Aluminum salts in antiperspirants dissolve into the skin’s surface and form a temporary barrier within sweat ducts, which stops the flow of sweat to the skin’s surface. A few studies have evaluated the link between antiperspirant use and breast cancer. Two studies found a increase in breast cancer risk for patients who used antiperspirant products more frequently and longer on shaved underarms were diagnosed with breast cancer at an earlier age. Studies show that aluminum salts in antiperspirants are poorly absorbed by the body, and the little that is absorbed is flushed out by the kidneys. However, if you regularly shave with a razor, aluminum may be more readily absorbed via small nicks and abrasions. To limit potential risks, avoid application of antiperspirants containing aluminum.