Do You Really Need SLS-Free Shampoo?


Disclaimer:  You are about to read a shampoo article written by a bald man.  That doesn’t invalidate anything I have to day, I’m just letting you know in the name of full disclosure.  Heaven forbid someone gets upset in the comments section and lashes out saying, “What does he know.  He apparently hasn’t needed shampoo in years”.

On one of my daily internet information mining sessions I came across ads for SLS-free shampoo.  Now, anytime I read about “______ – free” anything it raises a big red skeptical flag.  Gluten-free comes immediately to mind.  Next comes fat-free, sugar-free, PABA-free and on and on ad infinitum.  Ironically, when a product has the word “free” in the title it usually costs more, as if the absence of something gives it a greater value.  We Americans are suckers for this kind of stuff.  Just for the record, you can buy gluten-free shampoo if you are so inclined.

Just what is SLS-free shampoo?  Well, SLS is short for sodium lauryl sulfate- an inexpensive chemical added to shampoos to generate huge amounts of bubbles and lots of lather.  It can also be found in carpet cleaners, engine degreasers and toilet bowel cleaners, among other household cleaning products.  This doesn’t necessarily mean it is intrinsically bad.  I mean, the sodium chloride I’m sprinkling on my yummy popcorn is chemically the same stuff that those big trucks spray all over icy roads here in the Northeast during the winter.

Technically, SLS is a surfactant; the chemical portion of the cleaner that sticks to the surface of the items and cleans it.  Each surfactant molecule has a hydrophilic (water-loving) head that is attracted to water molecules AND a hydrophobic (water-hating) tail that repels water and simultaneously attaches itself to oil and grease in dirt. These opposing forces loosen the dirt and suspend it in the water. The mechanical agitation of washing your hair helps pull the dirt free allowing you to rinse it down the drain.  As you might imagine, surfactants are an extremely important component of shampoos.  SLS is super cheap besides the fact that is an efficient surfactant.  That is why it has been added to shampoos for years and years.  Another reason SLS is so common in shampoos is what I like to call the lather factor.  It makes lots and lots of lather.  Advertising through the years has taught us that more lather is supposed to be a good thing.

Please allow me to digress for a paragraph or so to talk about the “no poo” movement.  It is thankfully not what first pops into one’s mind.  Well, my mind anyway.  What if we just didn’t use shampoo at all?  The “no poo” movement consists of people rejecting the societal norm of daily or almost daily shampoo use.  I suppose this makes me one of “them”.   Some fellow adherents of the movement use baking soda or vinegar to wash their hair.  Some use nothing but warm water.  The “no poo” crowd asserts that shampooing every day is a fairly modern convention.  Around the turn of the last century, shampoo was only used a few times a year.  After the Farrah Fawcett days of the 1970s, shampoo use really took off and now literally thousands of brands are available to the consumer.  Using shampoo on a daily basis removes sebum, the oil naturally produced by the scalp.  This causes the sebaceous glands to produce oil at a higher rate, to compensate for what is lost during shampooing.  According to some dermatologists, a gradual reduction in shampoo use will cause the sebum glands to excrete at a slower rate, resulting in less grease in the scalp.

Enough about the no-poo people, let’s assume you are the type who wants and needs a daily shampoo.  Are there any medical reasons not to use shampoos containing SLS?  Well…yes, if you are hypersensitive to it…but that is just common sense.  If you use the product as directed (lather, rinse, repeat) keep the stuff out of your eyes as much as possible, and don’t swallow it you should be just fine.  Back in the late ‘90s a rumor was going around the internet stating that SLS caused cancer.  This is just patently false.  Three different agencies, the Occupational Safety and Health Administration (OSHA), the National Toxicology Program (NTP) and the International Agency for Research on Cancer (IARC) have all stated that SLS is non-carcinogenic.  If you feel that you really need one more thing to worry about, consider MIT.  Methylisothiazolinone, or MIT, is an ingredient used in many commercial shampoos. MIT and its closely related analog, chloromethylisothiazolinone or CMIT, affect the ability of young or developing neurons to grow axons and dendrites in tissue culture.  Some studies have shown MIT to be allergenic and cytotoxic, and this has led to some concern over its use.

