Sunday, 10 April 2011

Ammonium Lauryl Sulfate and Sodium Lauryl Sulfate: Is One Better Than The Other In Your Shampoo?

Ammonium Lauryl Sulfate (ALS) and Sodium Lauryl Sulfate (SLS) are common primary or secondary detergents in commercial shampoo formulas. Should you be looking for one or the other in the shampoo you choose for your hair?

In terms of chemists working up a formula for a shampoo, the biggest difference between the two is how soluble they are in water. ALS is more than three times as soluble in water compared to SLS, which makes it an attractive ingredient for chemists to choose for use in clear or colourless products.

As to how they perform in your hair removing oil and dirt, they are identical. Both are recognised as being very effective detergents, particularly in lifting oily dirt.

Is either ingredient toxic? Both ALS and SLS share similar toxicity and pH profiles. So if you have an urge to drink your shampoo or rub it into your eyes, both ingredients will have the same effect. Basically, they will both taste awful, are very unlikely make you sick, and sting quite a bit if you get it in your eyes.

Does Sodium Lauryl Sulfate cause cancer? No, this is an urban myth. In 2000 a report on SLS from the Journal of the American College of Toxicology was  altered heavily to falsely imply that SLS caused cancer. This bogus report has since been widely copied and circulated on the internet.

This falsified report is still frequently cited by small, independent shampoo companies trying to promote sulfate-free shampoo as an antidote to female pattern hair loss, among other health issues. To date no connection has been demonstrated between the use of sulfates in commercially available shampoos and ill health or hair loss.

Shampoos that use ALS or SLS are completely safe for normal external use and are perfectly effective to use on all hair types. Provided the shampoo is rinsed thoroughly from the hair, there is no risk of irritation to even sensitive skin.


  1. Anonymous4/12/2011

    Cancer-NO Probably not, but sls is very drying to hair and skin. sls has corosive properties that over strip the oils from the hair. sls can even damage hair folicles in a newly shed hair. The damaged hair folicle leads to hair thinning.sls effective? Yes, it removes oil, but it removes too much. I quit using sls and sles, and have seen a dramatic improvement.
    sles(sodium laureth sulfate) is in question about causing more side effects since the chemicals used to lessen the harshness to the hair (sles is derived from sls) can enter the body through the pores. So although it is more gentle on the hair, it is worse for the skin.
    This gets rather complicated. I avoid sulfates now and my hair and skin shows it for the better.
    Do you have an article of the effects of sulfates and hair?

  2. Dear Anonymous,

    To completely ruin a great Mark Twain quote, there are lies, damned lies, and stuff repeated so often on the internet it gets adopted as gospel truth.

    Anonymous, I am really sorry, but you have been mislead. I am so glad you brought up all these brilliant points, but there are so many of them that are misleading at best and just false in fact, that I will respond properly to all of them but my first draft response was more like a book.

    I will deal quickly, though, with two of the more alarming claims, which are:

    1. The business about follicular damage by SLS. This is part of the original falsification in 2000 of the original paper written by the CIR in 1983, which I mentioned above. The CIR and the Journal of the American College of Toxicology have NEVER published a paper making this statement. They work even to this day trying to correct this (among others) completely baseless assertion.

    Here is the link to both their statement AS WELL AS their original paper:

    2. As to SLS being absorbed through our skin, SLS is a very widely used carrier in the pharmaceutical industry to aid absorption of drugs. The safety levels of SLS for this use is very heavily researched. Further, SLS biodegrades rapidly, 100% within 24 hours and is also easily metabolised and excreted by humans. This is also very well researched and documented.

    Thank you again for taking the time to respond as this is exactly the type of information I want to clear up for people.

    I also have a sneaking suspicion as to why you like your sulfate-free shampoo more than your original shampoo. It has probably nothing to do with sulfates and everything to do with concentrations.

    I assure you I will be posting more on this topic.

