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Everything you need to know about SLS and SLES

SLS (Sodium Lauryl Sulfate) and SLES (Sodium Laureth Sulfate) are one of the most common surfactants, which are used in nearly all cosmetics particularly for body care and hair care products. Different Internet sources have contradictory articles about the ways these components affect human body which divides consumers in two groups: “FOR” and “AGAINST”.

Unfortunately, most of the internet resources have unreferenced information without links to scientific articles and studies. In this article, we will talk about the way our skin is structured and the surfactants’ effect on it and also mention results of actual research studies so that we can decide whether it is wise to use products containing these ingredients.

How do surfactants work and how do they interact with our skin?

A surfactant’s cleaning effect is based on its absorption of dirt on the surface and how it separates and stabilizes in a washing solution. The outermost layer of the human skin, also known as the epidermis layer consists of lipids and is the main barrier for retaining moisture and acts as a protective layer from external environment.

“The epidermal barrier serves to limit passive water loss from the body, reduce the absorption of chemicals from the environment, and prevent microbial infection. These defensive functions reside primarily in the top stratum of the epidermis…” – extracted from Structure and function of The Epidermal Barrier by R. Randall Wickett,PhD,and Marty O. Visscher, PhD

When surfactants comes into contact with the human skin, they cause the epidermis layer to swell, making it more penetrable which consequently makes the cleaning process faster and more effective. However, if a surfactant is highly concentrated, it can cause removal of skin lipids and greatly reduce the epidermis’ defensive functions. Hence, it is highly crucial to choose effective surfactant components that will not harm human skin during the development of cosmetics products.

Types of surfactants and their effect on human skin

Depending on the charge formed during dissociation in water, surfactants are categorized as anionic, cationic and amphoteric. Lipid barrier of our skin has low negative charge and that’s why it is safer for the human skin to use anionic surfactants in comparison to cationic as they have a weaker interaction with the surface of the skin. Amphoteric surfactants have the mildest dermatological action and in combination with anionic surfactants they increase lather formation and safety of the cleaning products. The best effect is achieved by using a combination of several different surfactants with various properties.


    Contradictory to popular belief, SLS and SLES are not the same thing. They are two different substances which are part of the same group of alkyl sulfate anionic surfactants. Sulfates are extracted by a method of catalytic restoration of fatty acids, which are extracted from synthetic or floral materials. Surfactants are characterized by their roles as cleaning, emulsifying and foaming agents. However, there is a big difference between SLS and SLES.

    SLS has a poor reputation and is not for nothing. It has a more aggressive irritating action in comparison to SLES. It should be avoided by those with skin allergies, have sensitive skin or young kids. It is also important to mention that there are many unsupported myths that cosmetics with SLS is linked to cancer, though none of them has any solid scientific evidence.

    Now, let’s talk about SLES (Sodium Laureth Sulphate). Based on the results of research that was conducted over many years in scientific labs of Cosmetic Ingredient Review, SLES does not cause any irritation and can be used in cosmetic products in concentration below 50%. SLES is also approved to be used in natural and organic products that are certified by global standards of ECOCERT and COSMOS.

    Cosmetic Ingredient Review (CIR) – independent expert organization made for research of the affects caused by various components used for cosmetics manufacturing. The website of the organization has descriptions and comments on every component used for cosmetics production. All information is freely available.

    Let’s figure it out. Nearly all shampoos contain concentration of cleaning ingredients less than 25% (as you can see it is twice lower than approved concentration of SLES). Apart from that, if the contents of the product have several surfactants it means that concentration of each of them separately is much lower.

    SLES is formulated to be much milder and does not irritate the skin. It is also gentler on the skin and hair without stripping the epidermis layer of excess moisture. Many internet users do not know of this research data and has the misconception that SLES is the same as SLS.

    The next time you pick up your favourite body wash or shampoo, take a look at the ingredients to see if they contain SLS or SLES. If you are considering to make to the switch to gentler formulations, try AIS Cosmetics collection of body care and hair care which are free from SLS and uses SLES to create the foam and lather that we all love.


    *Credits to AIS Cosmetics for original content. Edited by The Min List.