Quaternium-51 ●
TL;DR. This ingredient is a skin-conditioning film-former that helps bind water at the skin or hair surface and leaves a thin, smooth-feeling layer. It is mainly used for moisturization, barrier-feel support, and reduction of tack or roughness in leave-on formulas.
What does Quaternium-51 do in a cosmetic formula?
This ingredient is a skin-conditioning film-former that helps bind water at the skin or hair surface and leaves a thin, smooth-feeling layer. It is mainly used for moisturization, barrier-feel support, and reduction of tack or roughness in leave-on formulas.
Is Quaternium-51 clean?
From a clean-beauty perspective, it is usually well tolerated at cosmetic use levels, but it has friction because it is a synthetic quaternary polymer. The main scrutiny is not common allergen status, but petrochemical origin, polymer persistence, and limited natural-standard compatibility.
Is Quaternium-51 sustainable?
This material is synthetic and typically made from petrochemical-derived monomers. It is not expected to be readily biodegradable, so its end-of-life profile is weaker than readily biodegradable humectants, gums, or plant-derived conditioning agents.
Is Quaternium-51 COSMOS-approved?
It is not permitted in COSMOS-natural or COSMOS-organic as a routine cosmetic ingredient because it is a synthetic quaternary polymer. Its Green Chemistry fit is limited, with low-dose performance as a benefit, but nonrenewable feedstocks and low expected biodegradability as drawbacks.
How does Quaternium-51 work chemically?
The molecule is a zwitterionic methacrylate-based copolymer with phosphate and quaternary ammonium side groups, designed to hold water while forming a soft, substantive surface film. It is typically used at low levels in leave-on products, often around 0.01% to 1% active, and is generally stable across normal cosmetic pH ranges when compatible with the formula’s electrolyte and surfactant system.
Last updated 2026-05-14