Sodium Laureth Sulfate

Sodium laureth sulfate, often shortened to SLES, is a surfactant: it lets water lift away oil and dirt and it makes lather. It is a cleanser in many shampoos, body washes and liquid soaps. Despite the similar name it is a different ingredient from sodium lauryl sulfate (SLS), and in patch tests it irritated skin far less.

In the Sulfates group

Checked against 3 sources on 10 October 2026. How pages are written

What it does

The EU's CosIng database lists two functions for it: a cleansing surfactant, which helps water wash away oil and dirt, and an emulsifying surfactant, which helps oil and water mix.¹ In a shampoo it is usually the main cleanser, near the top of the list after water.

SLES is not SLS

The "eth" in laureth marks a change to the molecule: SLES belongs to the salts of sulfated ethoxylated alcohols, a different family from the plain alkyl sulfates such as SLS.²

The difference shows on skin. In a patch-test study comparing the two at the same concentrations, SLS produced a pronounced irritant reaction and SLES a far milder one.³ A patch held on skin for up to a day is not the same as a shampoo rinsed off after a minute, but it shows the two names are not interchangeable.

The finished formula matters

The US Cosmetic Ingredient Review found that SLES can irritate skin and eyes but is not a sensitiser, and that in practice it is not regularly seen to be irritating because of the formulations it is used in. The panel's conclusion was that it should be used only when it can be formulated to be non-irritating.²

Shampoos often combine it with other surfactants, such as Cocamidopropyl Betaine. How a shampoo feels depends on that whole system, not on one name.

How it appears on a label

As Sodium Laureth Sulfate, sometimes as Sodium Lauryl Ether Sulfate. Ammonium laureth sulfate is a close relative with its own name.² A "sulfate-free" claim means the formula uses other cleansers; it does not say which, or how gentle they are.

What it does in a formula

Cleanses and foamsOfficial EU function: Surfactant - cleansing

Helps oil and water mixOfficial EU function: Surfactant - emulsifying

Why some people watch for it

Sulfates

Some people avoid sulfate cleansers because they find them stripping on dry skin, curly hair or colour-treated hair.

A group is a fact about the ingredient, not a judgement of it.

Sources

European Commission. CosIng entry SODIUM LAURETH SULFATE: INCI name and functions, as exported on 9 October 2026. ec.europa.eu Checked 10 October 2026.
Robinson VC, et al. Final report of the amended safety assessment of sodium laureth sulfate and related salts of sulfated ethoxylated alcohols. International Journal of Toxicology 2010;29(4 Suppl):151S-61S. pubmed.ncbi.nlm.nih.gov Checked 10 October 2026.
Löffler H, Happle R. Profile of irritant patch testing with detergents: sodium lauryl sulfate, sodium laureth sulfate and alkyl polyglucoside. Contact Dermatitis 2003;48(1):26-32. pubmed.ncbi.nlm.nih.gov Checked 10 October 2026.

Written for this site from the sources above and checked against them on 10 October 2026. Not reviewed by a dermatologist or toxicologist, and not medical advice. Spotted something wrong? Tell us.