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Magnesium Oxide vs. Magnesium Hydroxide: What's the Difference?

Edited by Aimie Carlson || By Janet White || Published on December 21, 2023
Magnesium oxide is a compound of magnesium and oxygen (MgO), while magnesium hydroxide contains magnesium, oxygen, and hydrogen (Mg(OH)₂), commonly used as an antacid.

Key Differences

Magnesium oxide (MgO) is a simple oxide of magnesium, formed by the combination of magnesium with oxygen. Magnesium hydroxide (Mg(OH)₂), on the other hand, is a compound consisting of magnesium, oxygen, and hydrogen.
Magnesium oxide is often used as a refractory material due to its high melting point and as a supplement for magnesium deficiency. Magnesium hydroxide is widely known as an antacid and laxative, providing relief from acidity and constipation.
The production of magnesium oxide typically involves the calcination of magnesium carbonate or magnesium hydroxide. In contrast, magnesium hydroxide is usually obtained by mixing a soluble magnesium salt with sodium hydroxide.
In terms of chemical properties, magnesium oxide is a basic oxide and reacts with acids to form salts. Magnesium hydroxide, being a hydroxide, also exhibits basic properties and neutralizes stomach acid effectively.
Magnesium oxide has applications in agriculture as a soil additive and in environmental technology for water treatment. Magnesium hydroxide is used in pharmaceuticals and also as a flame retardant in various materials.

Comparison Chart

Chemical Composition

Magnesium and oxygen (MgO)
Magnesium, oxygen, and hydrogen (Mg(OH)₂)

Common Uses

Supplement, refractory material
Antacid, laxative

Production Method

Calcination of magnesium carbonate
Mixing magnesium salt with sodium hydroxide

Chemical Properties

Basic oxide, reacts with acids
Basic, neutralizes stomach acid


Soil additive, water treatment
Pharmaceuticals, flame retardant

Magnesium Oxide and Magnesium Hydroxide Definitions

Magnesium Oxide

Magnesium oxide is utilized in water treatment
Water treatment facilities use magnesium oxide for removing heavy metals.

Magnesium Hydroxide

It acts as a laxative for constipation relief
Magnesium hydroxide can be used to treat occasional constipation.

Magnesium Oxide

It's a basic oxide reacting with acids to form salts
Magnesium oxide neutralizes acid in industrial processes.

Magnesium Hydroxide

It's produced by reacting magnesium salts with sodium hydroxide
Magnesium hydroxide is synthesized for medical use.

Magnesium Oxide

Magnesium oxide serves as a refractory material
Refractory bricks often contain magnesium oxide for high-temperature resistance.

Magnesium Hydroxide

Magnesium hydroxide is an antacid relieving stomach acidity
He took magnesium hydroxide to ease his heartburn.

Magnesium Oxide

It's used in agriculture to amend acidic soils
Farmers use magnesium oxide to balance the pH of their soil.

Magnesium Hydroxide

Magnesium hydroxide is used in flame retardants
Many plastics include magnesium hydroxide for fire resistance.

Magnesium Oxide

Magnesium oxide is a white powder used as a supplement
She took magnesium oxide for her magnesium deficiency.

Magnesium Hydroxide

Magnesium hydroxide is effective in wastewater treatment
The plant uses magnesium hydroxide for neutralizing acidic waste.


Can magnesium hydroxide relieve stomach acidity?

Yes, it's an effective antacid.

What is magnesium hydroxide used for?

Mainly as an antacid and laxative, but also in flame retardants.

Is magnesium hydroxide used in flame retardants?

Yes, it's added to materials to enhance fire resistance.

What is magnesium oxide?

A compound of magnesium and oxygen, used as a supplement and in industrial processes.

Is magnesium oxide used in agriculture?

Yes, as a soil additive to correct acidity.

What makes magnesium hydroxide a good laxative?

It draws water into the intestines, easing bowel movements.

Can magnesium oxide be used for water treatment?

Yes, for removing heavy metals and adjusting pH.

Is magnesium oxide a refractory material?

Yes, due to its high melting point.

What industries use magnesium hydroxide?

Pharmaceuticals, wastewater treatment, and materials manufacturing.

How is magnesium oxide produced?

Typically by calcining magnesium carbonate or magnesium hydroxide.

Does magnesium oxide react with acids?

Yes, forming salts.

How is magnesium hydroxide produced?

By reacting a soluble magnesium salt with sodium hydroxide.

Why is magnesium hydroxide added to plastics?

For its fire-retardant properties.

Can magnesium oxide be used in industrial processes?

Yes, especially where acid neutralization is required.

Can magnesium hydroxide treat constipation?

Yes, as a mild laxative.

What are the medical uses of magnesium oxide?

Primarily as a dietary supplement for magnesium deficiency.

Is magnesium oxide safe for consumption?

Yes, when used as directed in supplements.

How does magnesium hydroxide work as an antacid?

It neutralizes stomach acid.

Is magnesium hydroxide effective in wastewater treatment?

Yes, it helps neutralize acidic waste.

What are the environmental applications of magnesium oxide?

In water treatment and soil pH adjustment.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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