Cysteine ●
TL;DR. This ingredient is used mainly as a reducing agent in hair waving, straightening, and bond-modifying systems, where it helps alter disulfide bonds in hair. It can also serve as a hair and skin conditioning additive in lower-level use.
What does Cysteine do in a cosmetic formula?
This ingredient is used mainly as a reducing agent in hair waving, straightening, and bond-modifying systems, where it helps alter disulfide bonds in hair. It can also serve as a hair and skin conditioning additive in lower-level use.
Is Cysteine clean?
This ingredient is generally well accepted in clean-beauty frameworks because it is a naturally occurring amino acid with a low sensitization profile at typical cosmetic levels. In alkaline reducing systems, comfort depends more on formula strength, pH, and exposure time than on the molecule alone.
Is Cysteine sustainable?
This material can be made by fermentation or by hydrolysis of protein-rich feedstocks, so sourcing details matter. It is water soluble, readily biodegradable, and not associated with environmental persistence or bioaccumulation concerns.
Is Cysteine COSMOS-approved?
It is generally compatible with COSMOS-natural and COSMOS-organic standards when produced from permitted natural or fermentation-derived feedstocks using allowed processing. From a Green Chemistry perspective, it aligns well when made by fermentation, with good biodegradability and no need for persistent solvents in the finished ingredient.
How does Cysteine work chemically?
The molecule is a sulfur-containing amino acid with a reactive thiol group, which is why it can participate in redox chemistry with hair keratin disulfide bonds. It oxidizes readily to a disulfide dimer in the presence of air, metals, or higher pH, so formulas often manage pH, oxygen exposure, and chelation for stability.
Last updated 2026-05-13