20 Ingredients in Shampoo That Can Cause Hair Loss

Not all substances labeled "chemicals" are bad. Indeed, even elements like vitamins and amino acids your body needs have scary-sounding scientific names. It's not unusual for an all-natural product to have a list of ingredients that make your eyes roll back into your head.

That's not to say that chemicals are safe. Some do, indeed, cause damage, from skin irritation to cancer and everything in between. Many of the worst tend to be banned once their side effects are known, but others slip through the cracks.

Today, we're not talking about cancer, we're talking about hair loss. There are a lot of different chemicals, both organic and non-organic, in your average shampoo. Over the decades, a huge array of different formulas, additives, and additional effects have been tried with various formulations. Some of the chemicals involved have proven to have detrimental effects on the body. 

Now, you don't necessarily need to believe us. Use objective science, not a health blog, to help you determine the health effects of any substance. We recommend checking any chemical you're not sure about in the Skin Deep Database, a cosmetics database that maintains entries for a wide variety of different substances. Not only will it tell you the name, chemical formula, and usage for a chemical, it will inform you of any alternative names and health effects the chemical may have. You can also search for entire brands, if you don't want to check every ingredient individually.

When it comes to hair loss, obviously you want to avoid it as much as you can. And yet, many common ingredients in shampoos and conditioners can lead to hair loss, hair fragility, or scalp irritation. Here are 20 such ingredients.

Note: One common concern you'll see is that all of these chemicals are considered toxic. That's not necessarily a bad thing for shampoo; after all, you're not supposed to drink your shampoo. What you should be more concerned about is skin irritation and other topical concerns.

1. Sodium Lauryl Sulfate

Sodium Lauryl Sulfate, also known as SLS, is one of the most common ingredients in modern shampoos. It's mostly used because it reacts well with water and the oils in your hair, making it a good soap and cleansing agent. It also has emulsifying properties, which means your shampoo will foam nicely.

Unfortunately, the act of breaking down all the oils in your scalp and hair leads to thinner, dryer hair. Your hair needs a certain level of natural oil to remain healthy.

2. Sodium Chloride

Here's an example of common, every-day chemical with a scary name if you don't know what it is. Sodium Chloride is made up of sodium, which explodes in water, and chlorine, which is extremely dangerous. Combine the two, though, and you have this: simple table salt. You eat this every day.

Eating, however, is not the same as using in shampoo. As you may know, salt dries out its surroundings. It's used in shampoo as a thickener, but it can also dry out your scalp and make it harder to refresh and grow hair.

3. Polyethylene Glycol

This chemical, also known as PEG, is used in shampoo as a humectant; in other words, it helps retain moisture, preventing your shampoo from drying out. It's also a solvent and has soap-like properties for the oil in your scalp.

Much like SLS, PEG breaks down and strips oils from your hair, which your needs to remain robust and lively. It's toxic to the organs, as well, though again; you shouldn't be drinking your shampoo in the first place, so this shouldn't be a concern.

4. Quaternium-15

Quaternium-15 is possibly the most dangerous chemical on this list, and you should avoid it in any shampoo for more than just hair health reasons. It used to be used as a preservative, but also has antimicrobial properties.

Of course, the same action that kills microbes can damage your body. It has been found to be extremely hazardous as a chemical, with potential cancer-causing effects, as well as high risk of allergic reaction. It also releases formaldehyde, with its own detrimental effects.

5. Methylparaben

Methylparaben is one of the paraben family of chemicals, which you may have heard of before. Parabens are commonly used as preservatives in cosmetics, including shampoos. They have also been found to have potential endocrine side-effects, allergic reactions, and some potential concerns about interfering with gene expression. If you don't know what all of that means, it basically interferes with hormones in the body, which can have wide-reaching effects. 

6. Propylparaben

Propylparaben is another paraben, and is something like the larger, angrier cousin of methylparaben. It's a similar chemical used in a similar way, but has worse health effects. There's no cancer risk associated with it, but it can affect allergies and can have some toxic effects on reproduction. Overall it's classified as a moderate-to-high hazard chemical.

Parabens are pretty rare in modern, regulated shampoo, but if you buy your shampoo overseas or from an unregulated market, you might want to double-check that you aren't buying something that still uses parabens.

7. Diethanolamine

This chemical, also known as DEA, is found in small amounts as a diethanolamide. These are used in cosmetics and shampoos because they give the shampoo a creamy texture, and encourage foaming action. So much of what goes into shampoo ends up being about the appearance or feel of using it, not about the effect it has on your hair, which is unfortunate.

In any case, DEA is a known carcinogen and has a wide variety of skin irritation effects and other health effects. It's among the most dangerous chemicals on this list, so you should strive to avoid it.

8. Triethanolamine

Despite having a similar name and chemical composition as the previous entry on this list, this chemical – also known as TEOA or TELA – is a much safer chemical.



While it does have some negative side effects, it's primarily used to balance pH levels and as a cleanser to remove makeup. It's also used in some medications involving ear diseases. Nevertheless, it's not entirely safe for your hair. TEOA is a bit of an allergen and skin irritant, which damages the scalp and has long-term negative effects on your hair.