According to the experts at Melbourne Dermatology, …”SLS cleaners are safe and generally preferable to soaps… irrational and financially- motivated online scare mongering about this ingredient is rife.  The absence of SLS does not automatically indicate that one product is more suitable than another.”   As is the case with many subjects this writer looks at skeptically, there is some truth to the negative hype.  In this case it is the statement that using products containing SLS can be detrimental to the skin and hair.  This has nothing to do with the SLS itself, however.  The majority of cleansers containing SLS are a a poor match for skin, primarily due to their relatively high alkalinity and tendency to foam heavily.  Apparently lots of foamy bubbles may be appealing to the eye, but they do not aid in the cleaning process. A low or no-foaming method of cleansing the scalp improves the hair’s volume by desincrusting the follicles of the same sebum and dead cells commonplace shampoos help fix in place to produce long-lasting lift without the use of additional styling products.

What about the natural/organic angle?  Aren’t products without SLS “more natural” and therefore by the the law of faulty common sense, somehow better for you?  For that point of view you might want to look at  They go as far as to say that their shampoos are chemical free.  I have no idea how that is even remotely possible given the fact that everything that exists is composed of chemicals.  They state that “almost all shampoos contain harsh toxic chemicals that can damage your hair and weaken your health.”   As far as the argument that “natural = safe” goes, it is a faulty argument.  Raw cinnamon oil is natural  but I certainly wouldn’t want to put any in my hair for fear it would get in my eyes and blind me.

So, what is the bottom line here?  Do you really need to go SLS free or not?  If your current shampoo is causing irritation, you may want to consider using a product without SLS.  If the irritation is severe, you might want to consult your doctor about it.  You might just want to go SLS-free to try a shampoo with a different and possibly more efficient surfactant.  The point is that is it all your choice.  Just don’t let scare mongers make you feel like you have to go along with the latest fad in order to maintain your health.




The Ingredient Sodium Lauryl Sulfate Poses a Significant Risk To Shampoo Users,

Sodium Laureth Sulfate/Sulphate, Melbourne Dermatology

Cinnamon Oil is Dangerous, Gainsville Sun, 1985.

The Inconvenient Truth About SLS Free Shampoo, Top Article Source

Product Information,

SLS Free Shampoo, Squidoo

About Guy McCardle

Guy McCardle is an American science writer and skeptic. He is a certified Infection Prevention Specialist and served proudly as a Captain in the Army Medical Corps during Operation Iraqi Freedom. A devoted father and husband, he offers his unique viewpoints regarding science and the public interest.
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36 Responses to Do You Really Need SLS-Free Shampoo?

  1. Ryan Haupt says:

    I had a friend comment about using shampoo without SLS and she claimed it was because SLS is bad for the environment when washed down the drain. Did your research turn up anything about that?


  2. Guy McCardle says:

    Hi Ryan,

    I didn’t come across any environmental concerns when doing research for my article. That doesn’t mean it’s not out there somewhere though.

    The Inconvenient Truth

  3. Henk v says:

    Its a VERY good point to bring up…Does SLS or normal shampo contaminate the environment?

    It doesnt matter as these sorts of things contribute to sewage load. It doesnt matter what we pop down the will cause some environmental damage down the track.

    The fact that food waste and sewage is not reycled back to energy and biota in most western countries is something that has to be adressed.

    Some localities do recycle sewage for power. Some reseaech has been carried ot into getting weeds to grow on sewage farms to minimise the final environmental impact. Given that its only a chemical engineering problem to do both, most of us cant see why we dont.

    A desalinator can be run on sewage power and the sewage itself can be sterilised within such processes to form perfectly good fertiliser.

    Two good reasons to give your government a good nudge..

    Thanx for the article Guy and would you like me to be a transplant donor..I have lots of it on my head!

  4. Max says:

    “Ironically, when a product has the word ‘free’ in the title it usually costs more, as if the absence of something gives it a greater value.”

    Yeah, companies should charge extra for the lead in paint and gasoline. “Now with more lead!”

  5. J says:

    Interesting post. I’m a firm believer that SLS is what has caused my scalp eczema and exasberated my regular eczema. I’ve not used SLS on my hair for over a year, aside from a week’s holiday and a sample product, and both of these times I’ve felt as though my scalp was on fire, no exaggeration. I’ve switched to using SLS free bodywash and my skin is smoother and less irritated, and there is definitely a correlation. It’s stupid how companies like Head and Shoulders advertise that they’ll get rid of dandruff yet still use SLSs which research shows most likely causes the severity in some cases.

