Aluminum Hydroxide

Aluminum hydroxide is primarily used as an opacifier/anti-caking agent or as a coating/buffering component for pigments and UV filters, typically at low percentages in leave-on products. Clinical experience and patch-test data suggest it is generally well tolerated with low inherent irritancy, but it is not completely inert and can contribute to mild irritation in highly reactive or compromised skin, especially with occlusion or when part of complex formulas. For patient safety in severe sensitivity/eczema populations, it warrants a very gentle (but not zero-risk) score. Safety Notes: In commercial skincare, aluminum hydroxide is most often used at very low levels (~0.05–0.5%) as an opacifier/viscosity aid or pigment/lake/UV-filter coating and dispersion aid in lotions, cleansers, and makeup-adjacent skin products. Higher levels are seen in mineral sunscreen systems and tinted sunscreens where aluminum hydroxide-treated TiO2/ZnO and related coated pigments contribute materially to the formula, and in some clay/mineral-rich masks and body products, reaching the low-to-mid teens on an as-supplied basis. This range reflects leave-on and rinse-off products available OTC; concentrations are typically constrained by texture/whitening, stability, and regulatory labeling rather than a specific global maximum for aluminum hydroxide itself.