What Is SLS “Sodium Lauryl Sulfate” in Soap And Toothpaste?


What Is SLS?

What is SLS exactly? SLS, or sodium lauryl sulfate, is a common ingredient in beauty products, washes, toothpastes and even cleaning products.

When we use a wash or beauty product on our skin, it’s probably a liquid made of a water phase and an oily phase. As we know, oil and water don’t mix, so something is required to keep the ingredients together.

That something is called a surfactant. A surfactant allows the oil and water molecules to bind together. It’s also what’s found in soaps and detergents so we can wash our oily faces or dishes with water and get the grime to disappear.

Sodium lauryl sulfate is a surfactant, and its efficacy, low cost, abundance and simplicity mean it’s used in a variety of cosmetic, dermatological and consumer products.

Is SLS Harmful?

Our skin’s outermost layer is specially designed to keep harmful stuff out. This is where a surfactant can cause problems. Using a chemical that weakens this defense mechanism can potentially cause our skin harm.

Some surfactants are more irritating to our skin than others. For something to be harmful, irritant or allergenic, it has to fulfill two criteria. It has to have been found in studies to irritate human skin, and it has to have the ability to penetrate the skin. SLS ticks both of these boxes.

SLS Research

Researchers from Germany tested 1,600 patients for SLS irritancy and found 42 percent of the patients tested had an irritant reaction. Another study, on seven volunteers over a three and a half month period,
found regular contact caused irritation. The irritation subsided once the skin was no longer exposed to SLS. A different study found the warmer the water used with SLS, the more irritating it will be. In fact, SLS is so known to cause irritation, it’s used as a positive control in dermatological testing. That is, new products being tested to see how irritating they might be to human skin are compared to SLS – something we know definitely to be irritating.

If a person is sensitive to SLS, they might find the area that has been in contact is red, dry, scaly, itchy or sore.

Who Should Avoid SLS?

People with a history of sensitive skin, hyper-irritable skin and patients suffering from skin conditions such as atopic dermatitis (eczema), rosacea and psoriasis are best to avoid products containing SLS.

There are many safer alternatives available (look for fatty alcohol ethoxylate, alkyl phenol ethoxylate or fatty acid alkoxylate on the label). If you think it might be SLS causing a skin irritation, stop the use of the product and ask your pharmacist or GP for advice.

Skin care products also have hotline numbers on the packaging that can be contacted to report adverse effects.

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