COTW – Sodium Lauryl Sulfate – SLS

COTW – Chemical of the week

If you’ve read our ‘About Us’ page then you’ll know by now that we both have degrees in Forensic Science and I have gone on to do a MSc in the same subject.

Whilst we have learned the usual fingerprinting and crime scene examination techniques, our degrees are heavily based on chemistry, proved by the fact that M now works in a Toxicology lab.

I’m sure by now you’ll agree when we say we’re obsessed with make up and beauty products…but we’re very aware of the fact that the chemicals in products can have a negative effect on your skin, hair etc 

We think it’s about time somebody decoded all of the scientific jargon and explained what the chemicals are, what they’re used for, where they come from and why they’re potentially bad for you.

We’re hoping to create a series of posts depending on how successful they are, and hope that you’ll understand a bit more when you go to buy products.

We think it’s really important that you read packages sometimes to see what the products contain, and in particular, are reeeeeeeeeally careful when you buy branded products on bidding based websites like eBay.

Whilst they’re usually really careful, I myself have bought products off there and they’ve turned out to be fakes, which means the chemicals used are not regulated and could genuinely be ANYTHING!

Benefit tweeted last week that they analysed a mascara that was a fake, and it turned out to contain petrol and mercury. That is beyond funny, you may as well be pouring petrol into your eye and drinking mercury which could have a SERIOUSLY detrimental effect on your life that the companies do not care about.

It’s time the public fought back a little, so sit back with a cup of tea and hopefully the following will be informative and you won’t be sucked in by any of the hype and advertising from companies flaunting their products.

Sodium Lauryl Sulfate

First up on the list is the ever present Sodium Lauryl Sulfate, or SLS as it is most commonly referred to.

This chemical is found in shower products such as shampoo and shower gel, and shouldn’t be confused with a similar compound called Sodium Laureth Sulfate (SLES).

What is it?

SLS is shown above and in the most basic terms is what makes your shampoo and shower gel lather up, this is termed a ‘surfactant’ and these types of chemicals are found everywhere from your shower gel to your washing up liquid.

Where does it come from?

SLS is very cheap to obtain, normally from inexpensive things such as coconut and palm oils.

For this reason it is used in industry to a massive extent. It can be found in laundry products, engine degreasers, floor cleaners and car washing products. 

What is it used for?

Aside from the ones already mentioned it is used in laboratories as a biocide to stop viruses such as Herpes Simplex Virus and HIV from growing, and to break open cells for the DNA to be analysed.

The pharmaceutical industry uses it in laxatives and dissolvable aspirins.

As for household usage, not only is it found in lathering products such as shampoo, but also shaving gel and toothpaste.

A study showed that the use of SLS in a toothpaste has actually produced a significant result of causing the recurrence of mouth ulcers or canker sores (whichever you call them!)

Basically, it doesn’t sound like a nice chemical that you want to be washing your dishes, showering in or cleaning your teeth with does it?

What are the effects?

From a cosmetic point of view, it can increase the amount of hair you lose per day and as it works by helping the oil and grease on your head to mix with water, can cause your hair colour to fade much faster.

Whilst it does irritate some people’s skin, it generally doesn’t irritate them too greatly unless they have extremely sensitive skin such as individuals with chronic skin hypertensivity. 

The concentration of the chemical in household products is too low to cause any damage (but I’m sure if you got your hands on some engine degreaser it would be a different story!)

The claims that it is a carcinogen (cancer causing) are completely unfounded, and most research has only found them to be an irritant which we have already discussed.

I have double checked this on the International Agency for Research of Cancer (IARC).

There might however be some truth to it reacting with other chemicals and producing cancer causing chemicals as a by-product but the research isn’t clear.

So…what to do??

Using the chemical is of course completely up to you.

I would advise not using too many of the products that contain SLS to err on the side of caution.

Too much of it and it will irritate your skin, but as we’ve been using it this long without any problems and scientific research hasn’t caused a ban on the chemical I don’t believe that it is too harsh.

Companies however are sitting up and taking note of the whispers of the public and producing products that are ‘SLS free’

I recently bought a shampoo and conditioner set from both Naked and Tigi, both are SLS free.

I will be doing a review on them both shortly, and whilst they are noticeably harder to lather, they still do the job perfectly well. My hair is still in as good condition as it was before, and I assume will only improve as I continue using them.

Something to note at this point is that as SLS is derived from coconut and palm oils, it is considered ‘natural’ and therefore even though it goes through a substantial chemical process, can still be found in ‘natural’ and ‘organic’ products…Cheeky!

Products that are free from SLS do normally cost more, but shouldn’t differ in any way from normal products, even hydrating, volumising etc shampoos can still be found without containing SLS.

L’oreal have recently brought out their own line of EverPure products which do not contain sulfates and are offering a range of smoothing, hydrating and volumising hair products that I may have to take a look at!

I hope this post has been informative and not too much hard work to understand!

Please let us know what you think, and whether you’d be interested in more of these type of posts.

We have a few more posts similar to this one lined up, and if there’s any chemicals in particular that you’d be interested in reading about just let us know 🙂

L xxx

Here’s our other posts in the same topic:




  1. shannen
    February 26, 2012 / 3:23 pm

    I'm studying chemistry in school so a lot of these words actually mke sence to me :)Really interesting post,Shannen Xx

    • C.S.I Beauty Blog
      February 27, 2012 / 10:39 am

      Thank you Shannen 🙂

  2. Mittens
    February 26, 2012 / 10:00 pm

    Really informative post, its always worrying how little people (myself included) know about what's in beauty products … (I studied forensics it was great fun 🙂 )

    • C.S.I Beauty Blog
      February 27, 2012 / 10:40 am

      Thank you 🙂 if you don't mind me asking, what do you do now? It's surprising what you can find in a shower gel when you read the contents, sounds like the chemistry lab!

    • Mittens
      February 28, 2012 / 9:43 am

      Dont mind you asking 🙂 Unfortunately I dont work in Forensics (due to a lack of jobs). I work in a Pharma company in Pharmaceutical development so basically developing novel drugs and helping bring them to the commercial market…its quite fun. 🙂

    • C.S.I Beauty Blog
      February 28, 2012 / 10:47 am

      Ah right! Yeah it's a bit of a tricky job market, I'm hoping once I've finished the MSc things will be better…but it's not looking likely! Finger crossed tho 🙂

    • Mittens
      February 28, 2012 / 2:32 pm

      I think a MSc will def help. Wish you luck 🙂

    • C.S.I Beauty Blog
      March 1, 2012 / 9:25 am

      Thank you 🙂

  3. Dragon Mommy
    February 27, 2012 / 1:32 pm

    Great post, thanks for advising us!Holli

    • C.S.I Beauty Blog
      February 27, 2012 / 7:30 pm

      No problem, glad you enjoyed it 🙂

  4. Beauty Bird
    September 5, 2012 / 9:21 pm

    Thanks for linking me to this post! Really informative, would love to see more of these! x

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