SLS – Should you avoid it?

Most people these days have heard of SLS. Many of today’s trendy new products declare, in big, bold letters, to be SLS free, so the reasonable assumption is that it’s an ingredient to avoid. Just like mineral oil. And parabens. I’ve written about why the case against these other ingredients is more marketing smoke than substance, but SLS was one of the earliest ingredients that the Internet turned on and tried to run out of town, like an angry mob wielding torches and pitchforks. So, does SLS deserve its bad reputation?

What is SLS?

SLS, which stands for sodium lauryl sulfate, is a surfactant, or cleansing agent. It was introduced in the 1930s as an alternative to traditional soaps,[1] and has been used in countless shampoos and skin cleansing products ever since. Surfactants work by surrounding small droplets of oil on the hair or skin, trapping them so that they can be washed away with water. Surfactants like SLS are also great at creating a rich, foamy lather in cleansing products.

But is SLS safe?

All surfactants have the potential to be irritating to the skin and eyes. On the surfactant scale, SLS is at the powerful end, meaning it’s very efficient at removing dirt and oil, but it can also remove the skin’s natural oils and damage the skin barrier, leading to irritation if left on the skin for too long. Having said that, the potential for irritation increases with the concentration of SLS in the product, as well as exposure time,[2] so a typical rinse-off product that’s only in contact with the skin for a matter of seconds has a very low potential for causing irritation. 

SLS, and other surfactants, can also be drying, so a good skin cleanser will have added moisturisers to counteract this drying effect. For people prone to dry skin it’s also important to apply moisturisers after cleansing to help replenish moisture levels in the skin.

Recently, there has been some concern that SLS might cause cancer, however a review by the Cancer Council of Australia found that there was absolutely no evidence that SLS, or its close cousin SLES (sodium laureth sulfate), are carcinogens.[3]

In terms of safety, SLS is Generally Regarded As Safe (GRAS) according to the US FDA,[4] and was assessed by the Cosmetic Ingredient Review (CIR) panel[5] and the National Industrial Chemicals Notifications and Assessment Scheme (NICNAS),[6] neither of which found SLS to be unsafe if used according to the label.

When to look for an alternative

For most people, SLS is not likely to cause skin irritation, however if you notice itching, dryness or a ‘tight’ feeling after using a cleanser with SLS you could try switching to a more gentle cleanser. We recommend giving one of these SLS and SLES-free options a try:

QV Gentle Wash

QV Face Gentle Foaming Cleanser

QV Intensive Moisturising Cleanser

QV Intensive with Ceramides Hydrating Body Wash

References

1. Sodium Lauryl Sulfate [Internet]. ChemicalSafetyFacts.org 2019 [cited 2019 Jun 18];Available from: https://www.chemicalsafetyfacts.org/sodium-lauryl-sulfate/
2. Ananthapadmanab–han KP, Yu KK, Meyers CL, Aronson MP. Binding of Surfactants to Stratum Corneum. J Soc Cosmet Chem 1996;47:185–200.
3. Toothpaste (sodium lauryl sulfate) and cancer [Internet]. Cancer Counc. West. Aust.2018 [cited 2019 Jun 18];Available from: https://www.cancerwa.asn.au/resources/cancermyths/toothpaste-cancer-myth/
4. CFR – Code of Federal Regulations Title 21 [Internet]. [cited 2019 Jun 17];Available from: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=172.822
5. Cosmetic Ingredient Review Expert Panel. SLS (sodium lauryl sulfate), sodium laureth sulfate, and ammonium laurethy sulfate ingredient alerts [Internet]. [cited 2019 Jun 18];Available from: http://www.cir-safety.org/sites/default/files/imports/alerts.pdf
6. National Industrial Chemicals Notification and Assessment Scheme L 7. Sodium, ammonium and potassium lauryl sulfate: Human health tier II assessment [Internet]. 2013 [cited 2019 Jun 18];Available from: https://www.nicnas.gov.au/chemical-information/imap-assessments/imap-group-assessment-report?assessment_id=184

Contributor: Josh Townley