Soluble Proteoglycan

Soluble proteoglycans are high–molecular weight skin-conditioning/humectant biopolymers typically used at low percentages in leave-on products, and they are generally well tolerated with low rates of irritation in routine cosmetic use. However, as a protein/glycosaminoglycan complex (often marine- or animal-derived), there is a small but real risk of sensitization in highly reactive or eczema-prone patients, so it cannot be considered completely inert. Given typical concentrations and the need to err on patient safety, it best fits a very gentle (0.2) profile rather than exceptionally gentle or inert. Safety Notes: In commercial leave-on products (serums, ampoules, creams), soluble proteoglycan is most often used as a low-level “bioactive” in the 0.001–0.1% range, consistent with supplier active solutions where the INCI appears near the end of the list. High-strength consumer-available products (especially Japanese “proteoglycan” essences/ampoules and concentrated booster serums) can reach roughly 1–3% active, with higher levels being uncommon due to raw material cost, viscosity/film-forming effects, and stability/odor constraints. Use in rinse-off products is typically lower (often ≤0.05%) because contact time is short and deposition is limited.