Messi Biology reports that while “Magnesium Hydroxide” may be an unfamiliar name on the lengthy list of cosmetic ingredients, this seemingly simple inorganic compound has long been a crucial auxiliary component for enhancing product performance. As a safe raw material compliant with the Safety and Technical Standards for Cosmetics, its combination of weak alkalinity, low irritancy, and versatility makes it indispensable across skincare, color cosmetics, and other applications.
The core advantage of cosmetic-grade Magnesium Hydroxide is rooted in its unique physicochemical properties. As an inorganic weak base, it only weakly ionizes in water, decomposing into Magnesium Oxide and water with no toxic residue, making it environmentally and human-friendly. Its powdered form offers excellent adsorption capabilities, while its mild alkalinity makes it a natural pH regulator. These features enable it to suit diverse cosmetic requirements. Notably, its typical usage level in cosmetics is ≤1%, and high-purity raw materials must have heavy metal content controlled below 10ppm to ensure consumer safety.
Role in Skincare Products: The Formula Regulator
In skincare products, Magnesium Hydroxide functions as a formula “regulator.”
- Cleansing Products: In facial cleansers, it neutralizes fatty acids to adjust the pH level to 6.5–8.0, maintaining cleansing power while preventing excessive irritation to the skin barrier.
- Exfoliating Treatments: For exfoliating products containing Alpha Hydroxy Acids (AHAs) or Salicylic Acid, it acts as a buffer to stabilize the pH, minimizing irritating side effects such as redness and peeling.
- Oil Control: Oil-control and clay masks leverage its adsorptive qualities, where it works with ingredients like Kaolin to soak up excess sebum from the skin surface, addressing large pore concerns, making it particularly beneficial for oily skin.
Role in Color Cosmetics: The Secret Weapon for Skin Feel
In the color cosmetics sector, Magnesium Hydroxide serves as the “secret ingredient” for enhancing skin feel and makeup longevity.
- Setting Powders: When incorporated at 3–10 wt% into loose and setting powders, it not only boosts the powder’s slip and adherence but also absorbs sweat and oil, preventing makeup caking or patchiness and prolonging wear.
- Foundations/Concealers: In foundations and concealers, it adjusts the pH to promote better powder-to-skin adhesion and assists in absorbing sebum, resulting in a more natural, matte finish.
- Brightening: Its inherent white powdered nature also lends a slight light-scattering effect, contributing to a natural skin brightening appearance.
Role in Specialized Functional Cosmetics: Synergistic Benefits
The synergistic benefits of Magnesium Hydroxide are particularly prominent in specialized functional cosmetics.
- Acne Treatments: It neutralizes the acidity of ingredients such as sulfur, mitigating irritation while absorbing inflammatory exudates to help resolve blemishes.
- Physical Sunscreens: It regulates the formula’s pH, preventing the agglomeration of UV filters like Zinc Oxide and Titanium Dioxide, which ensures stable and uniform sun protection efficacy.
- Antibacterial Action: Furthermore, some antibacterial products utilize its mild alkalinity to inhibit the growth of Cutibacterium acnes (formerly Propionibacterium acnes), thus helping to reduce skin inflammation.
When using cosmetics containing Magnesium Hydroxide, individuals with sensitive skin should exercise caution. Although its irritancy is low, high-concentration products could potentially disrupt the skin’s natural acid mantle (healthy skin pH≈5.5). Sensitive skin types are therefore advised to opt for formulations with low concentrations or none at all. Consumers can make informed decisions by checking the ingredient list for the INCI name “Magnesium Hydroxide.” This ingredient, sourced from natural minerals or seawater, has become a “versatile player” in the cosmetics industry due to its gentle and safe profile. From pH balancing and oil absorption to formula stabilization and soothing anti-inflammatory effects, Magnesium Hydroxide quietly contributes to skin health, making it an indispensable, invisible aid in modern cosmetics.