SLS (Sodium Lauryl Sulfate) is a synthetic cleanser that made its way into shower gels, shampoos and toothpaste due to three properties: cheap, effective and abundantly foaming. Foam is equated by many people with thorough cleansing. That is a learned association, but not proof that it is better for the skin.
We made a different choice. No sulfates in our products, not as a compromise but as a position. SLS, SLES and related substances are on our published NO-list.
We use saponified vegetable oils as cleanser. That process naturally produces glycerin, a substance that retains moisture and keeps the skin supple. Effectively cleansed, with the skin barrier intact. SLS cleansers do not produce this glycerin by-product.
What is SLS?
SLS stands for Sodium Lauryl Sulfate. It is a synthetic cleanser (surfactant) that is widely used in shower gels, shampoos, toothpaste and household cleaning products. Its popularity comes from its strong foaming effect and low cost.
On INCI lists you will find SLS as "Sodium Lauryl Sulfate". Related substances are SLES (Sodium Laureth Sulfate), ALS (Ammonium Lauryl Sulfate) and ALES (Ammonium Laureth Sulfate).
SLS is found in more than 90% of conventional shower gels and shampoos.
What does SLS do?
SLS is a surfactant that removes grease and dirt from the skin. It works by lowering the surface tension of water, allowing water to mix with oil. This makes it an effective cleanser.
The disadvantage: SLS makes no distinction between dirt and the natural oils that protect your skin. It removes both, which can damage the skin barrier.
What does SLS do to your skin?
SLS is approved for cosmetic use (EU and FDA), but can cause problems for some people:
- -Dryness due to removal of natural oils
- -Irritation with prolonged contact or high concentrations
- -Aggravation of existing skin problems (eczema)
- -Sensitivity with a weakened skin barrier
Studies show that daily use of SLS-containing products measurably increases transepidermal water loss (TEWL), an indication of reduced barrier function.
SLS vs. SLES: what is the difference?
| Property | SLS | SLES |
|---|---|---|
| Full name | Sodium Lauryl Sulfate | Sodium Laureth Sulfate |
| Irritation potential | Higher | Lower (ethoxylated) |
| Foaming | Strong | Strong |
| Commonly found in | Toothpaste, industrial products | Shower gels, shampoos |
SLES is slightly milder than SLS because it has undergone an ethoxylation process. However, both are sulfate-based cleansers.
What are the alternatives to SLS?
Saponified oils
Coconut oil and olive oil saponified into a mild cleansing product with glycerin.
Mild surfactants
Cocamidopropyl Betaine and Sodium Cocoyl Isethionate are gentler than sulfates.
Glucoside-based
Coco-Glucoside, derived from sugar and coconut oil.
Why doesn't La Fuente Mía use SLS?
We do not use SLS, SLES, ALS or other sulfate cleansers. Our body bars cleanse with saponified plant oils. A traditional method that cleanses gently and cares for the skin.
This choice is on our NO-list: a published list of ingredients we will not use under any circumstances.
Last updated: 2026-03-06