What form of magnesium is best at raising blood magnesium levels without causing diarrhea, given intolerance to magnesium sucrisomal, glycinate, citrate, and malate?

Magnesium Chloride or Intravenous/Subcutaneous Magnesium

For patients who cannot tolerate oral magnesium formulations without developing loose stools, magnesium chloride capsules (specifically magnesium oxide converted to magnesium chloride in the stomach) or parenteral magnesium administration are the best options for raising blood magnesium levels. 1

Why Standard Oral Forms Cause Diarrhea

All the magnesium forms you've tried (sucrosomal, glycinate, citrate, malate) cause loose stools through osmotic effects—they draw water into the intestines, which is actually the mechanism by which most magnesium supplements work as laxatives. 1, 2 The citrate and malate forms create particularly strong osmotic gradients, making diarrhea more pronounced. 2

The Magnesium Oxide/Chloride Strategy

Magnesium oxide given as gelatin capsules at night represents the best oral option for your situation. 1 Here's why this works differently:

• Magnesium oxide is insoluble in water and alcohol but dissolves in stomach acid to form magnesium chloride 1
• When given at night in capsule form (not liquid), intestinal transit is slower, allowing more time for absorption before reaching the colon 1
• The typical dose is 4 mmol magnesium oxide (160 mg MgO) capsules, totaling 12-24 mmol daily, all taken at bedtime 1
• This formulation contains more elemental magnesium than other salts while minimizing the osmotic diarrhea effect 1

The key difference from what you've tried: You need gelatin capsules of magnesium oxide taken specifically at night, not magnesium oxide tablets or liquids taken during the day. 1

When Oral Magnesium Fails Completely

If even nighttime magnesium oxide capsules cause loose stools, parenteral administration becomes necessary:

• Subcutaneous saline with magnesium: 0.5-1 liter of saline with 4 mmol magnesium sulfate added, given 1-3 times weekly 1
• Intravenous magnesium: Through a central line if needed more frequently than 3 times weekly 1
• This bypasses the GI tract entirely, eliminating diarrhea while effectively raising blood magnesium levels 1

Critical First Step: Rule Out Secondary Hyperaldosteronism

Before aggressive magnesium supplementation, ensure adequate hydration and sodium repletion. 1 Water and sodium depletion causes secondary hyperaldosteronism, which increases urinary magnesium losses. Correcting this is the most important first step and may reduce your magnesium requirements. 1

Adjunctive Strategy: Vitamin D Analog

If oral magnesium continues to fail despite the above measures, oral 1-alpha hydroxycholecalciferol (0.25-9.00 mcg daily, gradually increased every 2-4 weeks) can improve magnesium balance. 1 However, this requires regular serum calcium monitoring to avoid hypercalcemia. 1

Safety Precautions

• Avoid all magnesium supplementation if your creatinine clearance is <20 mL/min due to hypermagnesemia risk 1, 2
• Monitor calcium levels if using vitamin D analogs 1
• Reduce dietary fat intake, as excess lipid can worsen magnesium absorption 1

Practical Algorithm

1. First: Ensure adequate hydration and sodium intake to correct secondary hyperaldosteronism 1
2. Second: Try magnesium oxide 12-24 mmol (as gelatin capsules) taken entirely at bedtime 1
3. Third: If diarrhea persists, add 1-alpha hydroxycholecalciferol 0.25 mcg daily, increasing gradually with calcium monitoring 1
4. Fourth: If still unsuccessful, transition to subcutaneous saline with 4 mmol magnesium sulfate 1-3 times weekly 1
5. Fifth: If more frequent dosing needed, use intravenous magnesium through a central line 1

Why Sucrosomal Magnesium Failed Despite Marketing Claims

While one study suggested sucrosomal magnesium has higher bioavailability than magnesium oxide 3, it still causes GI side effects in sensitive patients because any absorbed magnesium that isn't taken up by cells will be excreted into the intestinal lumen, creating osmotic diarrhea. The issue isn't bioavailability—it's your intestinal sensitivity to osmotic effects.