Amino acids are used in cosmetic formulations to increase water retention and skin moisture. Since amino acids are smaller in size, they may reach deeper into the stratum corneum's cell layers than proteins with a higher molecular weight, such as collagen. The amino acid composition of the protein used influences how the ingredient feels on the skin. Despite the fact that amino acids are important skin components, the skin does not use topically applied amino acids to form new skin because amino acid function in skin formation is a highly complex process.

To combat the signs of ageing, amino acids can be blended with other ingredients that have skin-restorative properties.