What causes a shampoo to be harsh?

This post is courtesy of an email from Evelyn and she asks

Q: Does pH balance lessen the harshness of a hair product?

A: By pH balance I assume you mean lowering the pH of the shampoo. The reason why shampoos can be harsh is actually not related to pH. In fact many of the surfactants used in clarifying shampoos (for example SLES, ALES etc) actually have a natural pH of between 5 and 5.5 which is quite similar to the pH of skin and hair.

The reason why some shampoos are harsh is because the surfactant used is very effective at stripping oil (remembering that the purpose of shampoo is to dissolve oil). These type of surfactants have two key properties
1. They are very small in size
2. They have a negative charge

As an example: 

SLS (used in clarifying shampoos - regarded as harsh) Cocamidopropyl betaine (used in SLS free shampoos - regarded as gentle)

Length - short -12 carbon atoms

Length - longer - 19 carbon atoms

Charge - Strong Negative

Charge - Medium to weak Negative

Q: What can we use at home to adjust the ph of shampoo, aloe vera? 

A: You can add aloe vera to reduce pH and some naturals also add oils which reduces the ability of the shampoo to remove oil and therefore makes it feel gentler. 

I however do not recommend either of these methods because there is a fine line between getting your shampoo to be more gentle and changing it to become completely ineffective for cleansing. I recommend that if you find your shampoo to be harsh, try a different one instead. I also think that sometimes products with a high pH  such as shampoo bars and castile soap actually feel quite gentle because often some oil and glycerin is left in or added during the manufacturing process.


  1. that´s quite interesting. Thank u again Jc! You are doing a wonderful job!
    Right now i am searching for a supercleaning shampoo!

    1. You are welcome. A clarifying shampoo is good for removing buiild up or excess oil. Be careful with using them regularly because if you do not naturally have oily skin and you wash your hair frequently, they can cause irritation (redness, itching of the skin=

  2. Jc, I have always loved your blog, but I disagree with your assertions about pH balance. I agree with this quote: "Most shampoos are alkaline, and this alkalinity can swell the hair shaft and render it more susceptible to damage. This is not a problem for patients with healthy, nonporous hair containing an intact cuticle. Patients who have damaged or chemically treated hair with a fragmented cuticle may wish to avoid hair swelling by selecting a shampoo that has an acid added to balance the pH." I found that here... http://emedicine.medscape.com/article/1067572-overview#aw2aab6b5. And I've seen the same reasoning in other references. I believe our hair has a "naturally compromised" cuticle layer. Honestly, I don't think saying it is "fragmented" would be a stretch either. If pH balanced shampoo eases the journey, I'm all for it!

    1. Hi Nicole - I am happy for you to disagree. I think that the statement you quoted is wrong. Many modern shampoos will have a pH which is between 5 and 7. I have personally tested 2 from herbal essences and one from pantene. These were ph6 to 6.5. I honestly have half a mind to request shampoo samples from various companies and do a large scale pH testing regime.

      As I stated here, synthesised surfactants (sls, als, sles ales) tend to be made up to a naturally low pH.The reason why they were developed in the first place was to replace alkaline soap so it would not make sense for them to be alkaline.

      Alkaline shampoos tend to be soap based and yet many consumers will not have bad experinces with them. Even people who use baking soda do feel that it is not harsh. I would cite Roshini of glamazini as a long time user of castile soap and Sera of sera252/2544 as a baking soda user. Both have gorgeous hair. I choose to use shampoo but I do not see valid grounds to demonise those who select an alkaline product.

      Hair naturally resists changes to pH and does it quite well between pH 4 and 9. Hair density (which is a measure of volume/expansion) does not change by any significant means in this range. I challenge you to read this particular research paper on the subject and I will debate you on the facts contained in it. ( http://journal.scconline.org/pdf/cc1981/cc032n07/p00393-p00405.pdf)

      All you need to convince me to adjust my position is a research paper that shows natural untreated hair is damaged in th pH 4-9 region. I am more than happy to read and cite actual research papers

  3. I'm not trying to demonize those who choose alkaline products.

    I want people to have an enjoyable, easy as possible natural hair journey. I believe Dr. Draelos (the author of that quote) meant most shampoo *detergents* are alkaline. Which I think you would agree with. The section of the article I quoted is titled "pH adjusters". As you know, citric acid is often used to adjust the pH of the detergent mixture down from the 9-10 range to the 4.5-6.5 range. I agree with you that most (finished) shampoos are pH balanced. BTW, some of the "natural shampoos" are not pH balanced which is why I think this topic is so important.

    Regarding hair and pH, I agree that keratin protein naturally resists pH changes. My assertions are related to the shampoo process.

    Two facts that accept your statement regarding the pH 4-9 region, but still remain true:

    1) Washing is done by saturating the hair in water and subjecting it to significant friction.

    2) Hair with a compromised cuticle layer will experience more damage in that scenario than hair with fully intact cuticles.

    I'm not talking about keratin proteins and hydrogen ions; I'm talking about the logistics of hair care. I think that distinction is at the heart of most topics on which we might disagree.

    Regarding Roshini and Sera, I believe that they would still benefit from finding the right pH-balanced shampoo to meet their needs (Pantene and HE are fine choices) and I think no matter how gorgeous the hair, people always appreciate suggestions that will make their routine easier or faster.

    1. We have to agree to disagree. I maintain that the statement used in the article is wrong. I also do not believe that the cuticle of African hair is compromised, I have seen high resolution micrographs that show no difference between Caucasian and African hair cuticles (number, stacking, direction of lay, appearance).

