The metal commonly used in antiperspirants to reduce sweating is aluminum. Antiperspirants usually contain aluminum salts such as aluminum chloride, aluminum chlorohydrate, or aluminum-zirconium compounds rather than pure metallic aluminum.
These salts react with electrolytes and keratin in sweat ducts, forming temporary gel-like plugs that reduce the amount of sweat reaching the skin’s surface. Their mild astringent action may also make the ducts contract slightly. The plugs are gradually removed as the outer skin naturally sheds.
A common mix-up is confusing antiperspirant with deodorant. Deodorant primarily masks odor or limits odor-producing bacteria, while antiperspirant targets perspiration itself. Sweat is largely odorless until bacteria break down organic components, especially in areas containing apocrine glands.
Commercial antiperspirants have a long history: Everdry appeared in 1903, and Jules Montenier patented a modern, less-irritating formulation in 1941. Aluminum concerns are widely discussed, but the stored answer remains the standard quiz answer.