SLS vs SLES and other surfactants: what cleans in your shampoo
Sodium lauryl sulfate, sodium laureth sulfate, betaines, glucosides, isethionates – how cleansing ingredients differ and what “sulfate-free” really means.
Updated: 31 October 2026 · Reviewed by: Kamil Pyziak
What surfactants do
Surfactants are the ingredients that let water lift oil and dirt from skin and hair. One end of the molecule likes water, the other likes oil, so they can surround grease and rinse it away. Shampoos, shower gels, face washes and toothpastes all rely on them.
Most products combine a main surfactant with one or two secondary ones. The combination, the concentration and the other ingredients decide how mild or how stripping the product feels.
SLS and SLES are not the same
Sodium Lauryl Sulfate (SLS) is a strong, inexpensive anionic surfactant with plenty of foam. It is known to irritate skin in tests with longer contact, which is why it is used in rinse-off products.
Sodium Laureth Sulfate (SLES) is SLS that has been ethoxylated. That change makes it milder on skin than SLS at similar levels. The names differ by only two letters, so it is worth reading carefully. Ammonium Lauryl Sulfate and Ammonium Laureth Sulfate are close relatives.
Are sulfates harmful?
Neither SLS nor SLES is banned in EU cosmetics. In rinse-off products, contact with the skin is short. People with very dry, sensitive or eczema-prone skin may still find sulfate-based cleansers too drying and prefer milder alternatives.
For ethoxylated ingredients such as SLES, manufacturers control trace impurities that may form during production; the safety assessment of the product takes this into account.
Gentler alternatives
Amphoteric surfactants such as Cocamidopropyl Betaine are often added to soften sulfate systems and boost foam. Sugar-based (non-ionic) surfactants – Coco-Glucoside, Decyl Glucoside, Lauryl Glucoside – are common in gentle and baby washes.
Amino-acid and isethionate surfactants such as Sodium Cocoyl Isethionate, Sodium Lauroyl Sarcosinate, Sodium Cocoyl Glutamate and Sodium Methyl Cocoyl Taurate are popular in “sulfate-free” shampoos and syndet bars.
What “sulfate-free” means
“Sulfate-free” usually means no SLS, SLES or ammonium lauryl/laureth sulfate. It does not mean the product contains no strong surfactants – some sulfonates, such as Sodium C14-16 Olefin Sulfonate, clean very effectively too.
A sulfate-free shampoo can be a good choice for coloured or dry hair, but mildness always depends on the whole formula.
How to read a cleanser’s INCI
After Aqua, the next ingredient is usually the main surfactant. Then come secondary surfactants, thickeners (Sodium Chloride often thickens sulfate systems), conditioners such as Polyquaternium-10 or Guar Hydroxypropyltrimonium Chloride, fragrance and preservatives.
Foam is not a measure of cleansing power: many mild formulas foam less, and some foam boosters do little for cleansing.
What the label does not tell you
The label shows which surfactants are used but not their amounts or the pH of the product, both of which matter for how it feels. If a cleanser leaves your skin tight or itchy, try a different surfactant system; if irritation persists, talk to a pharmacist or a dermatologist.