What it is
Aluminum chlorohydrate is a water-soluble aluminum salt best known as the active in many antiperspirants, where it helps reduce surface wetness. In other formulas it acts as an astringent and can contribute to a mattifying or sebum-managing feel. In cooling or spray-type sunscreens it may be included for its astringent, finish-modifying properties rather than for UV protection.
Safety & warnings
Aluminum chlorohydrate is widely used in personal care. It can be mildly astringent and, in some individuals, may cause skin irritation, particularly on freshly shaved or broken skin. It is not a recognized fragrance allergen and is not an oil, so comedogenicity is not a typical concern.
Origin & sourcing
Synthetic inorganic aluminum salt manufactured from aluminum sources.
History
Aluminum salts have been used as antiperspirant actives for many decades.
Questions everyone asks
Why is an antiperspirant ingredient in a sunscreen?
It is used for its astringent, finish-modifying effect that can help the product feel drier or more matte; it does not provide UV protection.
Can it irritate skin?
Some people find aluminum salts mildly irritating, especially on shaved or compromised skin; a patch test can help if you are sensitive.