7 ingredients to avoid in shampoo and other hair care cosmetics

A shampoo has a hard-to-read list of ingredients with complicated names. The list is so long that usually we don't even bother to look into it. I think we should. Just to check if such a commonly used product contains chemicals that are not only bad for our hair, but also dangerous for health. Here is a list of chemicals to avoid in shampoo and other hair care cosmetics that might irritate your skin, damage your hair and even endanger your health.

1. Sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES)

Why they are used: To make rich and think foam and help thoroughly clean your skin and hair

Why they are bad: SLS and SLES are harsh chemicals that dehydrate the skin and can cause irritation 4, 12, 17. Besides, sodium laureth sulfate (SLES) might contain traces of carcinogenic chemicals – 1,4-dioxane and ethylene oxide 1, 7, 9, 23, 24. Even though all producers are required to eliminate these impurities, some amount of them can still be present in your shampoo.

Read more about SLS and SLES in the article: Why you should avoid SLS and SLES in your cosmetics

sles, shampoo, sodium laureth sulfate

2. PEG-containing chemicals

Why it is used: To improve the cleansing properties of a shampoo and moisturize our skin and hair.

Why it is bad: PEG is toxic if applied on the damaged or burnt skin. In addition, similarly to SLES, it often has traces of 1,4-dioxane, ethylene oxide and heavy metals (lead, nickel, arsenic, etc.) 8.

peg, shampoo

3. Propylene glycol (PPG-)

Why it is used: To prevent the freezing of shampoo during transportation. It has also been used to treat dandruff 3.

Why it is bad: Propylene glycol can cause skin allergies 11, 25, 26. Besides, it is toxic for infants, patients with heavy burns, renal or hepatic insufficiency and epilepsy13.

Back in 2002, there was a case of serious poisoning by propylene glycol: a two-year old child chew some cleansing towels and was found by his parents feverish, lethargic and heavily breathing 5. Even though the child has fully recovered, this story shows that propylene glycol is not as safe as was assumed.

By the way, propylene glycol as a component of ear drops was shown to cause irreversible deafness 15, 16.

propylene glycol, shampoo

4. Parabens

Why they are used: To preserve cosmetics

Why they are used: Similarly to siloxanes, parabens are suspected to disturb the hormonal system. If this is true, they can be involved in the development of cancer. Even though, these components are not yet proven to be carcinogens, intact parabens were actually found in breast cancer tumors 27.

Read more about these chemicals in the article: Parabens in cosmetics: a risk to our health?

parabens, shampoo

5. Diethanolamine (DEA), triethanolamine (TEA), monoethanolamine (MEA) and the derivatives

Why they are used: To maintain the desirable consistency of a shampoo or a cream.

Why they are bad: These components are irritating to our skin and eyes, with MEA being the worst irritant, followed by DEA and TEA 10.

Furthermore, these chemicals may react with nitrites (also commonly found in cosmetics) forming N-nitroso compounds - extremely aggressive carcinogens causing stomach, liver, and bladder cancers 18, 19, 22.

Another danger is that DEA might affect the development of fetus 2. So if you are pregnant or about to be, watch out for this chemical in your cosmetics.

triethanolamine, shampoo

6. Dimethicone, cyclomethicone (ingredients ending with -methicone or -siloxanes)

Why they are used: To maintain the desirable consistency of a shampoo, help the spreading of a cosmetic product and moisturize the skin (which is, in fact, a matter of dispute now).

Why they are bad: Cyclomethicone is suspected to disrupt the hormonal balance of our body by mimicking the female hormone estrogen 6, 14, 20. In addition, this chemical can affect the fertility 21. There are also some environmental concerns, because dimethicone and other siloxanes are not biodegradable and harmful to aquatic life 21.

dimethicone, shampoo

7. Petrolatum (petroleum jelly) & Mineral oil

Why they are used: To make your hair shine.

Why they are used: Petrolatum and mineral oil are derivatives of crude oil (petroleum) fueling our cars. These chemicals are cheap, so there is no wonder why many cosmetic manufacturers choose them over vegetable oils. Unfortunately, what is cheap, is not always good. For example, petrolatum can often contain polycyclic aromatic hydrocarbons (PAHs) strongly associated with cancer 28, 29. Besides, any potential benefits of petrolatum and mineral oil for our hair are now being contested 30.

mineral oil, shampoo

And to conclude...

Can the harm of these chemicals be exaggerated? Possibly. However, I would still encourage you to avoid components whose safety is not studied well enough or being questioned. We do use shampoo a lot, sometimes daily, and I think it is enough as a reason to choose it carefully. No need to remember long names of these chemicals by heart, just use the image below to navigate through numerous cosmetic brands. Wish you a lovely shopping!

dangerous chemicals, shampoo
Ingredients to avoid in shampoo and other hair cosmetics


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Love, love, love this article.  It's the best, most concise, easily understood article I've seen on this topic.  

Natalia's picture

Thanks! Happy to hear that the article is useful  Smile