Also on labels as: Sodium Lauryl Ether Sulfate, SLES, Sodium Polyoxyethylene Lauryl Ether Sulfate, Sodium C12-14 Pareth Sulfate
In one line
A widely used cleansing surfactant that lifts oils and dirt from skin and hair while producing rich lather.
What is Sodium Laureth Sulfate (SLES)?
Sodium Laureth Sulfate is a synthetic surfactant made by ethoxylating lauryl alcohol, typically derived from coconut or palm oil, then treating it with sulfuric acid and sodium hydroxide. The ethoxylation step is what distinguishes it from its close relative Sodium Lauryl Sulfate, making it gentler on skin. It is one of the most common cleansing agents in rinse-off personal care products worldwide.
What does it do in the product?
SLES reduces surface tension between water and oily residues, allowing them to be rinsed away together. It also generates the dense, stable foam that consumers associate with effective cleansing in shampoos and body washes. Its ability to work in both hard and soft water makes it a practical choice for mass-market formulations.
Where you usually find it
Shampoos and conditioners
Body washes and shower gels
Liquid hand soaps
Dishwashing liquids
Bubble bath products
Toothpastes
Is Sodium Laureth Sulfate (SLES) something to worry about?
At the concentrations used in rinse-off products, SLES is generally regarded as safe by major regulatory bodies. However, the ethoxylation process can introduce trace levels of 1,4-dioxane, a potential contaminant that has drawn regulatory attention; manufacturers can remove it through vacuum stripping, and the FDA monitors residual levels in cosmetics. People with compromised skin barriers, eczema, or existing scalp sensitivity sometimes report irritation, particularly with repeated exposure or use in leave-on contexts.
Who should pay attention
People with eczema or sensitive skin, as it can disrupt a weakened skin barrier
Those with a coconut or palm oil allergy, since the source material may be relevant
Individuals managing scalp conditions such as seborrheic dermatitis
Parents choosing products for infants or young children with delicate skin
Anyone following a palm-oil-free lifestyle for environmental reasons
How is it regulated?
In the United States, SLES is permitted in cosmetics under FDA oversight, and the FDA has issued guidance on acceptable limits for the 1,4-dioxane contaminant that can result from manufacturing. In the European Union, SLES is allowed in cosmetic products under the EU Cosmetics Regulation, with safety assessments conducted by the Scientific Committee on Consumer Safety setting concentration limits and purity requirements.
How to spot it on a label
On an ingredient list, look for 'Sodium Laureth Sulfate' or the abbreviation 'SLES'; a number in parentheses, such as SLES-2 or SLES-3, refers to the average number of ethylene oxide units added during manufacturing, with higher numbers generally considered milder. If you see 'Sodium Lauryl Sulfate' (SLS) nearby, that is a related but less modified compound and is typically considered harsher. InZoRAH can flag both variants and explain how they differ in a given product's full formula.
What a cleaner swap looks like
Rinse-off products marketed as gentle or sulfate-free often use alternatives such as Sodium Cocoyl Isethionate, Cocamidopropyl Betaine, or Sodium Lauroyl Methyl Isethionate, which produce adequate lather with a lower reported irritation profile. These alternatives tend to be milder on the skin barrier and are widely used in sensitive-skin and baby formulations. Trade-offs can include higher cost and slightly different foam texture.
Questions people also ask about Sodium Laureth Sulfate (SLES)
Is SLES the same as SLS?
No, though they are closely related. Sodium Lauryl Sulfate (SLS) is the unmodified compound, while SLES has been ethoxylated, a process that adds ethylene oxide units to the molecule. This makes SLES less irritating to skin and eyes than SLS, which is why it is preferred in most consumer rinse-off products.
Does SLES cause cancer?
SLES itself is not classified as a carcinogen by major health authorities. The concern sometimes raised relates to trace 1,4-dioxane, a by-product of its manufacture. Regulatory bodies in both the US and EU set limits on this contaminant, and modern processing techniques effectively reduce it to very low levels in finished products.
Can SLES damage hair?
Regular use of SLES-based shampoos can strip some natural oils from the scalp and hair shaft, which some people notice as dryness or frizz, particularly those with coarser or colour-treated hair. The effect is concentration-dependent and largely reversed by conditioning. Sulfate-free formulas are often recommended for chemically treated or very dry hair.
Is SLES safe to use during pregnancy?
There is no strong evidence from regulatory reviews that SLES in standard rinse-off formulations poses a risk during pregnancy. Because it is rinsed off quickly, systemic absorption is minimal. Anyone with specific health concerns during pregnancy should consult a healthcare provider rather than relying on cosmetic ingredient guidance.
Why does SLES appear in toothpaste?
In toothpaste, SLES acts as a foaming agent that helps distribute the product across teeth and gums, suspends loosened debris, and aids in rinsing. Some people with recurrent canker sores find that sulfate-free toothpastes cause fewer flare-ups, though the evidence linking SLES directly to aphthous ulcers remains inconclusive.
What does the number after SLES mean, like SLES-2 or SLES-3?
The number refers to the average count of ethylene oxide units added during the ethoxylation process. A higher number generally results in a milder, more water-soluble surfactant. SLES-2 and SLES-3 are the most common grades found in personal care products, with SLES-3 considered slightly gentler.
Where this came from
FDA cosmetic ingredient and contaminant guidance — Supports the regulatory status of SLES in cosmetics and the agency's position on 1,4-dioxane limits in personal care products
EU Cosmetics Regulation and SCCS safety opinions — Covers permitted use of SLES in European cosmetic formulations and purity standards set by the Scientific Committee on Consumer Safety
Cosmetic Ingredient Review (CIR) expert panel assessments — Supports the general safety conclusion for SLES in rinse-off products at standard concentrations and notes the lower irritation profile compared to SLS
Open Food Facts and product database records — Used to confirm the product categories in which SLES commonly appears on ingredient labels
Original write-up based on public records. Educational information, not medical advice — ingredient records change, so always read the physical label if you have an allergy.
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