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Reviewed by Katelyn Hagerty, FNP
Written by Our Editorial Team
Ever wondered why shampoo quickly turns into foam when mixed with water? The answer, for many supermarket shampoos, is the inclusion of chemical foaming agents like sodium lauryl sulfate and sodium laureth sulfate.
Known commonly as sulfates, these ingredients help shampoo mix into water, creating the foamy texture — the lather — you get when you massage shampoo into your hair and scalp. Sulfates are commonly found in mass-market shampoos, including most of the brands you’ll find in your local supermarket.
At low concentrations, sulfates are considered safe to use. However, frequent use of products with a high concentration of sulfates may lead to buildup, which can contribute to cell damage and excess stripping away of natural oils and hair proteins.
From a hair care perspective, this definitely isn’t a good thing. In this guide, we’ll look at how the most commonly used shampoo sulfates can affect your hair, as well as the key reasons why you should avoid shampoos that contain chemical sulfates.
From a chemical perspective, sulfates are surfactants. Their job is to reduce the level of surface tension between your shampoo and your skin, allowing the active ingredients in the shampoo to do a more effective job of cleaning dirt, oil and dead skin from your scalp and hair.
A variety of products contain sulfates, from shampoo to liquid dish soap and laundry detergent. When used in shampoo, ingredients like sodium lauryl sulfate and ammonium laureth sulfate amplify the shampoo's effects, allowing it to strip away more of the things that make your hair oily and uncomfortable.
Sulfates are “good” in the sense that they make shampoo far more effective. But they’re bad in the sense that they can have too much of a cleansing effect on your scalp and hair, resulting in excess stripping away of naturally occurring proteins and oils.
There have also been rumors over the years that sulfates (including sodium lauryl sulfate, the most common sulfate in hair products) can potentially cause cancer.
Luckily, these rumors aren’t backed up by any scientific evidence. The sulfates used in shampoo and other hair care products are not known carcinogens, and there are currently no scientific studies that show any link between sulfates and cancer.
Still, sulfates can potentially cause damage to your hair when overused, ranging from hair protein removal to irritated, itchy skin. So, will those sulfates kill you? Probably not. But can they kill your hair? Well…
At this point, we've mentioned the effects of sulfates on hair, and you don’t have to be a cosmetic chemist to understand that healthy hair and product buildup don’t mix. Now we’re ready to dive into just how bad they are.
Sulfates can cause a range of damage to your hair. For starters, they can trigger protein removal and contact dermatitis — the former, a long-term problem, and the latter, a short-term one. These cleansing agents can contribute to problems like dryness and require a dermatological intervention with medicated shampoos and skincare agents to address.
But let’s dig deeper on this.
Hair is made of protein — in fact, hair itself is a protein filament. When the protein that makes up each of your hairs is damaged, it can weaken the hair, affecting its strength and appearance.
Sulfates are closely linked with damage to hair protein because, along with the grime, these cleansing agents can also wash away your healthy hair — almost literally.
One study from 2005 showed that hair immersed in a sodium dodecyl sulfate solution loses two times as much protein as hair immersed in water. This can lead to split ends, breakage and hair that’s difficult to manage.
This problem may affect different hair types differently — fine hair and color-treated hair might be more susceptible than curly hair.
Because of this, sulfates are best avoided if you want to optimize your hair’s health, appearance and strength.
As a dermatology professional will tell you, sulfates not only strip hair protein. In some people, they can cause severe skin irritation and a painful allergic rash — a condition called contact dermatitis.
Studies suggest that people with low levels of ceramides — a type of waxy lipid molecule found in your skin cells — are more likely to experience skin irritation and contact dermatitis after exposure to sulfates such as sodium lauryl sulfate.
Not everyone will experience skin rashes or dermatitis after using shampoo or conditioner that contains sulfates. Still, it’s best to avoid shampoos that contain sulfates just in case, as there’s nothing fun about dealing with a scalp rash and the resulting itchy scalp.
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No, sulfates do not directly cause hair loss. While sulfates aren’t directly linked to male pattern baldness, they’re best avoided if you have sensitive skin or naturally thin hair.
As we’ve covered before, a combination of hormones and genetics cause male pattern baldness — namely, a genetic sensitivity to something called dihydrotestosterone, or DHT. Sulfates aren’t currently known to affect scalp DHT levels and, as such, aren’t directly linked to pattern hair loss in men.
However, sulfates can be indirectly linked to male hair loss. If you’re susceptible to skin irritation from sulfates, you could temporarily lose hair as a result of irritation, turning those particular cleansers into hair loss shampoos. It’s also possible for protein loss from excessive exposure to sulfates to weaken your hair, making breakage more likely.
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If you’ve made the decision to avoid sulfates, you’re in luck: reducing your level of exposure to sulfates is simple — just switch from your current shampoo to a sulfate-free option.
But there are some takeaways we’d like to leave you with before you go trashing stuff in your bathroom:
Compared to sulfate-based shampoos, sulfate-free shampoos can feel a little different. There’s less of a foaming, bubbling effect, meaning it can require some extra water to rinse sulfate-free shampoo from your hair.
Sulfate-free shampoos can also feel less intense, meaning you may not get the “cleansed” feeling you would from a typical shampoo. The shampoo is still effective, but the lack of foaming chemicals can mean it doesn’t have such a pronounced feel on your scalp.
It’s also worth reading the ingredient label on your other products — from body wash to toothpaste and conditioner — as many mass-market conditioners use ingredients like sodium lauryl sulfate or sodium dodecyl sulfate.
One final word: switching your shampoo isn’t all you can (or should) do. You may also want to explore other forms of hair loss treatment to supplement your shampoo.