    Watch this space! :)

  3. Well, I’ve taken 5 tablespoons of Shikakai powder with 4 tablespoons of Lotus powder and mixed it with some water till it appears to be yoghurt like, left it over night and applied it the next morning on to the wet hair for about one hour.
    Afterwards I rinsed the hair out and felt that it really made a big difference, my hair felt so soft as if I had used conditioner and shampoo.

  4. Dear Anita,

    Thanks for commenting! And bringing up Shikakai powder.

    Shikakai powder (which you can buy on the internet!) is made from the bark, leaves and seedpods of the acacia concinna plant. Acacias are one of many, many plants that contain chemicals that are called saponins.

    Saponins characteristically have soap-like qualities when mixed with water, so have been used obviously by humans as a soap probably since prehistoric times ... until actual soap was discovered.

    What you probably didn't know is that saponins by and large aren't dangerous to humans. But they are very effective at poisoning fish, reptiles and some insects. These plants are traditionally also used by indigenous people not just as a shampoo, but for fishing. By poisoning the water.

    Another interesting fact about acacia concinna pod extract is that tested against other saponins (which are used in the formulation of vaccines as an adjuvant) is that some research suggests it is very effective in stimulating a strong immune response, but *only* when it is paired with the target antigen. It doesn't stimulate the immune system all by itself. And of course it has to be injected or taken orally in order to be absorbed.

    Acacia concinna extract has been flagged in the medical literature as something needing greater research in terms of toxicity. It is obviously poisonous in that it interferes with normal cell functions. We just don't know in what quantities.

    This doesn't have anything to do with using it as a shampoo, which is probably perfectly safe for you. It's just a cool fact.

    Oh, and Shikakai powder doesn't "nourish" the hair as is often claimed. It's just soapy.

    Now for the Lotus powder. Generally speaking we're talking about the powder of the rhizomes of nelumbo nucifera. Virtually this entire plant is edible and, importantly for this particular discussion, the root powder is used as a thickener, much as we use cornstarch or tapioca.

    Why this works well in the hair is because it sucks up water so effectively, thus giving you the *feeling* of hydration. This is a fairly superficial effect in the scheme of things because true hydration would be dealing with the cortex and not just the outside of your hair. But if you used it every time you washed your hair it would address any *feelings* of dryness.

    Of course if you shampoo (or Shikakai, if you like) your hair, you will still have to do something to rehydrate your hair as the entire way any detergent works is to make water essentially "sheet" away, lifting oil and dirt in the process.

    Again, there isn't any "nourishing" business going on.

    And it isn't a conditioner. Conditioners coat the hair to reduce friction between the individual strands, a very important part of protecting the health of your hair.

    Thanks again, Anita. This is all really good stuff!

  5. Whether it causes cancer or not it is still known to be a skin irritant and unnecessary harsh for daily/weekly use in hair or skin.


    1. Thanks for your comment! The classification as a "known irritant" comes from it's use in skin sensitivity research as a control substance, as the level of irritation when it is left (unrinsed, for a period of time from 20 minutes to a few days) from the skin is well documented. So all other chemicals used in skin sensitivity tests are scaled against this control patch.

      Shampoo is designed, of course, to be rinsed from the hair within a matter of minutes after application. It is also very dilute, and can be diluted further as it is readily soluble in water.

      Thanks for your comment as this is a common misbelief, widely spread on the internet.

  6. Anonymous4/30/2013

    Both Sodium Lauryl Sulfate (SLS) and its close relative Sodium Laureth Sulfate (SLES) are commonly used in many soaps, shampoos, detergents, toothpastes and other products that we expect to "foam up". Both chemicals are very effective foaming agents, chemically known as surfactants.

    SLS and SLES are esters of Sulphuric acid - SLS is also known as "Sulfuric acid monododecyl ester sodium salt", however there are over 150 different names by which it is known - see them here. In fact, SLES is commonly contaminated with dioxane, a known carcinogen.

    Although SLES is somewhat less irritating than Sodium Lauryl Sulfate, it cannot be metabolised by the liver and its effects are therefore much longer-lasting.

