Why Is SLS Harsher Than Other Surfactants?

[Winterwitch]

Hi guys, something that's always made me curious about why SLS is so harsh is that other surfactants (saponin/soapnuts, decyl glucoside) if they work through the same mechanism. Is SLS just more concentrated or effective as a surfactant?

It's not that I'm doubting the generally accepted idea that soapnuts and decyl glucoside are less harsh. I've personally observed in my own hair that shampoos containing decyl glucoside as opposed to SLS make my hair feel less stripped. Could that just be coincidence, perhaps the DG shampoos just contain other ingredients that restore more moisture than the SLS shampoos I've used don't have? Or does DG just not as effectively remove all oils from the hair as SLS does?

[pinutzz]

They work through a similar mechanism, but not exactly the same. People usually distinguish between cationic, anionic, amphoteric and nonionic surfactants. I found a good explanation here:
http://www.nenonatural.com/hair-blog/surfactants-explained-anionic-vs-non-ionic-vs-cationic-vs-amphoteric-als-vs-sls

[Winterwitch]

They work through a similar mechanism, but not exactly the same. People usually distinguish between cationic, anionic, amphoteric and nonionic surfactants. I found a good explanation here:
http://www.nenonatural.com/hair-blog/surfactants-explained-anionic-vs-non-ionic-vs-cationic-vs-amphoteric-als-vs-sls

Thank you so much!
I kept googling things like "sls vs decyl glucoside" and didn't get anywhere, hahah. So thank you very much, I had no idea about this!

[Robi-Bird]

The primary skin related issue, from my understanding is that SLS is sulfates and the remains of that process are in SLS and it is a known cause of contact dermatitis. All surfactants have the ability to be harsh. A good formula for a shampoo will typically include three surfactants, all at levels below the common risk of sensitization or irritation.

[lapushka]

In most EU shampoos (in Belgium anyway), you'll find SLES & CB. Only Pantene & Herbal Essences have *and* SLS & SLES & CB (cocamidopropyl betaine); that's why it's so great for my SD (seborrheic dermatitis). I need the harshest shampoos on the market to keep it at bay, and somehow it works.

[renia22]

Keep in mind when you hear things like "SLS is the harshest", it's because these ingredients are tested in isolation, and include things like 24 hour patch tests, and these ingredients are not used this way in real life. Concentrations used, mildness boosters, conditioning agents, ph adjusters..all of these things will determine whether a formula is "harsh" or not. Also someone might have a skin reaction to an isolated ingredient in a 24 patch test, but if the same ingredient is used in a properly formulated shampoo and rinsed out, they could be fine with the ingredient. Also, to further complicate things, when you see two or more sulfates, it makes the formula milder, not harsher.

There's a lot of conflicting info to muddle through. A Trichologist at Aveda explained it that way as well. Basically a lot of it has to do with marketing and advertising. When asked why Scalp Benefits, which has been "sulfate free" since 1996 wasn't advertised as such, explained that you have to look at overall formulas and not individual ingredients, and that "sulfate free" is a meaningless term. So maybe "SLS" (isolated ingredient) is "harsher" than other surfactants, but that doesn't mean the finished product will be.