Sodium Laureth Sulfate (SLES)
SLES is the most commonly used foaming surfactant in shampoos, shower gels, liquid soaps and washing-up liquids. It is milder on the skin than its relative SLS and is considered safe in rinse-off products. The main topic of debate is the trace residue of 1,4-dioxane that can remain from manufacturing; reputable manufacturers minimise this residue through purification.
Risk range
1 is the lowest and 10 the highest risk. The range depends on the amount used, whether the product is rinsed off and how it is used. The Temiz İçerik app uses the same ranges.
In rinse-off products it usually stays at the lower end of the range, with low irritation potential; it moves towards the upper end on very sensitive or eczema-prone skin and at high concentrations.
In washing-up liquids and surface cleaners, contact is brief and diluted; prolonged work with wet hands can cause dryness, which gloves prevent.
What is SLES and what does it do?
Sodium laureth sulfate is an anionic surfactant made by taking lauryl alcohol, obtained from coconut or palm kernel oil, first through ethoxylation (reacting it with ethylene oxide) and then through sulfation. The “eth” in its name refers to this ethoxylation step.
Its job is the same as that of SLS: to make dirt and grease soluble in water and to create a rich, creamy lather. Because ethoxylation makes the molecule larger, SLES penetrates the skin less and has a markedly lower irritation potential. That is why SLES is now preferred over SLS in most shampoos and shower gels.
Which products contain it?
- Shampoos, shower gels, liquid hand soaps and bubble baths
- Most hair and body cleansers apart from baby shampoos
- Washing-up liquids, surface and glass cleaners
- Some liquid laundry detergents
On the label it usually comes right after Aqua and is often used with cocamidopropyl betaine, a milder co-surfactant; this pairing both boosts the lather and reduces irritation.
Is it harmful? The scientific assessment
The independent Cosmetic Ingredient Review (CIR) panel has found alkyl ether sulfates safe in cosmetics when formulated to be non-irritating. The pure substance irritates the eyes and skin at high concentrations; however, in products it is present in diluted form and is rinsed off quickly.
Claims that SLES causes cancer are not based on the substance itself but on the 1,4-dioxane residue that can form as a by-product during ethoxylation. 1,4-dioxane is classified by the IARC in Group 2B (possibly carcinogenic to humans; limited evidence). In the EU it is banned from being deliberately added to cosmetics; technically unavoidable trace residues are kept under control through the manufacturer's safety assessment and minimised using methods such as vacuum stripping.
In short, no serious health concern is expected from SLES in a properly manufactured, rinse-off product. Some people may experience dryness and mild irritation; this is mostly related to frequent washing and sensitive skin.
Who should be careful?
- People with atopic dermatitis or very dry skin: Although milder, SLES also removes skin oils; dryness can increase with long showers and frequent washing.
- People with coloured, curly or easily broken hair: Strong cleansing can make hair feel dry; sulfate-free products may be more comfortable.
- Eye contact: It stings if it gets into the eyes; rinsing with plenty of water is enough.
What to do when you see it on a label
If your skin has no problems, there is no need to give up a shampoo or shower gel containing SLES. If you experience dryness or itching, you can try products whose formulas contain milder surfactants such as betaine or coco glucoside, or fully sulfate-free products. Wearing gloves while cleaning greatly reduces the drying effect on the hands of all detergents, including SLES.
Frequently asked questions
Which is more harmful, SLES or SLS?
In terms of irritation, SLS is stronger; thanks to ethoxylation, SLES is milder on the skin. The issue specific to SLES is trace 1,4-dioxane residue, which is minimised through purification during manufacturing.
Does SLES cause cancer?
SLES itself is not classified as a carcinogen. The debate concerns trace residues of 1,4-dioxane; in properly manufactured products these levels are very low.
Does SLES cause hair loss?
There is no scientific evidence to support this. Strong cleansers can make hair feel dry and brittle, but they have not been shown to cause hair loss by affecting the hair roots.
Sources
Updated: 2026-10-11 · How we score
This page is for general information and is not personal medical advice. Warnings on the product label and the advice of a health professional always come first.