SLS is the bad boy of the pack. It’s an ingredient in all sorts of products from toothpastes to shampoo to food. Basically it makes life cheaper and easier for product manufacturers who appear to care little for the negative effect it has on atopic people who use their products. There are plenty of alternative chemicals which do the same thing as SLS so it’s just not necessary.
Sodium Lauryl Sulphate is an emulsifier which keeps other chemicals in suspension in products. It’s a truly useful ingredient from the manufacturer’s perspective but a potentially hazardous chemical for many people. It strips fat out of the skin barrier, an essential layer just below the skin surface which controls how much water evaporates from the skin. When enough fat has been stripped out a point is reached where the water loss is so high the person feels their skin is dry.
That’s when the irony really shows. People with dry skin use moisturisers, many of which contain SLS that removes fat from skin allowing more water out increasing the sensation of dry skin. Moisturizers used to moisturize skin can lead to skin dryness; ironic, isn’t it? The manufacturers are happy as drier skin requires even more moisturiser. Great for sales profits.
The really tragic part comes when doctors recommend or prescribe SLS-containing products for use on dry skin. I used to be accused of scare-mongering when I said things like that. Now I can cite an evidence-based medical article by Moncrieff and colleagues in the highly regarded Clinical and Experimental Dermatology journal (2013; 3: 231). They categorically state that no emollient product containing sodium lauryl sulfate should be used by any patient with dry skin.
People often ask why eczema has become so prevalent. This is one of the reasons. Dry skin happens before eczema shows. If SLS-containing products are used on the initial dry skin a situation called Product Maintained Dermatitis can develop. To most people that is called Atopic Eczema. A staggering twenty percent of our babies are diagnosed with it in their first year of life! Emulsifiers like SLS are one of the components which need to be considered in this eczema epidemic and the recent research evidence should be a high priority for those providing advice on eczema. Most such people believe their advice is about how to manage eczema. SLS helps explain why what they are actually doing is to maintain eczema.
That’s a deliberately provocative statement provided to induce debate. I like to hope that any medical person who is suggesting the use of products containing SLS on dry skin would examine the Moncrieff article before taking part in that debate. It would be lovely if they did. Until then those of us who know how to end eczema must utilise things like blog posts.
Check the ingredient list on all your products for Sodium Lauryl Sulphate. There are many products which do not. It would make sense to use those, wouldn’t it?
Dr Harley Farmer PhD BVSc(hons) BVBiol(path) MRCVS