What it is
Distearyldimonium chloride is a dialkyl quaternary ammonium salt (quat) that carries a positive charge, allowing it to deposit on and condition surfaces. In hair products it reduces static and improves combing and softness, and in skin products and sunscreens it can act as a cationic emulsifier or emulsion stabilizer. Its long stearyl chains also contribute to the texture and body of creams.
Safety & warnings
Generally well tolerated in rinse-off and leave-on cosmetics at typical use levels. As a cationic surfactant it can be mildly irritating at higher concentrations, so it is used at low levels in leave-on products. It is not a recognized fragrance allergen.
Origin & sourcing
Synthetic; manufactured from long-chain (stearyl) fatty alcohols converted to a dimethyl quaternary ammonium chloride salt.
Questions everyone asks
What is a quaternary ammonium compound?
It is a positively charged molecule, often called a quat, that binds to surfaces like hair and skin to condition them and reduce static.
Why is it in a sunscreen?
It can serve as a cationic emulsifier or emulsion stabilizer and contribute to the cream's texture and conditioning feel.