Magnesium hydroxide

E number E528INS 528CAS 1309-42-8

Used as a colour — Codex also lists it as acidity regulator, retention agent.

Magnesium hydroxide is an alkaline acidity regulator and anticaking agent, used in canned goods and powdered products.

Where it is and isn’t permitted

Status of Magnesium hydroxide by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
United StatesFood and Drug AdministrationPermitted21 CFR 184.1428retrieved 2026-09-07
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

9 food categories

no numerical limit (good manufacturing practice)

Show every food category
  • 01.1.3 Fluid Buttermilk (plain) — GMP
  • 01.2.1.2 Fermented milks (plain), heat-treated after fermentation — GMP
  • 09.2.2 Frozen battered fish, fish fillets and fish products, including molluscs, crustaceans, and echinoderms — GMP
  • 09.2.3 Frozen minced and creamed fish products, including molluscs, crustaceans, and echinoderms — GMP
  • 09.2.4 Cooked and/or fried fish and fish products, including molluscs, crustaceans, and echinoderms — GMP
  • 09.2.5 Smoked, dried, fermented, and/or salted fish and fish products, including molluscs, crustaceans, and echinoderms — GMP
  • 11.4 Other sugars and syrups (e.g. xylose, maple syrup, sugar toppings) — GMP
  • 12.1.2 Salt substitutes — GMP
  • 14.1.5 Coffee, coffee substitutes, tea, herbal infusions, and other hot cereal and grain beverages, excluding cocoa — GMP
CXS 192-1995 Table Three, INS 528and 9 further provisionsretrieved 2026-09-07

What it is made from

Precipitated from seawater or magnesium salt solutions with an alkali.

  • Vegan
  • Vegetarian
CAS registry number
1309-42-8
InChIKey
VTHJTEIRLNZDEV-UHFFFAOYSA-L
PubChem
CID 73981

Every name it appears under

65 recorded names. A label may use any of them.

E number

  • E528

INS number

  • 528

CAS registry number

  • 1309-42-8

As it appears in regulation

  • Magnesium hydroxide

Other names

  • Alcanex NHC 25
  • Antacid-Laxative
  • Baschem 12
  • CareOne Milk of Magnesia Cherry
  • Careone Milk of magnesia Original
  • Careone Milk of magnesia Original Milk of Magnesia Original
  • Caustic magnesite
  • Childrens Oral Saline Laxative
  • CVS Health Childrens
  • CVS Health Childrens Saline Laxative
  • CVS Magnesium Hydroxide Laxative Chew
  • Dulcolax Chewy Bites Assorted Fruits
  • Dulcolax Chewy Fruit Bites Cherry Berry
  • Dulcolax Liquid
  • Dulcolax Soft Chews Mixed Berry
  • Dulcolax Soft Chews Watermelon
  • E 528
  • Equate Gentle Laxative Soft chew
  • Equate Kids Gentle Laxative SC
  • Gentle Laxative
  • Humco Milk Of Magnesia
  • Hydrate, Magnesium
  • Hydroxide, Magnesium
  • INS NO.528
  • INS-528
  • LAXADE
  • MagLax
  • Magmex
  • Magmilax Powder
  • MAGNALAX
  • Magnesii hydroxidum
  • Magnesium (as hydroxide)
  • Magnesium dihydroxide
  • Magnesium hydrate
  • Magnesium hydroxide
  • Magnesium hydroxide (Mg(OH)2)
  • Magnesium(II) hydroxide
  • Medibest Milk of Magnesia
  • Meijer Magnesium Hydroxide Laxative Soft Chew
  • Milk of magnesia
  • Milk Of Magnesia Cherry
  • Milk of Magnesia Concentrate
  • Milk Of Magnesia Liquid
  • Milk Of Magnesia Mint
  • Milk Of Magnesia Original
  • MiraFAST soft chews
  • MVT Powder
  • NBZ3QY004S
  • Phillips Fresh Mint Milk Of Magnesia
  • Phillips magnesia tablets
  • Phillips milk of magnesia liquid
  • Phillips Milk Of Magnesia Wild Cherry
  • Phillips Original Milk Of Magnesia
  • Premier Value Milk of Magnesia
  • Sunmark Milk Of Magnesia
  • Sunmark Milk Of Magnesia Mint
  • SUNMARK MILK OF MAGNESIA ORIGINAL
  • Walgreens Blueberry Raspberry Gentle Laxative
  • Walgreens Childrens
  • Walgreens Childrens Saline Laxative

Systematic names

  • Magnesium dihydroxide

Hazard reference values

No reference value for this substance in the sources we hold.

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated by hand rather than machine-read, and none has been written for this substance yet.

Sources for this page

  • ecfr retrieved 2026-09-07
  • gsfa retrieved 2026-09-07

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable:/api/v1/additives/magnesium-hydroxide.json