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Cosmetic ingredient

Sulfates (SLS and SLES)

The main cleansing and foaming detergents in most shampoos Also on labels as: sodium lauryl sulfate, sodium laureth sulfate, ammonium lauryl sulfate

Reviewed on

What it does

Sulfates are surfactants — detergents with one end that grabs oil and another that mixes with water, so oil and dirt rinse away. Dermatology reviews describe sodium lauryl sulfate (SLS) as a strong cleanser that foams well and is often used in shampoos for oily hair, and sodium laureth sulfate (SLES) as a good cleanser suited to normal to dry hair.

Sulfate-free shampoos

"Sulfate-free" shampoos use other, often milder, detergents. People with very dry, curly or colour-treated hair, or a sensitive scalp, often prefer them. That's a reasonable personal choice — but we found no clinical trial comparing sulfate-free and sulfate shampoos for hair health.

Cautions

  • Sulfates can irritate sensitive skin, especially at higher concentrations — patch tests show SLS above about 2% irritates normal skin over 24 hours. Shampoo is rinsed off quickly, but if your scalp stings, try a gentler formula.
  • Even medicines include it: the UK leaflet for Nizoral 2% shampoo warns that its SLES content may cause stinging or burning.
  • Claims that sulfates cause hair loss or cancer aren't supported: a toxicology review found no evidence that SLS causes hair loss and no scientific evidence that it is a carcinogen.

How strong is the evidence?

Evidence: Cosmetic

Changes how hair looks or feels; not a treatment for any condition.

What we know comes from toxicology and irritation testing rather than hair-health trials. Rated "cosmetic": sulfates clean well; whether you prefer them is about how your hair and scalp feel.

Not medical advice. This guide is general information from the sources listed, not a diagnosis or a substitute for a pharmacist, GP or dermatologist. If you are worried, or symptoms are severe or not improving, get advice. Read our health information policy.

Sources

  1. D'Souza P, Rathi SK. Shampoo and conditioners: what a dermatologist should know? Indian J Dermatol 2015 pmc.ncbi.nlm.nih.gov
  2. Gavazzoni Dias MF. Hair cosmetics: an overview. Int J Trichology 2015 pmc.ncbi.nlm.nih.gov
  3. Bondi CA et al. Human and environmental toxicity of sodium lauryl sulfate. Environ Health Insights 2015 pmc.ncbi.nlm.nih.gov
  4. emc – Nizoral Anti-Dandruff Treatment 2% Shampoo (SmPC) medicines.org.uk