Also on labels as: SLS, sodium dodecyl sulfate, SDS, E487
In one line
A synthetic surfactant that lowers surface tension, allowing water to lift oil and dirt away from skin, hair, or teeth.
What is Sodium Lauryl Sulfate?
Sodium lauryl sulfate is a salt derived from lauryl alcohol, which is itself typically obtained from coconut or palm kernel oil through a series of industrial chemical steps. The resulting white powder or paste is highly water-soluble and carries a strong negative charge. That charge is what gives it its powerful cleaning and foaming action.
What does it do in the product?
SLS works by wedging its molecular structure between oil and water, surrounding grease, grime, and food particles so they can be rinsed away. It also generates the dense, stable lather that many consumers associate with a product 'working.' In toothpaste it helps loosen plaque and distribute active ingredients evenly across tooth surfaces.
Where you usually find it
Toothpaste
Shampoo
Body wash and shower gel
Facial cleansers
Dish soap
Laundry detergent
Is Sodium Lauryl Sulfate something to worry about?
At the concentrations used in rinse-off products such as shampoo and toothpaste, regulatory bodies in both the US and EU have consistently found SLS to be safe for the general population. However, it is a known irritant at higher concentrations or with prolonged skin contact, and some individuals with sensitive skin, canker sore tendencies, or conditions like eczema report worsened symptoms. The concern level is therefore tied closely to how the product is used and who is using it rather than to any broad toxicological hazard.
Who should pay attention
People prone to canker sores (mouth ulcers), as SLS in toothpaste may increase their frequency
Those with eczema, rosacea, or otherwise sensitive or compromised skin barriers
People with a documented contact allergy to SLS or related sulfated surfactants
Individuals managing dry or colour-treated hair, where SLS can strip natural oils and accelerate colour fade
People following a palm-oil-free lifestyle, since SLS is often palm-derived
How is it regulated?
The FDA permits SLS as an indirect food additive, a drug inactive ingredient, and an active ingredient in some over-the-counter categories, with specific concentration limits depending on use. The EU authorises it in cosmetic products under general safety provisions, and it appears on the EU cosmetics ingredient database without an outright ban, though certain rinse-off concentration thresholds apply. Both jurisdictions require manufacturers to demonstrate safety at their intended use level before marketing.
How to spot it on a label
It almost always appears as 'sodium lauryl sulfate' or the abbreviation 'SLS'; the alias 'sodium dodecyl sulfate' is more common in laboratory or pharmaceutical contexts than on consumer labels. If you see both SLS and sodium laureth sulfate (SLES) listed, they are related but distinct molecules — SLES is the milder ethoxylated cousin. Placement near the top of an ingredient list indicates a higher concentration, typically meaning a stronger lather but also greater potential for irritation.
What a cleaner swap looks like
Formulators looking to reduce irritation potential often replace SLS with sodium laureth sulfate, cocamidopropyl betaine, or sodium coco-sulfate, all of which tend to be gentler on skin and hair with a milder irritancy profile. For toothpaste specifically, SLS-free versions using alternatives like sodium cocoyl glutamate are widely available and are the standard recommendation for people who experience frequent mouth ulcers. InZoRAH can scan the barcode of any toothpaste or cleanser to confirm whether SLS is present and flag a gentler alternative.
Questions people also ask about Sodium Lauryl Sulfate
Is sodium lauryl sulfate safe to use every day?
For most adults, daily use in rinse-off products like shampoo or toothpaste is considered safe by US and EU regulators. Problems tend to arise for people with sensitive or compromised skin, or those who experience frequent mouth ulcers. If you notice persistent irritation, switching to an SLS-free product is a straightforward first step.
Does SLS cause cancer?
No credible regulatory body — including the FDA, the EU's Scientific Committee on Consumer Safety, or EFSA — classifies SLS as a carcinogen. It is sometimes confused with sodium laureth sulfate, which has a separate and more nuanced discussion around a manufacturing by-product. The cancer claim attached to SLS specifically is not supported by the mainstream scientific record.
Why does SLS make toothpaste foam so much?
SLS is an anionic surfactant, meaning it carries a negative charge that aggressively reduces surface tension. When you brush and introduce air, this creates a stable foam. The foam itself does not clean teeth — that is the job of the abrasive and fluoride — but many consumers associate heavy lather with effectiveness, which is why manufacturers include it.
Can SLS cause canker sores?
Some clinical evidence suggests that people who are prone to recurrent aphthous ulcers (canker sores) may experience fewer or less severe episodes when they switch to SLS-free toothpaste. The link is not definitively proven for all people, but it is plausible enough that most dental health guidance acknowledges it as a reasonable trial for affected individuals.
Is sodium lauryl sulfate the same as sodium laureth sulfate?
They are related but chemically distinct. Sodium laureth sulfate (SLES) is the ethoxylated version of SLS, which means extra processing steps add ethylene oxide units to the molecule. SLES is generally considered milder on skin, though that process can introduce a trace contaminant called 1,4-dioxane. Both are surfactants, but they carry different risk profiles.
Is SLS vegan and cruelty-free?
SLS is synthetically produced from plant-derived fatty alcohols and contains no animal-derived ingredients, so it is generally considered vegan. Whether a finished product is cruelty-free depends on the brand's overall testing practices, not on SLS itself. Shoppers concerned about palm sourcing should check whether the brand uses certified sustainable palm or coconut derivatives.
Where this came from
FDA inactive ingredients database and OTC monograph guidance — Supports the regulatory status of SLS as a permitted inactive ingredient in drugs and cosmetics at specified concentrations
EU Cosmetics Regulation and the EU cosmetic ingredient database (CosIng) — Confirms SLS is authorised in EU cosmetic products without a category ban, subject to individual product safety assessments
EFSA and SCCS published safety opinions on surfactants — Supports the general finding that SLS at typical consumer product concentrations does not pose a systemic toxicological risk
Dental and oral health literature reviewed by professional bodies — Supports the association between SLS-containing toothpaste and increased canker sore frequency in susceptible individuals
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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