Maximum Recommended Daily Dose of Magnesium
The maximum recommended daily dose of elemental magnesium should not exceed 350 mg for women and 420 mg for men according to current clinical guidelines. 1
Recommended Dosing by Population
General Population
- Adult women: 350 mg/day maximum 1
- Adult men: 420 mg/day maximum 1
- These doses represent the upper limit for routine supplementation
Therapeutic Dosing
- For hypomagnesemia: 500 mg to 1 g daily, which can be increased with monitoring 1
- For constipation (as a laxative): Maximum 60 mL of magnesium-containing solution in a 24-hour period 2
Special Populations
- Parenteral nutrition:
Absorption and Administration Considerations
- Smaller, divided doses throughout the day improve relative absorption compared to a single large dose 1
- Taking magnesium at night when intestinal transit is slower may improve absorption 1
- Liquid or dissolvable magnesium products are usually better tolerated than pills 3
Monitoring and Safety
Signs of Excess
- Gastrointestinal symptoms (diarrhea is most common)
- Muscle weakness
- Flushing
- Hypotension
- Bradycardia
- Blurred vision
- Cognitive effects 3
Contraindications
- Significant renal impairment (creatinine clearance <20 mg/dL) 1
- Patients with cholestasis receiving parenteral nutrition should have manganese discontinued 3
Clinical Pearls
- Urinary magnesium excretion of <80 mg/day may indicate deficiency 4
- Serum magnesium <0.85 mmol/L (2.06 mg/dL) may indicate deficiency, even when within the "normal" laboratory range 4
- A calcium-to-magnesium ratio between 1.70-2.60 is considered optimal; many Americans have ratios >3.0, which may warrant magnesium supplementation 5
- 68% of US adults consume less than the recommended daily allowance of magnesium 6
Formulation Selection
- Magnesium glycinate: Recommended for patients with sleep disorders (500 mg before bedtime) 1
- Magnesium oxide: 400-500 mg daily recommended for chronic idiopathic constipation 1
When prescribing magnesium, always consider the patient's renal function, concurrent medications, and monitor for gastrointestinal side effects, which are the most common limiting factor in oral supplementation.