      I think that people like Roshini and Sera are valuable. They demonstrate that alkaline products are not necessarily responsible for damage or breakage. This is an important messsage because in my view switching to a 'ph balanced' shampoo will never ever sort out issues of breakage and damage. These issues have a mechanical cause and the resolution is also mechanical.

      As always I am happy to read and report back on journal articles that counter the research that I have reported on so far.

  4. This is really good information, Jc.

    I stopped using baking soda merely because the pH was 9. In all honesty, though, my hair didn't feel damaged from the use. I just assumed anything above pH 7 was bad for the hair given a youtuber's video. This post you've done is well-researched and has made me reconsider how I look at shampoos.

    1. Thanks Loo. I am a huge fan of your gorgeous hair!

    2. I wont't buy again Trader Joe's Nourish Spa (left my hair stripped).
      I use Indian Aztec Clay for fun when I'm playing with my hair.
      My newest find Is Kinky Curly Come Clean shampoo. Left my hair soft but clean and it says Ph balanced on the bottle.

  5. Jc,

    The cuticle of African hair may be intact when it first emerges from the follicle, but it just takes a few weeks of mechanical damage to put our hair in the category of "compromised" cuticle or porous. Think in realistic terms about the vulnerability of our hair and the vigor of our styling efforts.

    There's an SEM image in this article of a "typical" African hair: http://www.happi.com/articles/2010/04/effective-treatment-for-ethnic-hair. Peer-reviewed journal articles are quoted at the bottom in the References section. The strand in the micrograph may have had the same # of cuticles as Caucasian hair before it was ever combed or brushed or blow dried, but a typical head of African hair has been through those things multiple times. Even children's hair has accumulated significant mechanical damage by the time it's 1 year old.

    I also found AFM images on pg 29 of this thesis http://www.mecheng.osu.edu/nlbb/files/nlbb/Seshadri_Thesis.pdf.

    A pH balanced shampoo helps the cuticle resist swelling which means less damage will occur during the subsequent styling session. Of course the practices leading to mechanical damage have to be addressed, but that doesn't mean other ways to mitigate damage should be ignored. The goal of most curly and kinky haired ladies is length because it brings so many more styling options. I'm just trying to help them get there. This is your blog, so whether you accept that or not, I will let it be.

  6. I did not arrive at my conclusion from a single source. I looked at a selection. Some of the key ones are:

    1. African hair cuticle at a kink (torsion twist) pg 31 of the pdf or pg 11 of the actual document Aachen Thesis
    2. High resolution image of African hair (natural) pg 125 of the pdf or pg 97 of the actual document QUT Thesis
    3. Nonhlanhla Khumalo's work - SEM images of the normal shaft, at knots, at areas of fibrillation (J Am Acad Dermatol 2000;43:814-20)
    4. The only paper (to the best of my knowledge) that details the cuticle structure of African hair (with high resoultion TEM staining) is this piece again by Nonhlanla Khumalo (Experimental Dermatology 2005: 14: 311–314)

    In all these pieces African hair has a normal appearance where it is not damaged (i.e not at knots or where a relaxer/hard brushing has been applied). Smooth flat cuticle just like Asian or Caucasian hair. At knots or flaws (mid shaft splits), the cuticle shows signs of damage.

    I do think that pH is a red herring. This is because the key reason why African hair breaks is not because the cuticle is raised. It breaks because of force applied during manipulated. African hair does have properties that cause it to break especially if you use tools/techniques meant for straight hair. For example due to the curl of African hair, it is more likely to form mid shaft splits. Due to the curl of African hair, it is likely to form complex knots when handled.These properties cannot be changed by any product but handling and style can have a major impact.

    The key to gaining length does not lie in pH balanced products. In fact some pH balanced products can feel very harsh - for example an sls clarifying shampoo at pH 5.5 can feel very harsh. We need to learn more about product ingredients and trust that if our scalps complain. we need to find something else even if it says pH balanced or all natural on the bottle.

  7. I agree wholeheartedly with your last paragraph. I have never said pH balance is the total solution for our hair. It's clearly not. We both agree that most shampoos are pH balanced and that the types of surfactants in the shampoo are critical. I think those facts alone are enough to discourage the use of baking soda and castile or black soap.

    I'd like to move the collective conversation forward and start talking about more beneficial surfactants (DLS for example), but it's hard because most people don't have a science background and when they try to accept science they see scientists equivocate about basic things. The online community has progressed very slowly over the years. It would be easy to find forum posts from 6-8 years ago asking if it's okay to use baking soda or castile soap to clarify. I'm saying No and moving on.

    1. I am saying that there is no right and wrong except for ripping your hair out. If someone finds baking soda, castile soap or black soap less harsh than a commercial shampoo I will tell them to always listen to their hair.

  8. Hi! Just discovered your website! I studied biology in college so I greatly appreciate you using science to explain so many confusing ideas of caring for natural hair :)

    I know it's a bit late but I just wanted to ask if using aloe vera is effective or if it doesn't make any difference. I've been thinking about using it along with my leave-in conditioner and my oils...

  9. On BGLH's site she suggested a mixture of 50% shampoo and 50% conditioner to make your shampoo less harsh. Would you not suggest that either?

    1. I would never suggest mixing shampoo and conditioner. They have different charges and they behave very differently. I should do a post on this, can't believe I haven't already


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