Aluminum hydroxide is a mineral found in nature. It's a very stable form of aluminium closely related to Alumina, not to be confused with aluminium salts (like Aluminum chloride, Aluminum nitrate, Aluminum sulphate) often used in deodorants. Aluminum hydroxide is often used to treat heartburn by neutralizing stomach acids. Toothpastes also often contain Aluminum hydroxide, where it is used as an abrasive and neutralises the effect of acids in the mouth, which can help to reduce the amount of germs. In makeup it is mostly used in primers, foundations, and lipsticks and in skincare it is often found in moisturizers (where it is used as an emollient, opacifying agent (making a product less transparent), and skin protectant. It can frequently be found in sunscreens, where it is used to coat titanium dioxide, making it much more stable while at the same time increasing the SPF. It also prevents it from clumping so it spreads easier. Aluminum hydroxide is generally regarded as very safe and may be used in certified natural cosmetics.