What Is Sodium Laureth Sulfate?

Sodium laureth sulfate, often abbreviated as SLES, is a surfactant. Surfactants are molecules with one end that is attracted to water and one end that is attracted to oil. That dual nature is exactly what makes them effective cleansers: they grab onto oil, sebum (the natural grease your scalp produces), and product build-up, and then rinse away with water, taking the dirt with them.

SLES is derived from lauryl alcohol, which comes from plant oils such as coconut or palm. It is then processed through a reaction called ethoxylation, where ethylene oxide is added to make the molecule milder and more water-soluble than its close relative sodium lauryl sulfate (SLS). That extra processing step is the key difference between the two: SLES is generally considered gentler than SLS, though both belong to the same family of anionic surfactants (surfactants that carry a negative electrical charge).

SLES is one of the most commonly used cleansing ingredients in rinse-off products worldwide. It produces a rich lather, is cost-effective, and has a well-established safety profile. You will find it in shampoos, body washes, and facial cleansers from countless brands, including in our own shampoo and body wash formulas.

What the Science Says

The safety of SLES has been reviewed extensively. The Cosmetic Ingredient Review (CIR) Expert Panel concluded in their 2010 safety assessment that ammonium and sodium laureth sulfates are safe as used in rinse-off cosmetic formulations. The European Union's Scientific Committee on Consumer Safety (SCCS) also permits SLES in cosmetics under EU Regulation 1223/2009, the main European framework governing cosmetic ingredient safety.

So far, so reassuring. But safety at the regulatory level is not the whole story.

Several studies have looked at what SLES actually does to hair and scalp tissue at a structural level. Research by Robbins and Crawford (1991) demonstrated that sulfate-based surfactants cause measurable swelling of the hair shaft when the hair is wet. This swelling, repeated over many wash cycles, stresses the cuticle, which is the outermost protective layer of the hair fibre made up of overlapping scale-like cells. A compromised cuticle means hair is more vulnerable to breakage, colour fade, and moisture loss.

A study by Prottey and Ferguson (1975) found that SLS and SLES both remove skin lipids (natural fats) during washing. While skin and scalp can replenish these lipids over time, repeated removal contributes to dryness and sensitivity, particularly in people with a compromised skin barrier to begin with.

Research published by Bondi et al. (2015) highlighted that individuals with pre-existing scalp conditions such as seborrhoeic dermatitis or eczema reported significantly higher rates of irritation with sulfate-containing shampoos compared to sulfate-free alternatives.

Concentrations matter too. The CIR assessment noted that SLES at concentrations above 2 percent can cause irritation with prolonged skin contact, which is why it is considered acceptable specifically in rinse-off products where contact time is short. In leave-on products, the calculus changes entirely.

Why It Matters for Your Hair

The practical consequences of the science above depend heavily on your hair type, your scalp condition, and how often you wash.

For people with fine, oily hair and a healthy scalp, SLES-based shampoos can work perfectly well. The strong cleansing action removes sebum efficiently and the short contact time during rinsing limits irritation.

For people with dry, porous, chemically treated, or colour-treated hair, the picture is different. Chemically processed hair has a cuticle that is already more open and vulnerable. Each wash with a sulfate-based shampoo can accelerate colour fading by lifting the cuticle further and allowing pigment molecules to escape. Research by Bolduc and Shapiro (2001) confirmed that surfactant choice is one of the most significant variables in how quickly colour fades after dyeing.

For people with a sensitive or dry scalp, eczema, psoriasis, or seborrhoeic dermatitis, repeated exposure to SLES can aggravate existing irritation or trigger flare-ups. Scalp skin is still skin, and the same lipid-stripping effect that dries out body skin applies here too.

For people with naturally textured, coily, or very dry hair, the hair's structure means it is already prone to moisture loss. Anything that further disrupts the cuticle and strips natural oils works against the hair's needs.

Our Position at MyHolyBody

We want to be straightforward: SLES is not a toxic or dangerous ingredient. It appears in our shampoo and body wash because it is a well-established, effective, and regulatory-approved cleanser. We are not going to pretend otherwise.

