Sodium Laureth Sulfate
An ethoxylated version of SLS that is slightly gentler on skin but still a strong foaming cleanser. It is the most common main surfactant in US drugstore shampoos.
Curly Girl note: Milder than SLS but still a sulfate, so strict Curly Girl lists avoid it.
About Sodium Laureth Sulfate
Sodium laureth sulfate (SLES) is made by ethoxylating lauryl alcohol before it is sulfated. The extra ethylene oxide units make the molecule larger and a little less irritating to skin than sodium lauryl sulfate, which is why SLES became the default cleanser in mass-market shampoos and body washes.
For hair, the practical difference from SLS is smaller than for skin. SLES still removes oil, styling products and many silicones very efficiently and produces plenty of foam. On curly, coily and relaxed hair that can mean dryness, frizz and more tangles after washing, especially with frequent use or long, porous lengths.
The Curly Girl Method treats SLES as a sulfate to avoid. If your routine includes non-soluble silicones, waxes or heavy butters, an occasional wash with an SLES shampoo can reset build-up, then follow with a deep conditioner. Many people with low porosity hair find an occasional clarifying wash helps products absorb again.
The label may show it as sodium laureth sulfate, SLES or with a number (laureth-2, laureth-3) describing the degree of ethoxylation. Like other ethoxylated ingredients, it is manufactured with steps that remove the 1,4-dioxane by-product. The Cosmetic Ingredient Review panel has assessed it as safe as used in rinse-off cosmetics; it can irritate sensitive skin at high concentrations.
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
- sles
- sodium lauryl ether sulfate
- sodium laureth sulphate
- sodium laureth-2 sulfate
- sodium laureth-3 sulfate
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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