What Is Aluminum Hydroxide?
Aluminum hydroxide is a white, powdery substance made when aluminum salts react with water to form a solid gel that is then dried and milled. Chemically, it is composed of aluminum atoms bonded to hydroxide groups, giving it the formula Al(OH)3. The mineral form, called gibbsite, occurs in nature, but the ingredient used in cosmetics is almost always produced in controlled factory settings to ensure purity.
The beauty industry first looked at aluminum hydroxide decades ago as a gentle way to give creams a smooth feel and add opacity to makeup. Over time, formulators discovered that it can also help keep moisture in the skin, thicken products and create a soft protective film on the surface. Today it is made by dissolving refined aluminum in water, adjusting the pH so the hydroxide forms, then filtering and drying the solid. This straightforward process results in a fine, non-gritty powder that blends well into lotions, creams and color cosmetics.
You will most often see aluminum hydroxide in mineral sunscreens, foundations, tinted moisturizers, face masks, soothing creams for sensitive skin and anti-aging serums that aim for a silky finish. It is valued because it works well with other ingredients, stays stable over time and does not add any noticeable scent or color of its own.
Aluminum Hydroxide’s Cosmetic Benefits/Uses
Formulators choose aluminum hydroxide for several practical reasons that improve both product performance and the feel on skin.
- Humectant: Helps draw a small amount of water from the air into the product and the upper layers of skin, supporting light hydration
- Opacifying: Adds a gentle cloudiness that can blur minor skin imperfections, making foundations and primers look more even
- Emollient: Contributes to a smooth glide and soft after-feel, which leaves skin feeling conditioned rather than dry or tight
- Skin Protecting: Forms a thin breathable barrier that shields the surface from everyday irritation such as wind or pollution particles
- Viscosity Controlling: Thickens watery formulas so they stay put on the skin and gives creams a stable, uniform texture that resists separating
Who Can Use Aluminum Hydroxide
Because aluminum hydroxide is inert and gentle it works for almost every skin type including dry, normal, combination, oily and sensitive. Its film-forming ability can help calm reactive skin yet it is light enough that it will not feel greasy on oilier complexions. The main group that should steer clear is anyone with a known allergy to aluminum compounds as even small traces can provoke redness or itching.
The ingredient is mined from mineral sources and processed without any animal by-products so it is suitable for both vegans and vegetarians.
Pregnant and breastfeeding women are not generally restricted from using skincare containing aluminum hydroxide because topical absorption is minimal. This statement is not medical advice and anyone who is expecting or nursing should confirm product choices with a healthcare professional to be safe.
Aluminum hydroxide does not cause photosensitivity and it can actually improve the wear of mineral sunscreens making it a good daytime option. There are no known interactions with common active ingredients like retinoids or vitamin C so it fits easily into most routines.
Potential Side Effects/Adverse Reactions
Responses to any cosmetic ingredient differ from person to person. The effects listed below are possible yet uncommon when aluminum hydroxide is applied to skin in a properly formulated product.
- Mild redness or stinging in highly sensitive skin
- Allergic contact dermatitis in individuals who have an existing aluminum allergy
- Temporary tight or dry feeling if used in a very high concentration without additional moisturizers
- Clogged pores for those already prone to heavy occlusive buildup when aluminum hydroxide is paired with rich oils and waxes
If any of these reactions occur stop using the product and consult a qualified medical professional for guidance.
Comedogenic Rating
Rating: 1 / 5
Aluminum hydroxide is an inert mineral powder that sits on top of the skin without melting into pores or delivering oils that can trap debris. Its particle size is large enough that it does not easily lodge inside follicles, and it is typically used at low levels to adjust texture rather than as a heavy filler. For these reasons it earns a very low comedogenic score of 1.
Most people prone to acne or breakouts can use products containing aluminum hydroxide without extra concern. If the formula also contains rich butters or waxes the overall product could still be pore clogging, but this would be due to those other ingredients, not the aluminum hydroxide itself.
Summary
Aluminum hydroxide acts as a gentle humectant that draws a bit of moisture to the skin, an opacifier that blurs imperfections, an emollient that leaves a soft feel, a protector that forms a light barrier and a viscosity controller that keeps lotions stable. It performs these roles thanks to its fine particle size and ability to bind a thin water layer while suspending uniformly in creams and gels.
The ingredient is fairly common in mineral sunscreens and makeup bases yet it is not as talked about as trendier actives because it works quietly behind the scenes to improve texture and wear.
Overall safety is high; it is non irritating for most skin types, rarely allergenic and non photosensitizing. As with any new skincare ingredient it is wise to do a small patch test before full use to rule out individual sensitivities.