stimulate bowel movements. Studies have shown that magnesium-based preparations are effective for treating constipation in children 2.
Safety Precautions
- Avoid in children with renal insufficiency: Magnesium-based preparations should not be used in patients with creatinine clearance <20 mg/dL due to risk of hypermagnesemia 3
- Rule out intestinal obstruction before initiating treatment 3
- Monitor for dehydration: Ensure adequate fluid intake when using magnesium laxatives 4
Alternative Options for Special Situations
For children who cannot tolerate magnesium citrate or have contraindications:
- PEG-3350 is an effective alternative, administered at a dose of 1.5 g/kg/day for 4 days before procedures requiring bowel cleansing, with a clear liquid diet on the fourth day 4
- One-day PEG-3350 preparations have also shown effectiveness 4
- For infants with normal or frequent bowel movements, clear liquids for 24 hours along with normal saline enema (10 mL/kg) may be sufficient 4
Comparative Efficacy
A retrospective study comparing magnesium citrate with polyethylene glycol-electrolyte solution (PEG-ELS) for fecal disimpaction found:
- Both methods took approximately the same amount of time for disimpaction (5.5 hours for magnesium citrate vs. 5.25 hours for PEG-ELS)
- Magnesium citrate was less invasive and less costly than nasogastric PEG-ELS
- However, about 12% of children were unable to drink the entire magnesium citrate dose due to taste issues 5
Practical Considerations
- For colonoscopy preparation in children, sodium picosulfate plus magnesium citrate (SPMC) in a split-dose regimen has shown superior bowel cleansing and better acceptability compared to day-before regimens 6
- For chronic constipation, magnesium oxide at 125 mg three times daily (for children <20 kg) or 250 mg three times daily (for children >20 kg) has shown effectiveness 2
Remember that maintenance of adequate hydration during treatment is particularly important in children, and selection of bowel preparation regimens should consider the patient's age, clinical state, and ability to comply with the medication regimen 4.