From the Guidelines
Magnesium oxide should be started at a lower dose, which may be increased if necessary, for the treatment of constipation in adults, as recommended by the American Gastroenterological Association-American College of Gastroenterology clinical practice guideline 1.
Key Considerations
- The dose of magnesium oxide can be adjusted based on individual response, but it is essential to avoid use in patients with renal insufficiency due to the risk of hypermagnesemia 1.
- The trials were conducted for 4 weeks, although longer-term use is probably appropriate, and the panel suggests starting at a lower dose, which may be increased if necessary 1.
- It is crucial to maintain adequate hydration throughout the day for best results, as magnesium oxide works by drawing water into the intestines, softening stool, and stimulating bowel movements.
Important Points to Note
- Magnesium oxide is recommended for adults with chronic idiopathic constipation (CIC) over management without magnesium oxide, with a conditional recommendation and very low certainty of evidence 1.
- The use of magnesium oxide should be considered after assessing the patient's renal function and other medical conditions that may interact with the medication.
- Patients should be informed about the potential side effects, including abdominal cramping, nausea, or diarrhea, and advised to seek medical attention if constipation persists beyond 7 days of treatment or recurs frequently.
From the FDA Drug Label
DIRECTIONS Antacid Directions:■ take 1 tablet twice a day or as directed by a physician Magnesium Supplement Directions: ■take 1 to 2 tablets daily or as directed by a physician The recommended dose of magnesium oxide for constipation is not explicitly stated in the provided drug labels. However, based on the Magnesium Supplement Directions, the dose is 1 to 2 tablets daily. Since each tablet contains 400mg of Magnesium Oxide (241.2mg elemental magnesium) 2, the dose for constipation would be 400mg to 800mg of Magnesium Oxide (241.2mg to 482.4mg elemental magnesium) daily.
- The dose may vary depending on the individual's needs and the direction of a physician.
- It is essential to follow the directions of a physician for the correct dosage. 2
From the Research
Magnesium Oxide Dosage for Constipation
- The optimal dosage of magnesium oxide for constipation is not explicitly stated in the provided studies, but the doses used in the studies range from 1.0 g to 1.5 g per day 3, 4.
- A study published in 2021 found that reducing the number of daily doses of magnesium oxide from three to two, or from two to one, did not affect its laxative action, suggesting that the total daily dose may be more important than the frequency of dosing 5.
- Another study published in 2021 compared the efficacy of magnesium oxide (1.5 g) with senna (1.0 g) and placebo for the treatment of chronic constipation, and found that both magnesium oxide and senna significantly improved symptoms of constipation compared to placebo 4.
- A study published in 2012 used a dose of 1 g of magnesium oxide every 12 hours, but found that it did not enhance the recovery of gastrointestinal function after open colonic surgery 6.
Dosage Considerations
- The studies suggest that the dose of magnesium oxide used for constipation can vary, and that the optimal dose may depend on individual factors such as the severity of constipation and the presence of other medical conditions 3, 4.
- It is also important to consider the potential for side effects, especially in the elderly and in patients with renal impairment, when using magnesium oxide for constipation 3.