Evidence-basedEditor-reviewedCited sourcesUpdated regularly
Surfactants & Emulsifiers

Sodium Laureth Sulfate

Also known as: SLES, Sodium lauryl ether sulfate, Sodium laureth-2 sulfate

SLS's gentler cousin — the ethoxylated cleanser behind most shampoos, milder by design and by decades of data.

  • By IngredientWiki Editorial Team
  • Fact-checked by IngredientWiki Editorial Team
  • Updated 2026-09-26
  • 2 min read

In short

Sodium laureth sulfate (SLES) is the ethoxylated version of sodium lauryl sulfate (SLS) — the same sulfate base with an extra molecular bridge that makes it measurably gentler on skin while retaining excellent foaming and cleansing. It is the primary surfactant in most shampoos, body washes, and liquid cleansers worldwide. Decades of safety reviews (CIR, SCCS) support its use in rinse-off products, with the standard caveats: it can irritate with prolonged contact, and manufacturing must be purified to remove the trace byproduct 1,4-dioxane. The 'SLS vs SLES' distinction is one of the most useful things a label reader can learn.

  • Ethoxylated sodium lauryl sulfate — gentler by design
  • Primary cleanser in most shampoos and body washes
  • Excellent foam; lower irritation than SLS
  • Purification removes 1,4-dioxane trace concern

What is Sodium Laureth Sulfate?

Sodium laureth sulfate is the ingredient that taught the industry the value of one molecular tweak. Take SLS — a strong, somewhat harsh cleanser — and insert an ethoxylate bridge, and you get SLES: nearly the same foam, measurably less irritation, and the surfactant that now lathers most of the world's shampoo. Its safety file is among the most-reviewed in personal care, with the two honest footnotes every label reader should know: irritation is dose- and contact-time-dependent, and purification matters because of a manufacturing byproduct called 1,4-dioxane.

Where it comes from

Natural sources

  • Derived from lauryl alcohol (coconut/palm source) via ethoxylation and sulfation
  • The ethoxylate bridge reduces protein-denaturing — the chemistry of mildness

How it's made

Viscous liquid; used at 5–25% in rinse-off cleansers and shampoos.

What it does in products

  • Primary foaming and cleansing
  • Oil and dirt emulsification
  • Viscosity building with salt
  • Hard-water tolerance

Benefits

Effective cleansing with good foam

strong evidence

Delivers the rich lather consumers expect while removing oils and buildup efficiently — the functional core of shampoo formulation.

Milder than SLS

strong evidence

Comparative irritation studies consistently show SLES is gentler than SLS, which is why it dominates leave-on-adjacent rinse-off products.

Extensively safety-reviewed

strong evidence

CIR and EU SCCS reviews affirm safety in rinse-off products at standard concentrations.

Side effects & safety

Skin dryness or irritation with prolonged contact (uncommon)Concentration- and contact-time-dependent; rinsing thoroughly minimizes.
Eye stinging (uncommon)Expected with most surfactants; avoid eye contact.

Safety considerations

  • Considered safe in rinse-off products.
  • None significant.
  • Not for: None; patch-test if highly sensitive to sulfates

How it's used

In supplements

Not an oral ingredient.

In skincare

5–25% in rinse-off products; leave-on use is rare and low-concentration.

Regulatory status

  • Permitted cosmetic ingredient; regulated through safety standards.
  • INCI name on cosmetic labels: Sodium Laureth Sulfate.
  • CIR-reviewed and found safe as used in rinse-off products.

Popular products containing Sodium Laureth Sulfate

  • Pantene / Herbal Essences shampoos — SLES-anchored cleansing systemsVarious · Skincare
  • Dove Body Wash — SLES with conditioning co-surfactantsDove · Skincare
  • Neutrogena Body Clear Body Wash — SLES-based acne body washNeutrogena · OTC drug

Product names and brands are shown for reference and belong to their respective owners.

SLES vs SLS

The ethoxylate bridge spaces the sulfate head from the fatty tail, reducing the molecule's ability to disrupt skin proteins — hence SLES's lower irritation in comparative testing. The trade is minor: SLES requires purification to strip 1,4-dioxane, a byproduct of ethoxylation that reputable manufacturers remove to trace levels.

The 1,4-dioxane question

1,4-dioxane is a probable human carcinogen formed during ethoxylation. It is not an ingredient but a process byproduct, and vacuum stripping removes it from finished SLES to undetectable or trace levels. Major-brand testing and certification programs address this; the concern attaches to unregulated supply chains, not the ingredient itself.

Frequently asked questions

Should I avoid sulfates in shampoo?

Only if your scalp is genuinely irritated or you have color-treated hair you want to protect. For most people, SLES-based cleansers are safe and effective — the avoidance is preference, not necessity.

Is SLES carcinogenic?

No — SLES itself is not. The confusion traces to 1,4-dioxane, a byproduct removed in properly manufactured material.

Why do sulfate-free shampoos lather less?

Alternative surfactants (glucosides, isethionates, amino-acid based) are gentler but foam less richly. That trade-off is the whole reason sulfates remain the industry default.

The bottom line

Sodium laureth sulfate is a well-reviewed, effective, and comparatively gentle cleanser — the sulfate to understand before deciding whether to avoid sulfates at all.

References

  1. Sodium laureth sulfate — Cosmetic Ingredient Review. CIR. https://www.cir-safety.org/ingredients
  2. Surfactant irritation: SLS vs SLES comparison. PubMed Central. https://pubmed.ncbi.nlm.nih.gov/28257056/
  3. 1,4-Dioxane in cosmetics — FDA. U.S. Food and Drug Administration. https://www.fda.gov/cosmetics/cosmetic-ingredients/14-dioxane-cosmetics