    A report published in the Journal of The American College of Toxicology in 1983 showed that concentrations as low as 0.5% could cause irritation and concentrations of 10-30% caused skin corrosion and severe irritation. National Institutes of Health "Household Products Directory" of chemical ingredients lists over 80 products that contain sodium lauryl sulfate. Some soaps have concentrations of up to 30%, which the ACT report called "highly irritating and dangerous".

    Shampoos are among the most frequently reported products to the FDA. Reports include eye irritation, scalp irritation, tangled hair, swelling of the hands, face and arms and split and fuzzy hair. The main cause of these problems is sodium lauryl sulfate. Yea I wouldn't be using stuff like this if you can avoid it. They are also showing in tests that both these surfactants can cause liver problems .

    As a soap, sodium lauryl sulfate is an emulsifying agent, which means that it has two distinct molecular regions. The tail, made up of carbon and hydrogen, sinks into fat, grease and oil. The head, composed of the sulfate group, doesn't sink into fat, because it's fat insoluble. Instead, the sulfate group is water soluble and stays outside the fat. Fat droplets become surrounded by soap molecules with tails in the fat and heads outside the fat, producing a unit called a micelle.

    Micelles, unlike fat droplets, can dissolve in water. Although fat is water insoluble, in a micelle, the fat is surrounded by water-soluble sulfate heads of soap-like sodium lauryl sulfate. As such, water and soap work together to surround fat, lift it from hair and clothing and wash it away. Micelle formation, explain Reginald Garrett, Ph.D., and Charles Grisham, Ph.D., in their book "Biochemistry," is favorable and happens easily.

    Sodium lauryl sulfate works well as a soap in soft water, but doesn't work well in hard water. Hard water contains calcium and magnesium salts, explain Garrett and Grisham, but soft water does not. The calcium and magnesium bond to lauryl sulfate, displacing sodium, and cause the soap to precipitate, or fall out of solution in solid form. When it precipitates, it can't form micelles, can't cause fat to dissolve in water and no longer acts as a detergent.

    Production of sodium lauryl sulfate requires the reaction of a chemical called lauryl alcohol with sulfuric acid, which is a source of sulfate. Lauryl alcohol comes from plants, including coconut, and is a derivative of chemical components of plant oils called fatty acids. Chemists can reduce fatty acids to produce alcohols like lauryl alcohol, explain Mary Campbell, Ph.D., and Shawn Farrell, Ph.D., in their book "Biochemistry," and lauryl alcohol can then be treated with sulfuric acid to produce soap.

    LIES...don't think so.

    1. Dear Anonymous,
      Thanks for your comments. Wow, a full on essay!

      As stated in my article above, the ACT report you reference never existed. You can contact the ACT directly if you wish to verify this, but they have an explicit report on their website stating that this report is completely false.

      You also seem to be confusing soap and detergent, which are recognised as two distinct classes of surfactants and not interchangeable.

      One interesting "cross breed" that has become popular very recently is the solid SLS "shampoo bar" however this is still a detergent and not a soap. The chemical processes involved in producing both are very different.

      Again, the ACT report you reference supporting your case is a falsification.

      Why shampoos use detergents rather that soap in their formulations are for a number of reasons, but an important one is that soap tends to have a pH that is not appropriate for hair, leaving it a bit "spongey" and not very nice to the touch.

      As pointed out by another commenter on my earlier "shampoo bar" post, using soap to wash your hair requires an "acid rinse" to optimise your hair's pH and give your hair a nice hard, smooth finish once dried.

      Or, you can just use a commercially available shampoo which will already have the optimal pH sorted out for you.

      Or not, if you prefer. If you've read any of my other articles about shampoo you'd know I do recommend people try a much reduced dollop of the stuff, but as in many things it is down to personal preference.

      It's great you've read a book on chemistry and I'm glad you have an interest in learning more about this area. There are a number of texts specifically aimed at hair care formulations which I'm sure you'd find interesting as well.

      Thanks again for your comment! It's all good.