    As for thecost aspect, I think most companies just use SLSs in order to increase their profit margins and that they don’t care about what their customers are putting on to their bodies. Environmentally, I’m not too sure of the consequences.

  6. Maria says:

    I find it quite disturbing that you would lump in gluten-free with fat-free, sugar-free, and PABA-free. Three minutes of research would tell you for 5-10% of the population, the body reacts to gluten as a toxin, killing off the villi in the small intestines leading to malnutrition over time. It took my cousin 9 years to be properly diagnosed and nearly 4 years to heal. In Italy, newborns are tested for this at birth to prevent infant wasting due to the high levels of gluten in the average diet. Gluten-intolerance is an allergic reaction that is not quite as toxic but also causes long term damage all the organs of the body via the immune system reaction to the protein in wheat and related grains.
    Basic fact checking before assuming that everyone who buys gluten-free products is wasting their money on a diet ‘fad’ would be a lovely courtesy.
    As for your SLS info – I agree with much of your premise, however, I used to have scabs on my scalp. Now I use SLS-free shampoo and I don’t get scabs or dandruff or itching. It works for me and that’s really all that matters to me.

    • Josh DeWald says:

      No Skeptic is denying that gluten-intolerance (be it Crohn’s disease or otherwise) is a real problem that affects some people.

      But gluten-free labeling *is* a fad if you’re not actually sensitive to gluten. There are plenty of people allergic to wheat, peanuts, dairy, soy, egg protein, etc but those are often relegated to small print on the back of packaging, why should gluten get special prominence up front except that currently gluten-free diets are enjoying some popularity out of proportion to the actual number of people who have gluten intolerance.

      • Katie says:

        As someone with said allergy, I’m not claiming that it’s fair to all other allergies. The fact is, though, the majority of the population doesn’t deal with our issues and companies are trying to sell to the majority of people. The only way this stuff gets labeled is if either it becomes a fad or someone dies from it. However, whether or not it’s a fad, and whether or not it’s valid for the rest of you, I’m embarrassingly grateful for it. Gluten has an effect on my skin (dandruff, ecsema, breakouts,) and I’m glad that cosmetic companies label it. Thank God for fads.

  7. celeste says:

    personally I have been using baking soda instead of shampoo for almost a year now and I absolutely love it. My hair is incredibly soft and so much smoother and stronger than it used to be. I dont have ANY split or dead ends. I only shower about twice a week now and my hair and skin are healthier than ever.
    This method wastes less water, MUCH less plastic bottles, less energy, etc.
    I understand that that’s not really what your article is about but I just want you to know that people don’t just use alternative products like this because they are “___ free” many of them really are better for you.

    • Danielle says:

      I’ve been reading a lot about using baking soda, etc and would like to try it! Any tips to get started? ☺️

  8. Researchers at the University of Bath (UK) conducted research into Sodium Lauryl Sulphate and found that, when applied to the skin, it causes irritation and thinning of the protective barrier. Why, then, do the prescribed skincare lotions for these conditions contain just this very ingredient? Because it is a very good detergent and allows these products to be used as a soap alternative. Now that we know this, new products are being released without the SLS added.

    The fact of the matter is that something is only a fact until research proves otherwise. People have been using this for years thinking it safe as the scientific evidence of the time indicated it was. Now research has proven otherwise.

    How many other chemicals are we using every day that may one day be shown to be quite dangerous to our well-being?

    I believe it is no coincidence that the huge rise is eczema and dermatitis in our modern society correlates with the increasing use of chemicals in our foods and skincare products.

    • Why do you think there is a huge rise in dermatitis in our society? That seems quite extraordinary to me.

    • Cil says:

      SLS has a long carbon chain derived from fatty acids (so, derived of lipids) that is able to solubilize the “protective barrier”, which is a fancy name for lipids (or fats) in the skin. Now, our skin comes into contact with a lot of substances, many of them dangerous and able to penetrate this protective barrier and get access to our bloodstream. Some of these pollutants can get stuck in the skin for a while before they are absorbed. So, wouldn’t it be good to remove them?
      You can use one removal method for each substance you come across (cigar alone has around 4000 chemicals), but then you would have to spend a week doing so. Therefore, using SLS is the way to remove these stuck chemicals together with a little bit of the protective barrier, which will be replenished by our organism. I am trying to point out that the removal of a little bit of the protective barrier is necessary to keep our skin safe.
      It all comes down to the amount of the substances containing SLS used in any product and how the person uses the said product. Sleeping pills are supposed to help people sleep, but some of them use them to kill themselves. CO2 is the gas used by plants so that they can produce their own food, but if in higher amount it causes the well know green house effect.
      It is a five by five situation.

