There’s a lot of talk in the beauty and personal care industry about sulfates. Not all sulfates are created equal, though. Some can cause irritation, while others may be safe to use depending on your hair and skin. So are sulfates bad for your hair? This article is here to help.
Sulfates show up in body wash, toothpaste, hand soap, laundry detergent, and a number of other personal care products. The trick is separating the good from the bad, knowing what to look for and what to avoid. We are obsessed with ingredients, so you can count on us to break it down.
Let’s get technical. We’re sharing the science behind two of the most common sulfates used in haircare: Sodium Lauryl Sulfate and Sodium Laureth Sulfate. We’ll focus on how they relate to haircare products, but these ingredients also appear across many other product categories.
Once you learn the difference, you’ll be able to better understand ingredient labels when you shop for hair products online + choose the right formula for your hair.
Key Takeaways
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Sodium Lauryl Sulfate [SLS] + Sodium Laureth Sulfate [SLES] are both surfactants used in haircare for cleansing and foaming.
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SLS is created first; it then undergoes ethoxylation to become the milder SLES.
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SLS is more irritating but carries no contamination risk, while gentler SLES can be exposed to the carcinogen 1,4-dioxane unless purified.
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Both can lead to increased sensitivity over time, so neither fully removes the risk of irritation.
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Every Living Proof shampoo is sulfate-free [no SLS or SLES] + color-safe, so you can choose by hair need rather than scanning the label.
Why are sulfates a concern?
If you’re new to the world of sulfates, you may be wondering why this ingredient gets flagged in the first place. As mentioned, sulfates appear in everything from cosmetics to dish soap + shower gel. They’re effective foaming agents, but they can also strip skin of its natural oils, which leads to irritation and dryness. When sulfates strip moisture from skin + hair, they can also cause scalp irritation. If you already experience dry scalp, you’ll want to avoid sulfates.
What is sodium laureth sulfate + what does it do to your hair?
Sodium Laureth Sulfate (SLES) is a surfactant, which simply means that this ingredient lowers the surface tension of water. Surfactants act as detergents because they are attracted to both water and oil. In shampoo, this is important because it allows the shampoo to penetrate deeper and thoroughly cleanse the hair.
What is sodium lauryl sulfate?
Sodium Lauryl Sulfate (SLS), also called Sodium Dodecyl Sulfate (SDS), is also a chemical ingredient commonly found in personal care products from shampoos to toothpaste. It, too, is a surfactant that acts as an effective cleansing and foaming agent, which is why it’s often used in haircare products.
So, what’s the difference?
The difference between sodium laureth sulfate and sodium lauryl sulfate
To avoid confusion, we’ll refer to Sodium Laureth Sulfate as SLES and Sodium Lauryl Sulfate as SLS. While they may sound extremely similar and are used in products for similar purposes, these ingredients differ on an important note.
Safety
You might have already figured out that SLES stems from SLS. SLS undergoes a process called ethoxylation to become SLES.
This process has two side effects:
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Reduces the harshness of the ingredient
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Exposes the ingredient to contamination
It’s a bit of a double-edged sword.
SLS can be quite irritating. However, the same process that makes SLES a less irritating ingredient than SLS exposes it to a known carcinogen, 1,4-dioxane. SLES must be purified through a vacuum stripping process to ensure it is free from 1,4-dioxane. However, there is no way of knowing if the ingredient has been purified or not. In most cases, products that contain SLES also contain 1,4-dioxane.
On the other hand, SLS is not at risk of contamination and hasn’t been found to contain 1,4-dioxane. The trade-off, though, is the risk of irritation. You can’t really escape the risk of skin irritation by opting for SLES. Although SLES is less-irritating, it too can lead to increased sensitivity over time. You may have experienced this. If you’ve been using the same toothpaste or shampoo for years and seem to all of a sudden react poorly (i.e. experience redness, itching, or uncomfortableness), you may have developed an allergic reaction.
Sodium laureth sulfate vs sodium lauryl sulfate in shampoo
Both SLS and SLES are commonly used in shampoo for their foaming properties that contribute to a robust lather and remove dirt and oils from the scalp. Formulas that contain SLS could irritate both a sensitive scalp and eyes, and formulas that contain SLES could be contaminated unless the company claims to have purified the chemical and ensures it is free from 1,4-dioxane.
While every shampoo needs a surfactant, you don’t have to rely on one of these ingredients to get the job done.
Formulas free from SLS and SLES
If you have sensitive skin or want to avoid potentially harsh ingredients, consider staying away from shampoos that contain SLS or SLES. In this case, it is best to look for a sodium lauryl sulfate or sodium laureth sulfate free shampoo. If you’re wondering what is sulfate free shampoo, it’s simply a shampoo that does not contain these potentially damaging sulfates.
Every Living Proof shampoo is sulfate-free [no SLS or SLES here] + formulated to be color-safe, so you can choose your formula based on what your hair needs, whether that’s smoothing frizz, repairing damage, or boosting volume, without scanning the ingredient label for red flags.
