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Magnesium Hydroxide
AKA “Milk of magnesia, Magnesium dihydroxide, Magnesium hydrate, Magnesium hydroxide (Mg(OH)2), Magnesium(II) hydroxide, Phillips magnesia tablets, Magnesium (as hydroxide), Magnesii hydroxidum”
Synthetic
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Ingredient Facts
Magnesium hydroxide
AKA: Milk of magnesia, Magnesium dihydroxide, Magnesium hydrate, Magnesium hydroxide (Mg(OH)2), Magnesium(II) hydroxide, Phillips magnesia tablets, Magnesium (as hydroxide), Magnesii hydroxidum
Synthetic · Absorbent | Buffering · EWG: 4
Plant-Derived
Synthetic
Clean
Helps absorb excess oil and moisture while balancing pH to keep skin feeling fresh and comfortable.
Solubility Practically insoluble in water and in ethanol
Formula
H2MgO2
Mol. Weight
58.32
CAS #
1309-42-8
Form
Powder
Plant-Derived
Synthetic. Produced from magnesium salts or magnesium oxide through reaction with water or calcium hydroxide. Synthesized via precipitation, calcination, or hydration of magnesium compounds in industrial processes.
Function
Absorbent | Buffering
Benefits
Absorbent
Buffering
Anti-Inflammatory
Boosts Collagen
Wound Healing
Absorbs excess oil
Maintains optimal pH
Traditional Use
Developed as a modern cosmetic and pharmaceutical ingredient in the 19th-20th centuries. Used industrially as a base and buffering agent; adopted in cosmetics for pH adjustment and as a mild abrasive in some formulations.
Skin Types
all-skin-types
Best For
Target
General
Melanin-Rich Skin
Suitable
Pregnancy Safe
Yes
EWG Score4
CIR Safety Findings
medical-approval, all-shades-safe, Not a Sensitizer
Regulatory Status
USA✔ permitted
EU⚠ restricted
JAPAN⚠ restricted
CANADA⚠ restricted
Verified Feb 2026
Data: PubChem · CosIng · EWG · CIR