Recommended Dosage of Magnesium Oxide for Heartburn and Indigestion
For treating heartburn and indigestion, the recommended dosage of magnesium oxide is 400-500 mg daily, which can be taken as 1 tablet twice daily or as directed by a physician. 1, 2
Mechanism of Action and Formulation
- Magnesium oxide functions as an osmotic laxative and antacid that helps relieve heartburn and indigestion 1
- In the stomach, magnesium oxide is converted to magnesium chloride under acidic conditions, which neutralizes stomach acid 1, 3
- Magnesium oxide contains more elemental magnesium than other magnesium salts and is insoluble in water but soluble in dilute acid 1
Dosing Recommendations
- For antacid purposes (treating heartburn): Take 1 tablet (typically 400-500 mg) twice daily 2
- As a magnesium supplement: Take 1-2 tablets daily 2
- For constipation management: 400-500 mg daily, which may be increased if needed 1
- Evening dosing may be more effective as intestinal transit is slower at night, allowing more time for absorption 1
Efficacy for Gastrointestinal Symptoms
- Magnesium oxide effectively reduces symptoms of heartburn by neutralizing stomach acid 1
- It also helps relieve constipation, which can be associated with indigestion 4
- In clinical studies, magnesium oxide supplementation reduced gastrointestinal complications including nausea, vomiting, and constipation 4
Important Considerations and Precautions
- Avoid use in patients with renal insufficiency due to risk of hypermagnesemia 1
- Absorption may be reduced when taken with acid-suppressing medications like proton pump inhibitors (PPIs) or H2 receptor antagonists (H2RAs) 3
- If taking PPIs or H2RAs, a higher dose of magnesium oxide may be required for the same laxative effect 3
- Approximately 15% of orally administered magnesium oxide is absorbed into the bloodstream, with peak concentration occurring about 3 hours after administration 5
- Common side effects include diarrhea and abdominal discomfort, particularly at higher doses 1
Special Populations
- For elderly patients, start at the lower end of the dosing range and titrate as needed 1
- During pregnancy, use with caution and only as directed by a physician 1
- In patients with short bowel syndrome, magnesium oxide can be given as gelatin capsules of 4 mmol (160 mg) to a total of 12-24 mmol daily, usually at night 1
Alternative Formulations
- Other magnesium formulations (citrate, glycinate, lactate, etc.) have not been as extensively studied for heartburn and indigestion 1
- Pantoprazole magnesium and omeprazole magnesium are different medications that combine a proton pump inhibitor with magnesium and have shown efficacy in treating GERD symptoms 6, 7