Fructooligosaccharides

Fructooligosaccharides are prebiotic sugars used mainly as humectants/skin-conditioning agents, typically at low percentages, and they are not pH-dependent actives. Available cosmetic and patch-test experience suggests low irritation and low sensitization risk, though any carbohydrate-based humectant can occasionally sting on severely compromised or fissured eczema skin due to barrier disruption. Given my high-risk patient population, I rate it as very gentle but not completely inert. Safety Notes: In commercial skincare, fructooligosaccharides (often positioned as a prebiotic/humectant) are frequently used at very low levels (~0.05–0.5%) in leave-on serums/creams and even lower-end inclusion levels in rinse-off cleansers where short contact time limits need. Higher-strength consumer products marketed as “prebiotic” moisturizers/soothing masks and some microbiome-focused formulations commonly place FOS in the ~1–5% range, with a small number of OTC products using up to ~10% when the formula is built around a carbohydrate prebiotic system (higher levels are limited by tackiness, water activity/microbial preservation burden, and sensorial constraints rather than specific regulatory caps).