Glucosamine

Glucosamine is a skin-identical, hydration-restoring modified glucose (type of sugar) with one hydroxyl (OH) group substituted with an amine, making it an aminomonosaccharide. It offers a multitude of benefits for skin, including moisture retention and refining rough texture, which helps promote a more even skin tone.

It has an excellent safety profile, as last assessed by the Cosmetic Ingredient Review (CIR) Expert Panel in 2022.

For cosmetics, derivatives of glucosamine tend to be used more often than the original form due to greater stability, bioavailability, and ease of formulation. Examples include plant-derived glucosamine HCI (the hydrochloride form) or acetyl glucosamine, which pairs well with niacinamide for further improvement in the appearance of dark spots and uneven tone. Use levels of glucosamine and derivatives in cosmetics ranges from 0.5–5%.

Getting a bit more science-y, despite glucosamine’s smaller molecular size, it has poor transdermal absorption because of its polarity and hydrosolubility. As such, formulation techniques to improve delivery are essential for skin permeation of this amino acid sugar.