Medically reviewed by Patrick Carroll, MD
Written by Our Editorial Team
Last updated 3/2/2020
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 as sulfates, these ingredients help shampoo mix into water, creating the foamy texture 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 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.
Sulfates are found in a variety of products, from shampoo to dish liquid and laundry detergent. When used in shampoo, ingredients like sodium lauryl sulfate essentially amplify the effects of the shampoo, allowing it to strip away more of the things that make your hair oily and uncomfortable.
This is both good and bad. Sulfates are “good” in the sense that they make shampoo far more effective. However, they’re bad in the sense that they can have too much of an effect on your scalp and hair, resulting in excess stripping away of naturally occurring proteins and oils.
Over the years, there have been persistent rumors that sulfates (including sodium lauryl sulfate, the most common sulfate in hair products) can potentially cause cancer.
These rumors are not 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.
However, sulfates can potentially cause damage to your hair when overused, ranging from hair protein removal to irritated, itchy skin.
Hair is made of protein — in fact, hair itself is a protein filament. About 91 percent of each of your hair fibers is protein, along with numerous other nutrients. 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. In fact, one study from 2005 shows 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 is difficult to manage.
Because of this, sulfates are best avoided if you want to optimize your hair’s health, appearance and strength.
Sulfates not only strip hair protein — in some people, they can cause severe skin irritation and a painful allergic rash called contact dermatitis.
Scientific studies, including one from 1996, 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 being exposed 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.
As we’ve covered before, male pattern baldness is caused by a combination of hormones and genetics — namely, a genetic sensitivity to DHT. Sulfates aren’t currently known to affect scalp DHT levels, and as such aren’t directly linked to 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. It’s also possible for protein loss from excessive exposure to sulfates to weaken your hair, making breakage more likely.
Reducing your level of exposure to sulfates is simple — just switch from your current shampoo to a sulfate-free shampoo. It’s also worth reading the ingredient label on your conditioner, as many mass market conditioners use ingredients like sodium lauryl sulfate or sodium dodecyl sulfate.
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” feel 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.
However, the long term results — in terms of hair health, hair protein retention and damage prevention — mean it’s definitely worth making the switch from a typical mass market shampoo to a healthier sulfate-free shampoo.
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