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What is Sodium Lauryl Sulfate (SLS)?

Yingdee Chew, MPharm

7 Dec 2017

Here at SkinNinja, we remain determined to share with you world leading expert information so you can make informed choices about your cosmetics and beauty, personal care and skincare products – that means knowing exactly what your ingredients are known to do or what health risks they may pose based on the evidence. In this post, we look at sodium lauryl sulfate…

The Oxford Dictionary definition of sodium lauryl sulfate [1] is:

“a soap-like compound that lathers easily, used chiefly in laundry detergents, cleaning products, and toiletries such as shower gel and shampoo.”

It’s origin comes from sodiumlauryl, an alcohol with twelve carbon atoms from which the compound is prepared, and sulphate.

It’s important to note that sodium lauryl sulphate (SLS) is different from sodium laureth sulfate (SLES), which is used for similar purposes. These two ingredients have the same general formula but differ in chemical properties. We’ll cover sodium laureth sulfate in a separate post!

Bubbles beware!

If it foams, be sure to check for SLS

Products containing sodium lauryl sulfate

SLS is widely used as a surfactant (a substance which reduces the surface tension of a liquid) in shampoos, bath products, soap, shaving preparations and many other personal care products. This ingredient helps the water to mix with oil and dirt, boosting the product’s cleaning effect and creating a lather that consumers identify with effectiveness.

Is sodium lauryl sulfate safe?

For years, there has been information circulating around that has raised questions about the safety of SLS. Let’s take a look at some of these concerns:

Carcinogens: One of the most concerning reports is the link between SLS and cancer. Many people believe that SLS can cause cancer. However, scientific reviews into the matter have found that at this point in time, there is no concrete evidence that validates this link, a finding backed up by the American Cancer Council, along with the Occupational Health and Safety Administration (OHSA) and the National Toxicology Program (NTP). SLS has also not been included in the list of carcinogens compiled by The International Agency for the Research on Cancer (IARC).

Gastrointestinal Toxicant: The European Medicines Agency (EMA) indicated that SLS can cause harmful effects on the upper respiratory tract and stomach. This meaning ingestion of SLS can result in a sore throat, vomiting, nausea and diarrhea. However, the Food and Drug Administration [2] had concluded that SLS does not create an ingestion risk to consumers in the concentrations found in oral care products. For prevention, avoid swallowing your toothpaste or mouthwash. Besides sore throat, vomiting, nausea and diarrhea, a preliminary study by Herlofson & Barkvoll has also concluded that SLS increases the incidence of canker sores in the mouth [3].

Skin or Sense Organ Toxicant:: The European Medicines Agency (EMA) also indicated that exposure to SLS can cause harmful effect to the skin and eyes [4]. According to Dr Stefanie Morris, who is the Dermatologist and Medical Director at European Dermatology London, most people are able to use products such as shampoos and body wash containing SLS without skin irritation. This is because those are rinse-off products where contact time is short. The independent US Cosmetic Ingredient Review (CIR) Expert Panel also found SLS to be safely used in products designed for discontinuous and short use, followed by complete washing from the skin surface.

How can I avoid sodium lauryl sulfate and find sodium lauryl sulfate-free products?

If you do use products containing SLS, you can reduce irritation and minimise health risks by making sure you don’t leave products on your skin for a long time and rinse them off thoroughly.

If you are concerned, choose products with ‘SLS-free’ labels. How to find these? Just download the SkinNinja app, scan whichever products you have containing SLS, and the app will draw from the thousands of products in our cosmetic ingredients database to provide you with a healthier alternative!


  1. Oxford dictionary:
  2. Food and Drug Administration (FDA):
  3. Preliminary study:
  4. Cosmetic Ingredient Review (CIR):

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