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Magnesium Hydroxide

Drug Information

Magnesium hydroxide is used as an antacid for short-term relief of stomach upset and as a laxative for short-term treatment of constipation. Magnesium hydroxide is available in nonprescription products alone and in combination with other nonprescription ingredients to relieve stomach upset.

Common brand names:

Phillips Milk of Magnesia

Summary of Interactions with Vitamins, Herbs, & Foods

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Folic Acid

    Folic acid is needed by the body to utilize vitamin B12. Antacids, including magnesium hydroxide, inhibit folic acid absorption. People taking antacids are advised to supplement with folic acid.

  • Iron

    Antacids, including magnesium hydroxide, may reduce the absorption of dietary iron. Iron supplements do not require stomach acid for absorption and one human study found that a magnesium hydroxide/aluminum hydroxide antacid did not decrease supplemental iron absorption.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Reduce Side Effects

  • none

Support Medicine

  • none

Reduces Effectiveness

  • none

Potential Negative Interaction

  • none

Explanation Required 

  • Potassium

    Individuals taking potassium-depleting diuretics and those who are otherwise at risk of developing potassium deficiency (such as people with chronic diarrhea or vomiting) may experience a fall in serum potassium levels if they take magnesium without taking additional potassium. This could lead to muscle cramps or, in individuals taking digoxin or digitalis, more serious problems such as cardiac arrhythmias. Individuals who have a history of potassium deficiency and those who are at risk of developing potassium deficiency, as well as people taking digoxin or digitalis, should consult a physician before taking magnesium-containing products.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

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