What it is
This is the sodium salt of sulfated cetearyl alcohol, combining cetyl and stearyl fatty alcohol chains. In a sunscreen it acts mainly as an emulsifier, helping blend the oil and water phases into a stable, uniform emulsion, and it can contribute mild cleansing or wetting properties. It is often paired with co-emulsifiers to build the desired texture.
Safety & warnings
As an anionic surfactant it has the potential to be mildly irritating to skin or eyes at higher concentrations, but in leave-on products it is typically used at low levels as an emulsifier and is generally well tolerated. It is not a known fragrance allergen.
Origin & sourcing
Synthetic, made by sulfating cetearyl alcohol (a blend of cetyl and stearyl alcohols, which may be plant- or petroleum-derived) and neutralizing with sodium.
Questions everyone asks
What does sodium cetearyl sulfate do?
It is primarily an emulsifier, helping the oil and water in a formula combine into a stable, uniform cream or lotion.
Is it a harsh ingredient?
It is an anionic surfactant that can be mildly irritating at high levels, but in sunscreens it is used at low emulsifying concentrations and is generally well tolerated.