Alpha-Glucan

Alpha-glucan is a glucose-derived polysaccharide used as a prebiotic/humectant and skin-conditioning agent, typically included around 0.1–5% in leave-on products. Available safety assessments and human use experience indicate a very low rate of irritation or sensitization, with reactions being uncommon and usually tied to overall formula factors rather than the polymer itself. For severely reactive or eczematous skin I still avoid calling it “exceptionally gentle” because any bioactive/prebiotic support ingredient can be a minor trigger in a small subset, but clinically it remains very gentle at typical concentrations. Safety Notes: In commercial skincare, alpha-glucan is most often used as a prebiotic/humectant support active: at the low end (~0.05–0.2%) it appears as a minor microbiome-support claim ingredient in serums, toners, and cleansers (often within blends). Typical leave-on products sit around ~0.5–2%, while the highest consumer-available “microbiome/prebiotic concentrate” leave-on formulations reach ~3–5% as a primary functional active; rinse-off products generally use the lower end due to short contact time and cost. There is no specific EU/FDA cosmetic concentration limit for alpha-glucan, so observed maxima are driven by sensorial/stability and raw material practicality rather than regulation.