Sodium lauryl sulfate: how bad is it?

Updated: May 7, 2020

Sodium Lauryl Sulphate (a.k.a. SLS) is one of the most talked about but misunderstood cosmetic ingredients. Alongside parfum, parabens and PEG compounds, SLS is considered of The Dirty Dozen ingredients to avoid if greenwashing your life is top priority. And when you google sodium lauryl sulfate, you are bombarded with terrifying questions that other people have asked, like what are the side effects? and is sodium lauryl sulfate bad for you? as well as does SLS cause acne? 

Despite the mass worry surrounding sodium lauryl sulphate, it’s widely used and you can most probably find it in most of your favourite foaming products, so it is difficult not to wonder why SLS has such an infamous reputation. In this post you will be able to understand why this ingredient is used in our products, the health concerns associated with it and the studies in which these beliefs have stemmed from, so that you can work out if it is worth ditching sodium lauryl sulphate from your routine for good.

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What is sodium lauryl sulfate (SLS)?

Sodium lauryl sulfate is pretty much the same ingredient as sodium laureth sulfate (SLES). Both of these ingredients are formed by mixing lauryl alcohol and sulphuric acid together. Sodium carbonate is used to neutralise the reaction and create sodium lauryl sulfate, and ethylene oxide is used to create sodium laureth sulfate. 

As well as a synthetic ingredient, it can also be derived from natural resources, sodium lauryl sulphate can come from both coconut and palm oil as they both contain rich sources of lauric acid. 

Where can you find it? Pretty much anywhere. SLS has been used since the 1930s to help create a foamy texture in personal products such as shampoo, toothpastes and mouthwashes, bodywashes, liquid soap and bath bombs, including household cleaning products like laundry and dishwasher detergents. It is also found in pet care products and the FDA have approved its use to thicken and emulsify some foods. 

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Other names for sodium lauryl sulfate include:

  1. Sodium salt

  2. Sodium dodecyl sulfate

  3. Monododecyl ester

  4. Sulfuric acid

  5. Aquarex methyl

Why is it used in our products?

Sodium lauryl sulphate plays a soap role in these products and is cheap for manufacturers to use. The detergent quality of this ingredient encourages a product to lather when water is added to it. Hello bubbles. Sodium lauryl sulfate also acts as a surfactant meaning it breaks down the surface tension between water and oil molecules, meaning a better product interaction with the skin and hair.

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Is sodium lauryl sulfate dangerous?

In the 1970s a scandal emerged revealing that some household shampoos were contaminated with traces of the carcinogenic ingredient, nitrosamine. Ethanolamine lauryl sulfates were confirmed to be the cause for this and the necessary action was taken. There was a handful of research that was carried out in the 1980s and 90s to assess how carcinogenic SLS could be, but no evidence was found for it to be true. Meanwhile The Occupational Safety and Health Administration (OSHA), The Nation Toxicology Program (NTP) and The International Agency for Research on Cancer (IARC) have all rated sodium lauryl sulphate as non-carcinogenic.

The studies on sodium lauryl sulfate in the new millennia held a different theme: to prove how drying SLS was for the skin. Some examples include one trial conducted in 2006, to calculate skin irritation after the exposure to SLS, by measuring the transepidermal water loss (TEWL) of the skin. The younger test subjects showed higher changes in TEWL than the older group when a 2% neat concentration of SLS was applied to the skin’s surface.

Dr Chris Van Tulleken also carried out an experiment, by exposing the same area of skin to a diluted concentration of SLS for 6 hours, every day, for 3 weeks. Chris’s water loss tripled during this time and was “roughly equivalent to being halfway to completely losing the top layer of his skin.”

But these findings do not guarantee the outcome of using sodium lauryl sulphate in our personal products. These studies often use much higher concentrations of SLS compared to the amount we would usually find in our shampoos, bubble bath and bath bombs. The various studies that are published on this topic, show that sodium lauryl sulphate ingredient can certainly irritate the skin if left on it for long periods of time, but the type of products SLS is usually added to, like shampoos and toothpaste, require you to rinse off/out after a minute anyway.

Another trial highlighted the level of eye irritation that can be caused when in contact with neat sodium lauryl sulphate, but we can also say the same for thousands of other FDA-approved ingredients.

So, if SLS is such a common ingredient and been used for nearly a century in manufacturing, why are there so many companies marketing “sulphate-free” products? The majority of headlines indicating that SLS is dangerous and an irritant are routinely orchestrated by the companies trying to sell their ‘natural’ products to fashionable consumers that want to make cleaner choices.

Animal welfare and environmental concerns

Human toxicity is not the only issue raised when sodium lauryl sulphate is discussed, as this ingredient is often tested on animals during medical trials. The derivates that SLS is produced from, also posts a negative impact on the environment. Sodium lauryl sulphate can be derived from petroleum resources – this industry requires the mining and refinery of crude oil to make its products. Palm oil is another natural derivative of SLS – its thousands of plantations are the leading cause of deforestation in Malaysia and Indonesia. 

Screenshot via Rainforest Rescue


Fact: sodium lauryl sulphate will most likely not irritate your skin due to its low toxicity, and is non-carcinogenic despite the drastic claims made over 40 years ago. If swallowed, expect a stomach ache. If your eyes come into contact with a neat concentration of sodium lauryl sulphate, then it is definitely a good idea to seek medical advice. If you leave your shampoo or body wash on your skin for hours longer than necessary, then you will certain experience dryness and discomfort.  So be mindful and don’t swallow your toothpaste or mouthwash and always rinse off your hand soap and shampoo thoroughly.

On the contrary there is no harm in trialling an SLS-free lifestyle for yourself if you:

  1. notice a skin reaction when you use household cleaning/personal products containing SLS 

  2. are concerned with the environmental and animal welfare issues surrounding the manufacturing of sodium lauryl sulphate

  3. are experiencing a dry, itchy scalp

  4. or are suffering with dry skin or chronic conditions such as eczema, psoriasis or dermatitis

  5. only want to use 100% natural skincare/cleaning supplies 

3 things to try if you plan to go SLS-free

Convert your conditioned mentality that getting clean does not have to involve a product that foams and bubbles.

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Use 100% natural soaps such as Castile  and Black African Soap which are free of foaming agents and biodegradable. 

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Pinterest offers a range of homemade shampoos (and body scrubs, butters and soap) recipes to try at home, such as ¼ cup of apple cider, 16 cups water and a few drops of essential oil to help clean your hair and scalp.

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Have you gone sulphate free? What are your thoughts on SLS? Start the discussion and comment below, or find me on social media.

#toxicskincareingredients #cleanbeauty #dryskin #greenwashing #sodiumlaurethsulfate

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