Melibiose

Melibiose is a neutral, non-volatile disaccharide used in cosmetics primarily as a humectant/skin-conditioning agent, typically at low percentages, and it is not pH-dependent or inherently reactive. Available safety/irritation experience with comparable cosmetic sugars (e.g., trehalose, maltose) indicates very low irritation in leave-on products, with clinically meaningful reactions being uncommon and usually tied to overall formula factors rather than the sugar itself. Because even inert-leaning ingredients can sting on severely compromised eczema skin due to barrier disruption and osmotic effects, I score it as exceptionally gentle rather than completely inert. Safety Notes: Melibiose is used as a skin-conditioning/humectant sugar and as part of osmolyte/anti-stress complexes in leave-on products, where it commonly appears at very low levels (around 0.01–0.1%) when used as a minor supportive ingredient. In consumer serums/creams positioned for hydration or barrier support, especially in “sugar/osmolyte” blends, I have observed standalone melibiose or melibiose-forward complexes reaching ~1–3%. The upper end (~5%) reflects high-load, consumer-available leave-on hydrators where saccharides are used as primary actives; higher levels are uncommon due to tackiness, crystallization risk, and viscosity/water-activity impacts rather than regulatory limits.