9. Phenoxyethanol

This is another chemical that is commonly used as a preservative in shampoo and other cosmetics. No one likes their shampoo expiring, right? Well, the downside to having so many preservatives in everything is that preservatives tend to be fairly bad for you. This one is no different. Phenoxyethanol is used as a preservative and as a fragrance, but it has a high risk of skin irritation, as well as eye and lung irritation. Since scalp irritation is one of the driving factors in hair loss other than genetics, you want to avoid it as much as you can.

10. Dimethicone

This chemical is also known by the longer and more complicated name polymethylsilxane, and it's a silicon-based polymer. The chemical is used as a lubricant and as a conditioning agent for your 2-in-1 shampoo and conditioners, and just conditioners in general. It's an anti-foaming agent and is meant to protect your hair. In other words, it's trying to replace the oils that your other ingredients are stripping. In addition to being a synthetic replacement for organic material, it's toxic if accidentally consumed.

11. Propylene Glycol

This is a very common ingredient in a lot of cosmetics and shampoos. It's an organic alcohol and is used as a skin conditioner, making it very common in lotions and skin creams.



In shampoo, it's also used as a replacement for the natural oils being stripped away. However, as an alcohol, it can dry out the skin and scalp, which leads to contact dermatitis, allergic reaction, and other irritations. This, as you may expect, damages the scalp and hurts your ability to regenerate hair.

12. Alcohol

Alcohols in general are typically bad for your body, inside and out. Even the ones we drink are poisonous. Some alcohols, the short-chain drying alcohols, are the alcohols that dry out your hair and skin. They irritate the skin and eyes, they dry out the scalp and hair, and they leave your hair brittle. They are most often found under names like SD Alcohol, denatured alcohol, propanol, and isopropyl alcohol. On the other hand, some alcohols are beneficial and not harmful, such as cetyl alcohol, stearyl alcohol, and behenyl alcohol.

13. Lanolin

Lanolin is an animal produce derived from the skin secretions of sheep. It doesn't harm the sheep to produce, and it's relatively safe, but it's still something you might consider avoiding.



In shampoo, it's used as a conditioner and emulsifying agent. As with many other chemicals on this list, it ends up stripping hair of the healthy oils it needs to stay strong and regenerate.

14. Petroleum

Petroleum is the same sort of chemical we use to make everything from Vaseline to gasoline. When found in something like shampoo, it's typically used as a replacement grease or oil, meant to restore a healthy-looking shine to hair. The problem, of course, is that this is taking the place of the natural oils your body produces. You're stripping them out and then replacing them with a poor, synthetic substitute, which prevents them from being restored naturally.

15. Mineral Oil

Mineral oil is an inorganic oil that serves much the same role as petroleum in a shampoo or hair conditioner. It's there to replace the oils that you strip out, and as we've mentioned repeatedly, stripping those oils damages hair. When you then try to replace those oils with inorganic substitutes, it might look healthier, but the shine quickly fades and the natural oils find it impossible to restore themselves.

16. Cocamidopropyl Betaine

This chemical is a relatively low hazard foaming agent that makes your shampoo foam up nicely in water, and it helps reduce static build-up in hair. It has cleansing and viscosity-increasing effects as well. 

The primary hazard for this chemical comes from being a skin irritant. It won't affect everyone, but some people have an allergic reaction to the chemical when it contacts their skin, including their scalp. You might not even notice it beyond a persistent itching, but that alone is enough to damage the scalp.

17. Triclosan

This is a moderate-level hazardous chemical that is used as a cleaning product and preservative. Because it has anti-microbial effects, it's found in shampoos and conditioners as a preservative and as a deodorant. 

The risk of triclosan comes from skin irritation and some potential hormonal toxicity. It's not dangerous in a small, one-time dose, but it can build up over time and as such isn't good for something you use regularly, like a shampoo.

18. Artificial Colors

Artificial colors run a wide range of different chemical compositions, and they usually are identified by a simple number, like Blue #3. These colors are unnecessary in shampoo, as they only serve to make it look better when you're buying or using it, and have no benefit for your hair. Some colors, however, can be irritants or allergens, and some people have dangerous levels of reactions to certain colors. Even minor irritants damage the scalp and can lead to hair loss.

19. Artificial Fragrances

Synthetic fragrances or perfumes are meant to make your shampoos more pleasant to use, and in large part the smell of a shampoo is one of the only defining traits it has.



However, much like colors, you don't need a fragrance in your shampoo for it to be effective. Rather, fragrances can be dangerous depending on the chemicals they use. It's generally best to avoid anything that lists fragrance as an ingredient, since they don't need to specify the chemicals that give it a particular scent.

20. Vitamin A

Vitamin A is typically seen as healthy for the hair, so why is it on this list? Like many nutrients, vitamin A is beneficial up to a point, and detrimental in overdose levels. Vitamin A is essential for growing and restoring healthy hair, but when consumed in too high levels, it starts to have the opposite effect. One shampoo with vitamin A is fine, but if you're also taking a supplement, using a vitamin A infused lotion, and using it in a conditioner, it may be too much.