Messi Biology states that while “Magnesium Hydroxide” might be an unfamiliar name on a crowded cosmetic ingredient list, this seemingly ordinary inorganic compound has long been a key auxiliary ingredient for enhancing product performance. As a safe raw material that complies with the Technical Safety Standard for Cosmetics, its weak alkalinity, low irritancy, and multifunctionality allow it to play an irreplaceable role in skincare, color cosmetics, and other fields.
The core advantages of cosmetic-grade magnesium hydroxide stem from its unique physicochemical properties. As an inorganic weak base, it ionizes only slightly in water, and its decomposition products—magnesium oxide and water—leave no toxic residues, making it friendly to both the human body and the environment. Its powder form possesses excellent adsorbent properties, while its mild alkaline nature makes it a natural pH regulator. These characteristics allow it to adapt to various cosmetic needs. It is worth noting that its typical concentration in cosmetics is ≤1%, and high-purity raw materials must have heavy metal content controlled below 10ppm to ensure safety.
In skincare products, magnesium hydroxide acts as a “regulator” for balanced formulas. In cleansing products, it neutralizes fatty acids and adjusts the pH to between 6.5 and 8.0, ensuring cleaning power while avoiding excessive irritation to the skin barrier. In exfoliating products containing AHAs or salicylic acid, it serves as a buffering agent to stabilize pH levels, reducing irritation reactions such as redness and peeling. Oil-control masks and clay masks utilize its adsorption properties, often paired with ingredients like kaolin to absorb excess surface sebum and improve the appearance of enlarged pores, making it especially suitable for oily skin.
In the field of color cosmetics, magnesium hydroxide is a “secret weapon” for improving skin feel. Adding 3–10 wt% of magnesium hydroxide to loose or pressed powders enhances the smoothness and adhesion of the powder while absorbing sweat and sebum. This prevents the makeup from becoming cakey or patchy and extends wear time. In foundations and concealers, it helps the powder adhere better to the skin by regulating pH and assists in sebum absorption for a natural matte finish. Its white powder characteristics also provide a slight light-scattering effect, adding a natural brightening glow to the skin.
The synergistic effects of magnesium hydroxide are particularly prominent in specialty functional cosmetics. In anti-acne products, it neutralizes the acidity of ingredients like sulfur, reducing irritation while adsorbing inflammatory secretions to help improve acne issues. In physical sunscreens, it regulates the formula’s pH to prevent the agglomeration of UV filters like zinc oxide and titanium dioxide, ensuring an even and stable protective layer. Some antibacterial products utilize its weak alkalinity to inhibit the growth of Cutibacterium acnes, thereby reducing skin inflammatory responses.
When using cosmetics containing magnesium hydroxide, those with sensitive skin should pay close attention. Although its irritancy is low, high-concentration products may disrupt the skin’s natural acidic barrier (healthy skin pH ≈5.5). It is recommended that sensitive skin types choose formulas with low concentrations or no added magnesium hydroxide. Consumers can check the ingredient list for the INCI name “Magnesium Hydroxide” to make informed choices. This ingredient, derived from natural minerals or seawater extraction, has become a “versatile player” in the cosmetics industry due to its mild and safe nature. From balancing pH and controlling oil to stabilizing formulas and providing soothing anti-inflammatory benefits, magnesium hydroxide quietly guards skin health as an indispensable invisible helper in cosmetics.