Ingredients Glossary: Sodium Lauryl Sulphate (SLS)

22 January 2014


 What Is It? 

Sodium Lauryl Sulphate, or SLS for short, is a surfactant. This means that it may act and be used as a detergent, a wetting agent (so it has less friction on surfaces), emulsifier (keeping two compounds together), and most commonly as a foaming or sudsing agent. 


 Where Does It Come From? 

Originally SLS originates from coconuts and coconut oil (and sometimes Petroleum), unfortunately after the processing and manufacturing it goes through it ends up just about as far away from it's original form as could be. The coconut oil is heated in water with Sodium Hydroxide. This turns it into two fatty acids called Lauric Acid and Glycerin. These fatty acids are then put through a process call hydrogenation and converted into fatty alcohols called Lauryl Alcohols. The Lauryl Alcohol is then turned into Lauryl Sulphate through the process of sulfonation. The Lauryl Sulphate is then reacted with Sodium Hydroxide to create the resulting SLS. (Still with me? It's a long and complex chemistry process and honestly I'm still not 100% able to understand it and can't even begin to go in depth into the hydrogenation or sulfonation processes- chemistry wasn't my forte.)

In its original form it is called Sodium Coco Sulphate (SCS) (see below for more).

 Where To Check For It: 

SLS can be found in everything and anything that is designed to, or claims to be a detergent or foaming! That means it could be present in your floor cleaner, toilet cleaner, your hand wash and even your face wash. A very common place to find it is in Shampoo! It may also be present in your makeup, including foundation, and even in your toothpaste.

 Why It Is Used In Products: 

As mentioned above, it is used for a number of properties including creating the foam in products, as an emulsifier to keep products that have oil and water ingredients, for example, stable and reduce separation. It is also a detergent which is why is is commonly used in cleaning products from household  items to skincare.

 Why You May Want To Avoid It: 

When the chemical SLS undergoes the manufacturing process of 'ethoxylation'* it creates ethylene oxide and 1,4-dioxane two toxic chemical by-products which can be absorbed into your skin and may cause issues with respiration, your kidneys and even cancer. SLS is known to be an irritant and can cause irritated skin and scalp, dryness and inflammation. This can lead to dandruff and other aggravated skincare issues including dermatitis and forms of eczema and psoriasis. SLS in toothpaste is also thought to be a strong cause of many mouth ulcers.

*Ethoxylation is a process that turns SLS into SLES, a milder and more foamy form of SLS. It was thought to be less of an irritant but research shows it still causes the same issues just to a slight lesser extent, plus the process creates the two by-products ethylene oxide and 1,4-dioxane which are just as harmful and carcinogenic.

 Other Names It Can Be Labeled Under: 

  • Sodium Monolauryl Sulfate
  • Sodium Dodecyl Sulfate, 
  • Sodium Dodecane Sulfate, 
  • Lauryl Alcohol, 
  • Hydrogen Sulfate - Sodium Salt,
  • n-lauryl Sulfate Sodium 
  • Sulfuric Acid Monolauryl Ester Sodium Salt
Pheww that's a lot of names!

 Similar But Not To Be Confused With: 


SLS is similar to SLES and ALS. They all have relatively the same function but vary in strength and mildness and have gone through slightly different processes. I will address these chemicals in other posts.

 Safer Alternatives To Use or Look For In Products: 

As mentioned above SLS is originally sourced from coconut oil and then goes through heavy processing.  In its original state the oil can be put through a lower and less chemical laden process that results in what is called Sodium Coco Sulphate in this  state it is found to be a safer ingredient. Yaaay! So you can still have foam and fun! (Although there is plenty of argument about this so its good to do some background on it). 

Hope this was helpful! 

Questions or alterations/extra info? Pop them in the comments and i'll do my best.

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