Sodium lauryl sulphate (SLS) is the most widely used synthetic surfactant in foaming consumer products — dish soaps, washing-up liquids, laundry detergents, shampoos, and toothpastes. It is an anionic surfactant that disrupts the skin's natural lipid barrier, increasing permeability to other chemicals, causing irritant contact dermatitis, and exacerbating inflammatory skin conditions. Its ubiquity in both cleaning and personal care products makes it one of the most universal sources of daily skin barrier disruption in modern households.
Where it's found
Washing-up liquid and dish soap universally contain SLS or its slightly milder ethoxylated form, sodium laureth sulphate (SLES). Laundry detergents use SLS and SLES as primary cleaning surfactants. Household cleaners — bathroom, kitchen, and multi-purpose sprays. Shampoos and conditioners — SLS is the foam-generating surfactant in most conventional shampoos. Toothpaste — SLS is present in most branded toothpastes to generate foam and aid oral cleaning. Hand soap and body wash. The cumulative daily exposure from all these product categories means many people have multiple SLS contacts every day.
Routes of exposure
Repeated skin contact during dishwashing, cleaning, and handwashing is the primary route — SLS is a cumulative skin irritant and barrier disruptor with daily exposure. Oral mucosa exposure from SLS-containing toothpaste during brushing. Inhalation of spray mists from SLS-containing cleaning sprays in enclosed spaces. Skin contact from SLS-containing shampoo and body wash residues on skin during showering.
Health concerns
SLS is an established skin irritant and barrier disruptor. It denatures skin proteins, removes natural skin lipids (ceramides and cholesterol), increases transepidermal water loss, and raises skin permeability. In people with atopic eczema, regular SLS contact significantly worsens disease severity. In healthy individuals, repeated daily contact causes subclinical skin barrier impairment over time. SLS in toothpaste is associated with recurrent aphthous ulcers (mouth ulcers) — multiple controlled trials have shown that SLS-free toothpaste reduces the frequency of mouth ulcers in susceptible individuals. The increased skin permeability caused by SLS also amplifies absorption of other chemicals applied to or encountered on SLS-damaged skin — a "co-exposure amplifier" effect relevant to the cumulative chemical burden argument.
Evidence
Skin irritancy and barrier disruption by SLS is among the most thoroughly characterised properties of any surfactant — it is used deliberately as a positive control in skin irritancy research because its effects are so reproducible. The association with mouth ulcers is supported by multiple randomised controlled trials. Exacerbation of atopic eczema by SLS is documented in clinical studies. The co-exposure amplifier effect (increased absorption of other chemicals through SLS-disrupted skin) is supported by permeability studies.
Who's most at risk
People with atopic eczema, psoriasis, or other inflammatory skin conditions are disproportionately harmed by daily SLS exposure. Individuals prone to recurrent mouth ulcers often benefit substantially from switching to SLS-free toothpaste. Infants and young children with developing skin barriers absorb more from skin contact. Professional cleaners and food service workers with intensive daily hand contact with SLS-containing dish soaps are at highest risk for occupational contact dermatitis.
Regulatory status
RegulationSLS is not specifically restricted by concentration limits in cleaning products in the EU, UK, or US. It must be listed on product ingredient labels. The EU Cosmetics Regulation requires it to be declared on personal care product labels. There are no mandatory limits despite well-established skin irritancy. Eco-certification schemes do not typically exclude SLS due to its good biodegradability.
How to reduce your exposure
Wear rubber gloves during dishwashing — this single habit eliminates the primary SLS skin contact route. Choose washing-up liquid formulations based on milder surfactants (alkyl polyglucosides, decyl glucoside, or coco glucoside) if you have eczema or skin sensitivity. Switch to SLS-free toothpaste if you experience recurrent mouth ulcers — this is well evidenced and simple. Use the minimum effective amount of dish soap — most people use far more than necessary, increasing both skin contact and rinse residue.
The nutrition connection
SLS illustrates how a single surfactant present in multiple daily-use product categories creates a cumulative barrier disruption effect that goes far beyond any individual product's contribution. The skin, as a route of exposure for many other chemicals, functions better as a barrier when SLS contact is minimised. Reducing SLS exposure through glove use, product substitution, and dose minimisation is one of the most broadly protective single household chemical interventions available — simultaneously reducing direct irritancy and improving the skin's ability to exclude co-occurring chemicals.