Magnesium hydroxide is an inorganic compound used as a laxative and antacid. It is naturally found as the mineral brucite.
- Mechanism
- Curator reviewed
The suspension of magnesium hydroxide is ingested and enters the stomach. According to the amount ingested, the magnesium hydroxide will either act as an antacid or a laxative.
Through the ingestion of 0.5-1.5 grams (in adults) the magnesium hydroxide will act by simple acid neutralization in the stomach. The hydroxide ions from the magnesium hydroxide suspension will combine with the acidic H+ ions of the hydrochloric acid made by the stomachs parietal cells. This neutralization reaction will result in the formation of magnesium chloride and water.
Through the ingestion of 2-5 grams (in adults) the magnesium hydroxide acts as a laxative in the colon. The majority of the suspension is not absorbed in the intestinal tract and will create an osmotic effect to draw water into the gut from surrounding tissues. With this increase of water in the intestines, the feces will soften and the intraluminal volume of the feces will increase. These effects still stimulate intestinal motility and induce the urge to defecate. Magnesium hydroxide will also release cholecystokinin (CCK) in the intestines which will accumulate water and electrolytes in the lumen and furthermore increase intestinal motility.
- Primary indication
- Magnesium hydroxide can be used as an antacid or a laxative depending on the administered dose.Curator reviewed · 16 structured indications
- Formula / weight
- H2MgO2 · 58.32 g/mol (avg)
- First approval
- Canada, 1997 · United States, 2000
- Also known as
- Magnesium dihydroxide · Milk of magnesia
- Code names
- E-528 · INS-528 · INS NO.528
- Brand names
Resolves to
VTHJTEIRLNZDEV-UHFFFAOYSA-LSMILES[OH-].[OH-].[Mg++]What you can answer from here — as of September 23, 2026
Which drugs share a target with Magnesium hydroxide, and which of those have an active Phase 3 trial?
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