# Sodium Laureth Sulfate (SLES)

Canonical URL: https://guide.rozhair.com/glossary/sles/

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SLES is SLS with an extra chemistry step — ethoxylation — that attaches ethylene oxide molecules to the surfactant to soften its action on the skin. That step reduces irritation and makes SLES a better choice than SLS, which is why the vast majority of "regular" shampoos on shelves today are SLES-based rather than SLS-based.

But SLES is still a sulfate. It still strips oil, still opens the cuticle, and still fades color faster than non-sulfate surfactants. The ethoxylation process also carries a historical contamination concern: 1,4-dioxane, a byproduct of the reaction, must be stripped before SLES reaches market (FDA-monitored but not strictly regulated in the US).

"Sulfate-free" on a label means no SLS *or* SLES — if a brand removes one but keeps the other, it's not sulfate-free.