At the same time, we developed our sulfate-free shampoo because we know that SLES is simply not the right ingredient for every hair type, every scalp, or every person's goals. The founder's own experience with dry, sensitised hair was part of that decision. When the existing tools are not serving people well, you build different tools.

Our sulfate-free shampoo uses a combination of gentler surfactants instead. Cocamidopropyl betaine is an amphoteric surfactant (one that can behave as either positively or negatively charged depending on the environment) derived from coconut oil. Sodium cocoyl isethionate is a mild, fatty-acid-based surfactant that leaves a softer feel on the hair. Together they clean effectively without the aggressive lipid-stripping associated with SLES.

We also include ingredients like panthenol (provitamin B5, which penetrates the hair shaft and supports moisture retention), inulin (a plant-derived prebiotic that supports scalp microbiome balance), and cold-pressed nigella sativa seed oil and argan oil to support the hair and scalp after cleansing.

Our conditioner contains no SLES at all, which is expected for a rinse-off conditioning product focused on replenishment rather than cleansing.

We believe you deserve to know exactly what is in every product and why. That is the whole point of the Holy Guide.

Frequently Asked Questions

Is sodium laureth sulfate the same as sodium lauryl sulfate? No, they are related but different. Sodium lauryl sulfate (SLS) has a simpler molecular structure and is considered more irritating. Sodium laureth sulfate (SLES) has been through an additional processing step called ethoxylation, which makes it milder and more water-soluble, though both are anionic surfactants in the same family.

Is SLES safe to use every day? For most people with a healthy scalp and normal to oily hair, daily use of an SLES-containing shampoo is unlikely to cause harm. For people with a dry, sensitive, or compromised scalp, or with dry or chemically treated hair, daily use may contribute to dryness and irritation over time. How often you wash and your individual scalp health are the deciding factors.

Will a sulfate-free shampoo lather as much as a regular shampoo? Sulfate-free shampoos typically produce less foam than SLES-based formulas. Foam itself does not clean, it is simply a visual byproduct of certain surfactants. Our sulfate-free shampoo cleanses effectively even with reduced lather. It may take a wash or two for your hair and scalp to adjust if you are switching from a high-lather formula.

Does SLES cause hair loss? There is no robust clinical evidence that SLES causes hair loss in people with healthy scalps. Hair shedding sometimes increases temporarily when switching shampoos due to the scalp adjusting, but this is not the same as SLES causing follicle damage or permanent loss. If you are experiencing significant or prolonged hair shedding, that is a reason to speak with a dermatologist rather than solely change your shampoo.

Which MyHolyBody products contain SLES and which do not? Our shampoo and body wash both contain sodium laureth sulfate. Our sulfate-free shampoo and our conditioner do not contain SLES. The full INCI list for every product is published on our website so you can always check for yourself.

Sources

- Cosmetic Ingredient Review (CIR) Expert Panel. Safety Assessment of PEG-Compounds as Used in Cosmetics, including Sodium Laureth Sulfate. International Journal of Toxicology, 2010. 

- European Union. Regulation (EC) No 1223/2009 of the European Parliament and of the Council on Cosmetic Products. Official Journal of the European Union, 2009. - Robbins, C.R. and Crawford, R.J. Cuticle damage and the tensile properties of human hair. Journal of the Society of Cosmetic Chemists, 1991. 

- Prottey, C. and Ferguson, T. Factors which determine the skin irritation potential of soaps and detergents. Journal of the Society of Cosmetic Chemists, 1975. - Bondi, C.A.M., Marks, J.L., Wroblewski, L.B., Raatikainen, H.S., Lenox, S.R. and Gebhardt, K.E. Human and Environmental Toxicity of Sodium Lauryl Sulfate: Evidence for Safe Use in Household Cleaning Products. Environmental Health Insights, 2015. 

- Bolduc, C. and Shapiro, J. Hair care products: waving, straightening, conditioning, and coloring. Clinics in Dermatology, 2001.