What it is
Sodium lauryl sulfate (SLS) is an anionic surfactant that creates foam and helps distribute other ingredients across the tooth surface.
It is often confused with sodium laureth sulfate (SLES); they are related but chemically distinct.
Why it matters
SLS is a well-documented aphthous ulcer trigger — controlled trials have shown reductions in canker-sore recurrence when users switch to SLS-free toothpaste.
Foam is not a measure of cleaning power. Mechanical brushing does the work; SLS mostly makes brushing feel efficient.
Sensitivity-formulated toothpastes routinely omit SLS because it can worsen the mucosal irritation those pastes are meant to address.
Common uses
- Foaming agent in mainstream toothpaste
- Surfactant in shampoos, cleansers, and body wash
- Industrial degreasers and household detergents
Safety considerations
- Regulatory bodies consider SLS safe at typical toothpaste concentrations for the general population.
- For users prone to canker sores, dry mouth, or sensitive gums, an SLS-free formula is a low-risk, high-value swap.
- Coconut-derived alternatives (sodium cocoyl glutamate, sodium methyl cocoyl taurate) provide gentler foam without SLS.
Where you'll encounter this
- Bathroom — toothpaste, shampoo, body wash, facial cleansers
- Utility — dish soap, laundry, industrial cleaners
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Frequently asked questions
Is SLS in toothpaste unsafe?
Not at typical concentrations for most users. The specific evidence base concerns oral irritation and aphthous ulcer recurrence in a subset of users, not systemic toxicity.
Do I need foam for the toothpaste to work?
No. Cleaning comes from mechanical brushing plus the abrasive and active. Foam is a delivery vehicle; low-foam pastes clean just as well.
What is a good SLS alternative?
Sodium cocoyl glutamate and sodium methyl cocoyl taurate are coconut-derived surfactants that provide gentler foam without SLS's irritation profile.
Editorial references
- Herlofson & Barkvoll — SLS and oral mucosal desquamation (Acta Odontologica Scandinavica)
- Cochrane — Interventions for treating recurrent aphthous stomatitis
Last updated 2026-07-20.