Recommended Dosing for Magnesium Capsules
For general supplementation, magnesium oxide is typically given as 4 mmol (160 mg) capsules with a total daily dose of 12-24 mmol (480-960 mg elemental magnesium). 1
General Dosing Recommendations
- The Recommended Dietary Allowance (RDA) for magnesium is 320 mg/day for women and 420 mg/day for men 1
- Magnesium supplementation should not exceed the Tolerable Upper Intake Level of 350 mg/day from supplements to avoid adverse effects 1
- For oral magnesium oxide, which contains about 60% elemental magnesium, typical administration is as 4 mmol (160 mg) capsules 2
- Liquid or dissolvable forms are generally better tolerated than pills 1
Condition-Specific Dosing
- For chronic idiopathic constipation: Start with magnesium oxide 400-500 mg daily and titrate dose based on symptom response 1, 2
- For short bowel syndrome: 12-24 mmol daily (approximately 480-960 mg elemental magnesium), preferably administered at night when intestinal transit is slowest 1
- For erythromelalgia: Start at the RDA (320 mg for women; 420 mg for men) and increase gradually according to tolerance 1
Administration Considerations
- Administer magnesium at night when intestinal transit is slowest to improve absorption 1, 2
- Organic magnesium compounds (citrate, malate, acetyl taurate, glycinate) have better absorption than inorganic compounds 3
- Continuous-release formulations may improve bioavailability by providing magnesium release throughout the gastrointestinal tract 4
Monitoring and Safety Considerations
- Common side effects include diarrhea, abdominal distension, and gastrointestinal intolerance 1
- Avoid magnesium supplementation in patients with renal insufficiency due to risk of hypermagnesemia 1, 2
- Monitor for signs of magnesium toxicity, including hypotension, bradycardia, and respiratory depression 1
Special Considerations
- In patients with short bowel syndrome or significant GI disease, oral absorption may be compromised, requiring higher doses or parenteral administration 2
- For high-dose therapy, dividing the dose may improve tolerance but does not necessarily increase tissue magnesium levels 3
- For patients with refractory hypomagnesemia, oral 1-alpha hydroxy-cholecalciferol (0.25-9.00 μg daily) may improve magnesium balance, but requires monitoring of serum calcium 1