Magnesium Carboxymethyl Beta-Glucan

Magnesium carboxymethyl beta-glucan is a modified beta-glucan used as a soothing, barrier-supporting humectant/film former, typically at low concentrations (about 0.1–1%) in leave-on products. Beta-glucans and their derivatives are generally well tolerated in patch testing with low irritancy and are often included in formulas intended for compromised or sensitized skin. While true irritation is uncommon, any polymeric/metal-salt derivative can rarely provoke stinging on severely impaired barriers, so it is best classified as very gentle rather than completely inert. Safety Notes: In commercial skincare, magnesium carboxymethyl beta-glucan is most often used as a soothing/skin-repair polymer at low active levels (~0.01–0.1%) in mass-market leave-on creams/serums and in some rinse-off cleansers where deposition is limited. Higher-strength consumer-available “barrier repair” and post-procedure calming serums/ampoules and masks commonly run ~0.5–1.0%, with the highest OTC formulations observed around ~2% where viscosity/film-forming and cost become practical constraints. This ingredient is primarily found in leave-on products; rinse-off usage tends to stay toward the lower end due to performance and cost-in-use.