The 6 Chemicals Hiding In Your Shampoo That Could Be Causing Hair Loss
Hair Loss
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The 6 Chemicals Hiding In Your Shampoo That Could Be Causing Hair Loss

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You’ve fixed your diet, managed your stress and stopped putting your hair up in tight hairstyles. And still find that your hair is falling at the same rate that it did and you have no idea what is causing it.

What could be the source of your hair loss could be right in front of you, hidden in plain sight; in the shampoo and conditioner that reside in your shower!

In this article, we will be talking about the 6 chemicals present in your shampoo and conditioner that could potentially be causing you to lose hair.

1. Sodium Lauryl Sulfate (SLS) and Laureth Sulfate

When you wash your hair, you probably expect your shampoo to produce a thick, bubbly lather. But did you know that the chemicals that help produce that lather could be causing you to lose hair?

Chemicals such as Sodium Lauryl Sulfate (SLS) and Laureth Sulfate are chemical foaming agents commonly found in mass market shampoos. Also known simply as sulfates, their role is to act as surfactants to help lower the surface tension between the shampoo and your hair. By doing so, it allows the active ingredients in your shampoo to clean the oil, dirt and dead skin from your scalp more effectively.

When used in small amounts, sulfates are safe to use and make the shampoo more effective at cleaning. However, shampoos that contain high concentrations of SLS and Laureth Sulfate could overly strip your hair of its natural proteins and oils.

As hair is made out of 91% of protein, when protein gets damaged or stripped, it leads to weaker hair. In a study done by the scientific journal Colloids and Surfaces, researchers found that when hair was immersed in a sulfate solution, it lost twice as much protein than when hair was immersed in water. This stripping of protein weakens your hair and can lead to an increase of splits ends and hair breakage.

So while Sodium Lauryl Sulfate and Laureth Sulfate are not directly linked to hair loss, if your shampoo contains high amounts of these sulfates, it can not only damage in the proteins in your hair which increases the likelihood of hair breakage but it can also irritate your skin, causing you to lose even more hair.

2. Sodium Chloride

You might vaguely remember sodium chloride from long forgotten science lessons, but did you know that sodium chloride - otherwise known as table salt - is present in mass market shampoos?

Used alongside ingredients such as Sodium Lauryl Sulfate (SLS), sodium chloride is often used to thicken products like shampoos and conditioners. While sodium chloride does not directly cause hair loss, should you use hair products that contain high concentrations of sodium chloride, it can cause your scalp to be dry and itchy which in turn could lead you to losing hair.

3. Parabens

Perhaps it’s never crossed your mind before but as you reconsider the bottles of shampoo and conditioner that live inside your bathroom, you might wonder if they ever actually expire.

Thanks to preservatives such as formaldehyde and parabens (propylparaben and methylparaben), shampoos and conditioners can last from 12 to 24 months once opened.

However the extended shelf life of shampoos does have its downsides, as the parabens mentioned could be indirectly causing you to lose hair. In a study conducted by the Journal of Applied Toxicology, it was found that parabens can induce allergic contact dermatitis and cause skin issues like irritation, itchiness and flaking to flare up; all of which can lead to you losing hair.

In a study done by the International Journal of Molecular Sciences, there was evidence to suggest that parabens could cause hormonal imbalances that not only encourage hair loss, but could also affect menstruation and pregnancy.

4. Diethanolamine (DEA) and Triethanolamine (TEA)

Similar to sulfates, Diethanolamine (DEA) and Triethanolamine (TEA) are synthetic ingredients that act as foaming agents and emulsifiers to help lower the surface tension between the oil-soluble ingredients and water-soluble ingredients so that they can blend more effectively together.

While DEA and TEA does not directly cause hair loss, it can damage your hair’s natural keratin and irritate your scalp, which in turn could cause you to lose hair.

5. Alcohol

Most if not all mass market hair products will contain some amount of alcohol in their formulation. However not all alcohols are created equally (or are necessarily terrible for your hair), for example fatty alcohols such as cetyl alcohol, cetearyl alcohol and stearyl alcohol to help soften your hair and help it retain more moisture.

Alcohols that you should avoid in your hair products are propanol and isopropyl alcohol which can dry out your hair and make it more prone to breakage. You should avoid hair products that has any of these alcohols listed as the first few ingredients, as ingredients are arranged by the highest concentration found in the product.

6. Propylene Glycol (PEG)

Similar to sodium chloride, propylene glycol (also known as polyoxyethylene or polyethylene) acts as a thickening agent in shampoos and conditioners. While propylene glycol does not directly cause hair loss, it can potentially strip your hair of moisture, leaving it brittle and prone to breakage.

If you are experiencing noticeable hair loss, it is advisable that you consult a doctor. Here at Zoey, doctors on our platform are best equipped with the knowledge to help ascertain the root cause of your hair loss. They will be able to advise you on the best treatment suited for you, and can also prescribe you the right medication should you need it.

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Written by our
Editorial Team
last updated
April 29, 2024

Articles featured on Zoey are for informational purposes only and should not be constituted as medical advice, diagnosis or treatment. If you have any medical questions or concerns, please talk to your healthcare provider. If you're looking for a healthcare provider, click here.


Engeli, Roger T et al. “Interference of Paraben Compounds with Estrogen Metabolism by Inhibition of 17β-Hydroxysteroid Dehydrogenases.” International journal of molecular sciences vol. 18,9 2007. 19 Sep. 2017, doi:10.3390/ijms18092007 (Link)

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