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Curly Nikki

The Truth About….

By January 27th, 202112 Comments

Sodium Lauryl/Laureth Sulfate- the cleansing agent in many commercial shampoos.

I ran across this article in a thread on and asked JC to do her thang! The article claims that “soaps and shampoos containing sodium laureth sulfate can lead to direct damage to the hair follicle, skin damage, permanent eye damage in children and even liver toxicity”. Find her response below:

This article is yet another example of poor interpretation of science. Here are the facts. SLS (both laureth and lauryl) is a foaming detergent. It is used to create the suds that people like in shampoo and toothpaste. It is a cheap and effective cleanser.

It is an irritant(this is why you don’t want shampoo in your eyes). The tear-free formula shampoos and shower gels for kids generally do not contain SLS (not always but often). It is not carcinogenic but has sometimes been found to be contaminated with a different carcinogenic chemical. A small number of people are sensitive to SLS and it can cause dermatitis (inflammation of the skin).

It is often reported that SLS shampoos can dry hair and break it. Yes some people find SLS to be drying, this is usually fixed by following up a shampoo with a conditioner so that you can correct the charge on the hair and help the cuticle to lie back down. SLS specifically lauryl sulphate is used in the lab to break down proteins. You would however need a significantly concentrated amount than what you get in a shampoo bottle or 20.

Lastly the article says SLS mimics oestrogen in the body. Now my head was spinning and I couldn’t quite grasp this. What? How? What kind of chemistry? At the risk of my computer shutting down on me for sheer madness, I decided to push all my reservations aside and look for any scientific paper that says this. Needless to say, I didn’t find any ( I did find 10 similar sites though to this which all state this as a fact without any references). Interestingly, there were topics about adding SLS (in an active concentration) to help fight HIV infection which is new to me, so my search was not entirely fruitless.

In the end, you can choose to use SLS-free shampoos if you are concerned or have experienced sensitivity or dry hair. These cleansers are perhaps not always as effective as SLS but they are available and may be gentler to your hair. If you have an SLS shampoo, you are using one of the most researched cleansers out there.


  • Makeup Theory says:

    I was going to write something very similar to AuNaturale’s post, but I think she said it perfectly. I’m not willing to take the chance either – just to save a few cents on shampoo.

  • Anonymous says:

    Now, I interpreted the overall message of JC’s post to be as follows (I’m paraphrasing): While you can make a personal choice not to use shampoos containing SLS, understand that SLS is an effective cleansing agent that is not as harmful as you think it is. I will probably get flamed for this, but I really don’t see how JC’s “supporting evidence” refutes the article’s premise that SLS can be harmful to the skin, at the very least, if not also the hair. I also don’t see how JC’s comments indicate that the article mentioned is “yet another example of a poor interpretation of science.” Maybe it’s just me, but I don’t think fact was separated from fiction here.

    From my understanding, this article was an interpretation of the Journal of the American College of Toxicology’s “Final Report on the Safety Assessment of Sodium Lauryl Sulfate.” Since JC alleges that the article is a misinterpretation of science, then let’s look at the ACT’s 1983 report (embedded as a link within the article), since that is the science, and compare it to JC’s analysis.

    JC found that there were no supporting articles, research, or evidence to confirm that SLS can mimic oestrogen in the body. Point taken. But what about the other points mentioned in the ACT report which indicated the harmful effects of SLS? JC said SLS is an irritant. The ACT report says the same thing, but the report goes into much more detail than that. Obviously, you don’t want shampoo in your eyes, but what about the potential health effects resulting from long-term skin absorption? The ACT report says the following:

    “Tests show permanent eye damage in young animals from skin contact in non eye areas. Studies at Georgia Medical College indicated Sodium Lauryl Sulfate kept young eyes from developing properly by possibly denaturing the proteins and not allowing for proper structural formation. This damage was permanent.

    Other studies have indicated that Sodium Lauryl Sulfate enters and maintains residual levels in the heart, the liver, the lungs and the brain from skin contact. This poses question of it being a serious potential health threat to its use in shampoos, cleansers, and tooth pastes.

    Still other research has indicated SLS may be damaging to the immune system, especially within the skin. Skin layers may separate and inflame due to its protein denaturing properties.”

    Is the ACT report incorrect on this point? Is this not a cause for concern?

    Next, JC said that SLS is not carcinogenic, but “has sometimes been found to be contaminated with a different carcinogenic chemical.” The ACT report basically says the same thing: “Carcinogenic nitrates can form in the manufacturing of Sodium Lauryl Sulfate or by its inter reaction with other nitrogen bearing ingredients within a formulation utilizing this ingredient.” I’ll take these to be facts. While I’m sure the presence of these carcinogenic nitrates is determined by other factors such as the concentration of SLS, to me, the fact that carcinogens can even be present at all indicates another potential harmful property of SLS. I mean, I’m no chemist, but from what I understand, carcinogens are not good for you. If I’m not mistaken, they are cancer-causing agents.

