What's the difference between Sodium Lauryl Sulfate (SLS) and Sodium Laureth Ether Sulfate (SLES)


While the names of these two common cleaning agents may seem interchangeable, there is a distinction between the two — and a reason why you should opt for products that use SLES over those that use SLS.

Reading a cleaning product label often feels like cracking a code. The ingredient list scrolls with chemicals that many of us can’t identify, and just the thought of researching them all is daunting. Yet it’s important to know what you’re really coming into contact with, whether you’re using the product to wash your clothes or dishes, or applying it directly onto your hair or skin.

One of the first ingredients you’ll see listed on many cleaning and personal-care products, from detergents to toothpaste, is Sodium Lauryl Sulfate (SLS). This common chemical is a surfactant, which means it lowers the surface tension of water and helps products cleanse and lather when used. Many hand soaps, face washes and shaving creams owe their foaming quality to SLS.

But there’s another ingredient with a confusingly similar name: Sodium Laureth Ether Sulfate (SLES). You may also see it simply called Sodium Laureth Sulfate, with “Laureth” serving as a contraction for the words “Lauryl” and “Ether.” Like SLS, SLES is used for its emulsifying abilities and serves as a super-effective detergent and cleaner.

While the names of these two cleaning agents and their functions may seem interchangeable, there is a distinction between the two — and a reason why you should opt for products that use SLES over those that use SLS.

The Key Difference

Sodium Lauryl Sulfate (SLS) is actually the parent chemical that is modified to make Sodium Laureth Ether Sulfate (SLES). It’s created by reacting lauryl alcohol with petroleum or with coconut or palm oil. To derive SLES from SLS, a process called ethoxylation (in which ethylene oxide is introduced) has to take place. This process is key because it turns SLES into a safer, less harsh chemical than its predecessor, according to the Campaign for Safe Cosmetics.

Studies thus far have debunked claims that parent chemical SLS can cause chronic health effects, according to a 2015 review published in Environ Health Insights, but is it well-known as a skin and eye irritant. That’s not exactly a quality you seek out in your laundry detergents and body products. Though a small concentration is unlikely to spur contact dermatitis — a.k.a. an obnoxious rash — you can’t determine the amount of SLS in each product when it’s not included on the label. And SLS is used in a wide range of concentrations: 0.01% to 50% in cosmetics and 1% to 30% in cleaning products, according to the 2015 study.

SLES, on the other hand, does the same cleaning and emulsifying job but is far less likely to aggravate your skin (phew!).

Shop Smarter

Switching to better-for-you detergents is just the start. Because SLS is used so widely in personal-care products and cosmetics (mascara, styling gel, bubble bath, you name it), it’s smart to do just a bit of research using a tool that makes it simpler for you. Begin by searching for products within the EPA Safer Choice database, or use the Environmental Working Group’s Skin Deep Cosmetics Database. While you’re at it, here are more health and beauty product swaps you should consider making.

Image credit: Keith Williamson/Flickr