  9. Sabrina W. says:

    I wanted to know know about the SLS debate and actually was HURT by your claim of “gluten-free” fad. Having gone to doctors repeatedly from 1999-2002 with a list of valid symptom (swollen glands, headaches, sore throats, etc.) and told just to take this or that without any relief was difficult. After switching doctors and getting a blood test to find my symptoms were due to gluten allergy, then changing my diet and finding relief is not a fad! The previous doctors actually put in my chart, “She will often complain about the following:…”

    This may seem like a fad but some of us really have suffered…For me, I was alone. At the time, no one had ever heard of a wheat allergy.

    I stopped using SLS products in my hair but last night used a product that contained it. I noticed there was a deep cleaning along my scalp but my hair felt wire/straw-like. I may just try the baking soda to get the deep cleansing I am looking for.

    Hopefully, we will gain a better understanding of the effects of this chemical as well as many others.

    • Jess says:

      I agree with Sabrina. I was slightly offended by the whole ‘gluten free fad’. I went back and forward to the doctors for about 4 years with horrible symptoms. A lot of the time they thought I was just moaning until one doctor tested me for coeliac’s disease. I then had a biopsy which confirmed I had coeliacs disease, without this ‘fad’ of labelling gluten free products I could potentially be putting my body at risk still. Like any disease or intolerance/allergy it can become a life threatening problem.

  10. Anonymous says:

    As a bald man, you may be missing a critical angle of the SLS debate…the health of the hair. SLS can be very drying to the hair when used daily,, resulting in split ends and broken strands.

  11. Jezka says:

    Actually many people avoid SLS for the simple fact that it is used by scientists to destroy the protective layer if the skin; which is why when you wash your hands frequently your skin gets severely dry cracked!

  12. Anthony says:

    Dude, SLS-free shampoo is better for your hair. You’re bald, so I don’t expect you to know. Often times, what costs more is usually better. I’ve been using shampoo with SLS for years and it leaves your hair dry, prone to breakage, and brittle.

  13. rena says:

    I am 34 and have fought acne since my early 20’s when most people were clearing up I had flare ups that were ridiculous. No amount of topical acne med or prescribed pills seem to help, really they did more damage then anything. I came across the SLS issue recently and thought…why not, maybe I’m having a reaction. So, I went SLS free…shampoo, toothpaste, body wash…anything that touched my skin…2 weeks, absolutely clear skin! I’m not saying that it is a factor in all adult acne cases by any means..but for me, with no other changes made I am sticking with my new SLS free way of life.

  14. Vioke Violet says:

    i actually use shielo’s hydrate line of shampoos (which are sulfate free) to wash my hair. It doesnt have any of those harmful ingredients. I used to have the worst hair, and now I ALWAYS get complements when using the shielo shampoo. Worth the price. . .

  15. Anonymous says:

    I think the larger issue here is that SLS is not carcinogenic on its own, but when it bonds to other chemicals it forms nitrates which are carcinogenic. That couldn’t be a problem I suppose if we didn’t absorb hundreds of other random unlisted chemicals hidden under their names Fragrance, perfume, and parfum. No to mention the fact that most SLS free shampoos are also paraben free. Parabens are strongly related to hormones disruption and breast cancer.

  16. M. says:

    I used to have very smooth skin, but when I started using a shampoo that had SLS, I started getting pimples on my forehead. And they’re most prominent just after the shower. I don’t think it’s a coincidence. Definitly getting an SLS free shampoo.

