Magnesium oxide (MgO) is an inorganic compound that, as a fine, white powder, is widely used in cosmetic formulations. In creams, powders, or lotions, it serves as a white colorant (CI 77711), lending coverage or optical brightness to the formulation. It also helps absorb excess sebum, thus providing a matte complexion. At the same time, its buffering effect can stabilize the pH of the product and contribute to the desired opacity and consistency. Due to its properties, magnesium oxide is a common excipient in color cosmetics and sunscreen products. (1)

1 Bährle-Rapp, M. (2012). Springer Lexikon Kosmetik und Körperpflege. 4th revised and expanded edition. Springer.