Sodium Lauryl Sulfate
A strong anionic surfactant that makes shampoo foam and lifts oil, product build-up and dirt. Very effective, but it can leave curly and coily hair feeling stripped.
Curly Girl note: A strong sulfate cleanser — the classic ingredient the Curly Girl Method was built to avoid.
About Sodium Lauryl Sulfate
Sodium lauryl sulfate (SLS) is an anionic surfactant made from lauryl alcohol, usually sourced from coconut or palm kernel oil. In a shampoo its job is simple: it surrounds oil, silicones, styling polymers and dirt so they rinse away with water, and it creates the rich lather many people associate with clean hair.
That cleaning power is also its downside for textured hair. Curly and coily strands already struggle to get scalp oil down the length of the hair, and a strong sulfate removes much of the little that is there. Many people with 3c–4c hair notice their hair feels squeaky, tangly or rough after an SLS shampoo, especially if they wash often.
The Curly Girl Method lists SLS as an ingredient to avoid. People who use silicones, heavy butters or lots of gel sometimes keep an SLS shampoo for occasional clarifying, and many clarifying and salon shampoos rely on strong anionic surfactants for exactly that reason. If you have relaxed hair, a strong shampoo used now and then is common practice, but a gentler cleanser is easier on fragile ends for regular washing.
On safety, the Cosmetic Ingredient Review panel has assessed SLS as safe in products that are rinsed off, with lower limits for leave-on use. It can irritate sensitive skin at higher concentrations or with long contact, so rinse it out thoroughly.
How our checker rates it
| Mode | Rating | Why |
|---|---|---|
| Curly Girl | Avoid | Harsh sulfate — strips natural oils. Not allowed in the Curly Girl Method. |
| Relaxed hair | Caution | Strong cleanser — good for clarifying or as a neutralizing shampoo after a relaxer, too stripping for every wash. |
| Low porosity | OK | No concerns for this mode. |
| Protein-sensitive | OK | No concerns for this mode. |
Ratings assume it is listed near the top of the label. After the first preservative or fragrance (likely 1% or less) most cautions soften.
What harsh sulfate ingredients do
Strong detergents that lift oil and product build-up very effectively — and also strip the natural oils that dry, coily hair needs.
Also listed as
- sls
- sodium dodecyl sulfate
- sodium lauryl sulphate
Similar ingredients
Sources
Last data update:
- Cosmetic Ingredient Review (CIR). Ingredient safety assessments. Safety assessments for cosmetic ingredients cited on ingredient pages.
- Robbins CR. Chemical and Physical Behavior of Human Hair. 5th ed. Springer; 2012. Reference text on hair structure, surfactants, conditioning agents, protein, heat and chemical treatments.
- Massey L, Chiu M. Curly Girl: The Handbook. Workman Publishing; 2011. Origin of the Curly Girl Method rules (no sulfates, no non-soluble silicones, no drying alcohols).
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