  17. Anonymous says:

    if you cant eat it,dont use it

  18. Dr. Snuffloctopus says:

    I’ll chime in for one reason. I’ve been doing the no-poo crap for a while now, and it’s not for the environment, it’s not cause I’m allergic to SLS, and it’s not because “If you can’t eat it you shouldn’t use it” concerns me as many blogs claimed when I was looking for info on it. I’ve been using a mix of 1 tablespoon baking soda to 1 cup water in my hair. Since then, my hair doesn’t get oily as fast. Serious. That’s really all there is to it. (Even on hot days where hair is usually grody after, my hair doesn’t LOOK like it needs a washing.) I also use the mixture to wash my face (as face wash also has SLS) and have found that my face also refrains from oil-pitting it up. I’m the type who produces a lot of oil naturally, and SLS really does cause, at least for me, your pores to go into ridiculous overdrive. (Not to mention a box of baking soda is a friggen buck, and makes a LOT of “shampoo” Less oily hair, more money? I’m down.) (And just to note, my hair has no scent. It doesn’t smell good, but it doesn’t smell bad. It’s definitely had less build up (which, with the pixie cut I got recently, has left it sorta sticking up everywhere cause it’s all light and fluffy.) but I can’t really say anything about split ends, because I have thick hair which has always stood up to the apparent “damage” SLS causes.)

    tl;dr, I use baking soda and water cause it costs less and my hair no longer looks like it hasn’t been washed for 3 days after 16 hours. Not because I’m an ultra “conserve the land with organic veganism” person who thinks SLS will give me cancer or mug me or something.

  19. Loi says:

    From what I know of SLS , wasn’t it first used to break down skin so other things could be absorbed easier? If its made to break skin down then maybe it shouldn’t be used on skin! Also it is derived from coconuts so if you are allergic to something and it has SLS in it, check at your doctor for a coconut allergy! I was having skin peel inside my mouth because of SLS in my toothpaste. Later finding out it was also in my dish soap, shampoo , laundry soap and even my cream that my dermatologists gave me! I had suffered for YEARS before linking it all to coconuts! Removed coconuts, coconut oil and water and all SLS containing products! Now I have a life!

  20. C DVS says:

    I think the main reason to avoid SLS is because it unnecessarily strips your hair and scalp of natural oils. This causes your skin to secrete MORE oils (because it doesn’t LIKE to be dry), making you think that you have to shampoo again and again. If you stop using SLS, your scalp will stop producing so much oil and then you can move to the next step – shampooing LESS. I have washed my hair with conditioner now for over a year, using an SLS-free shampoo maybe once a month. My hair is quite noticeably more healthy and less prone to frizz. I attribute this to the fact that my hair is able to retain more moisture.

  21. Anonymous says:

    everyone is so worried about the shampoo they use and the products that have parabens. I just looked on a package of cookies my daughter and I had from
    peppridge farm and it actually contains sodium lauryl sulfate.

  22. The other reason not to use SLS is that it is a very powerful surfactant, if your hair is prone to dryness using such a powerful degreaser may not be the best for it. I use Johnson and Johnson baby shampoo (when I do shampoo, mostly I wash with conditioner, which also contains surfactants, but in lower concentrations) because I have very long hair and the ends get very dry.

    If you’re prone to greasiness however, SLS is fabulous.

  23. MJ says:

    I must be extremely sensitive to SLS. If I use toothpaste with it, I get mouth ulcers and my tongue swells. If I use shampoo with SLS, my scalp is irritated. If I dry my hands on a towel washed in SLS detergent, the palms of my hands peels, cracks and bleeds. It is more difficult to find SLS free products but for me, it’s a quality of life issue!

    • Beverley Murphy says:

      My daughter has had excema for a number of years and we have only been able to treat her problem with cortisone. Many of the other products on the market which claim to ease excema symptoms actually include SLS but having switched to SLS free products there has been a defining difference in her skin. It has taken 8 months to see a vast change in her condition but it has been worth it. I agree with the comments of do whatever works for you but if you have excema please try using SLS free products they won’t harm you but they could actually clear up your condition.

      • You really cannot recommend eczema treatments based on personal experience Humans are pathologically wrong at figuring things out by self experimentation. That is why medical treatment was mostly lethal prior to the experimental method.

  24. Kaur says:

    Do any of you know any social impacts of SLS?

  25. Hair Recipes says:

    I understand your point Guy, I have been using natural hair products for years since I have had huge problems with “mass market” products. People who think that paraben, SLS… don’t do anything are wrong. Actually, these persons may have no problem with these components, but they are a big deal for a lot of people, this is no surprise that new shampoos are developed to address the problem.

  26. Dave says:

    I have been struggling with this for four years now and still cannot get the little blisters out of my skin in a couple of spots mow I use all SLS free products. Thank god for Netrogena SLS free products and yes toothpaste and almost all handsoap get me started all over again. Stop washing your hands in public. Someone should invent a safer product.

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