    Lastly, when it comes to SLS’s drying effect, JC said the following: “Yes some people find SLS to be drying, this is usually fixed by following up a shampoo with a conditioner so that you can correct the charge on the hair and help the cuticle to lie back down.” As I said before, I am not a chemist, so I won’t pretend to understand “charges” in the hair. But I do know that, as JC indicated, conditioners are designed to smooth down the hair cuticles after washing. I am also aware that not every single person experiences the drying effect of shampoos containing SLS. But I find it interesting that a good percentage of people do find that SLS shampoos are drying to their hair, including many of the women who have posted comments in this section thus far. So do conditioners really do a sufficient job of “correcting the charge” on the hair resulting from use of an SLS shampoo? I would say that’s a matter of debate. I don’t know about every one else, but I don’t know too many people who don’t condition their hair after washing it. In fact, I don’t know anyone who does that. Again, there are no absolutes, but I have a hard time believing that happens often. With that said, I would imagine that for those who’ve stopped using SLS shampoos, it’s because their hair still feels dry, even after using a conditioner—myself included.

    All in all, I’m not saying that JC is wrong, and I do give her a certain amount of deference because she is a chemist. However, in my opinion (and this may just be my over-analytical attorney mind kicking in), I don’t think she presented enough information here to refute the general premise of the article at issue or the evidence presented in the 1983 ACT report. I’m all about making an informed decision…so are there studies out there to refute that levels of SLS remains inside the body after being absorbed through the skin? If so, I’m all ears. If not, my mind is made up. While everyone is clearly free to “do them,” I am of the opinion that the warnings to stay away from SLS shampoos are warranted. To echo Dr. Darbre’s email to me, I think we should be concerned by the effect that the combinations of all these cheap chemicals have on our systems, especially since they are so easily absorbed through the skin. I’m just sayin…I need more info here.

  • Anonymous says:

    Great read! Thanks for breaking this down JC! Now I don’t have to hide my shampoos that contain SLS whenever my natural friends come around, LOL!

  • Natakue says:

    This was one of the things I’d ignored when I started following my modified curly girl routine years ago. Some shampoos are just more stripping than others so I don’t use them. But, no matter which one I choose, I ALWAYS have to follow up with conditioner.

    Thanks for providing another side to the story, JC.

  • Candice says:

    Thank you so much for shedding light on this. Great read!

    aka Mochakiss82 at

  • Claudia says:

    Nice to know that SLS is not the DeathChemical that some sites and bloggers claim it to be.

    I have always used SLS shampoo’s, some drying, some not at all. I stick with what works and leave SLS off my black list.

  • Anonymous says:

    A lot of these “don’t use” substances that people say about natural hair is ridiculous. As a chemist who works with a plethora of chemicals daily, people would be surprised to know which ones really aren’t problematic.

    Then you have people who jump on the wagon when someone says what’s good and what’s not good. People, in the end, you need to do your own research and stop relying on the intelligence of others, for you have your own brain for a reason.

  • Laquita says:

    Great post :o)

  • Wes says:

    Great post… I too am learning that most of the ingredients we try HARD to avoid aren’t really as bad as we think. This saves me money b/c I don’t have to spend an arm and a leg on what’s considered the “good” stuff.

  • Anonymous says:

    I do feel that some of those claims are a bit extreme and thank you JC for doing such great research for us. However, SLS (lauryl and laureth) are extremely drying to my hair. I chose to become natural almost 10 years ago because I was working out daily and sweating profusely including my hair, so I just chopped off the perm so I can wash my hair daily. Well my hair eventually got soooo stripped so without any scientific research, I know that SLS wrecked havoc on my hair. I have also found that Giovanni shampoos which have olefin sulfonate to be drying whereas Ojon Hydrating Shampoo with magnesium laureth sulfate to be much less drying. JC, how is olefin sulfonate and magnesium laureth sulfate different from SLS? I would really appreciate a response.

  • Anonymous says:

    WOW! Thanks Nik for finding the article & thank u JC for informing us of the truth! :o)

    That was a great READ.


  • Lteefaw says:

    Perfect example of why you can’t believe everything you read,especially on the internet. It’s a good thing JC was able to review that article and separate fact from ficition.

    I myself prefer not to use shampoo that contains SLS. I’ve found that it leaves my hair awfully dry. Since I use mostly natural porducts on my hair there really is no need to use harm chemical fulled shampoos.

    During the winter when I can only wash my hair once a week I simply scrub my scalp with a mixture of Sugar in the Raw and olive oil follow by a co-wash. And from time to time I use Deva Care No Poo.

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