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Sulfates have gotten an incredibly bad reputation in the beauty world—often akin to tanning beds and gritty facial cleansers. This is due to some serious misinformation. In the late ‘90s, rumors began circulating that some chemicals found in shampoos, particularly sulfates, could potentially cause cancer. But unlike tanning beds, there is no direct evidence linking sulfates to cancer—or infertility and developmental issues, which are also often falsely associated with the ingredient.
Long story short, sulfates are not really a big deal. So what’s the deal with the whole “sulfate-free” brigade? When it comes to haircare, some brands choose to formulate products without sulfates because they can sometimes be too effective at cleaning, leaving hair dry and brittle. But aside from any possible drying effects, there is little risk to a person’s health from using sulfates correctly.
In fact, they can actually be quite beneficial, especially in haircare products. Meet sodium trideceth sulfate (STS), the gentlest of sulfates around. To debunk the rumors and learn the truth about STS, we went straight to the experts. Read on for why STS isn’t as scary as it might seem.
Meet the Expert
- Kari Williams, MD, is a board-certified trichologist and licensed cosmetologist, as well as a member of DevaCurl’s Expert Curl Council.
- Gaby Longsworth, PhD, is a scientist and hair expert with extensive research on all types of wavy and curly hair. She’s the owner of Absolutely Everything Curly and received her Hair Practitioner Certificate through the International Association of Trichologists.
Sodium Trideceth Sulfate
Type of ingredient: Surfactant
Main benefits: According to Williams, STS helps cleanse the hair and remove product, oil, and dirt buildup.
Who should use it: Most anyone can use products with STS in it. Though if there is a pre-existing scalp condition, skin sensitivities, or allergies, Williams suggests consulting with a dermatologist or doctor.
How often can you use it: Daily
Works well with: STS works well with other surfactants and cleansing agents. It also works nicely with moisturizing oils, like coconut oil and argan oil, which can help soothe any potential irritation.
Don’t use with: Other sulfates, especially those harsher and more drying on the hair.
What Is Sodium Trideceth Sulfate?
Sodium trideceth sulfate (STS) is a cleansing agent that belongs to the chemical class of alkyl ether sulfates. It acts as a cleansing agent in personal products and creates a foaming sensation. Since it’s part of the gentlest class of surfactants and cleansers, it’s commonly found in haircare products. To get real scientific about it, the chemical name is sodium 2-(2-(2-(tridecyloxy)ethoxy)ethoxy)ethyl sulfate, according to Longsworth.
Benefits of Sodium Trideceth Sulfate
STS is found in a variety of personal cleansing products thanks to its surfactant qualities and gentle nature. It’s most often used in shampoos and conditioners and has a handful of benefits:
- Improves overall hair health: STS is an excellent cleansing agent thanks to its emulsifying properties. When hair is not properly cleansed, hair can begin to lose its luster and even become dry and brittle.
- Reduces inflammation: According to Williams, part of the reason STS is so common in haircare is its disinfecting quality, which effectively calms and soothes inflammation.
- Removes dirt, oil, and product buildup: STS is an ideal cleansing agent, since it helps water mix with oil, dirt, and product buildup on the scalp so that they can be easily rinsed away.
Hair Type Considerations
In general, sulfates are ideal for those with greasy hair thanks to their superior cleansing abilities. And it’s true, sometimes sulfates are such effective cleansers that they end up stripping the hair of natural oils and nutrients. That being said, STS is part of the gentlest class of surfactants and cleansers. Williams says that STS is often formulated into haircare products specifically to enhance cleansing products without drying out the scalp and hair. And while she says there are really no specific hair type considerations, she does point out that those with pre-existing scalp conditions, skin sensitivities, and allergies should consult with a doctor or dermatologist.
Meanwhile, Longsworth says that STS could be a good alternative for those with curly hair and colored hair—a mild surfactant like STS won’t strip colored hair or leave curls dry and brittle. While it’s a gentle sulfate, the side effect of scalp irritation and dryness is still a possibility with consistent or overuse of the ingredient—though both doctors emphasize that the possibility is small and fairly unlikely. Think of it like using a chemical exfoliant on your face. Even with the gentlest acids, there’s always a little bit of risk.
It’s also important to note that frequency of use can come into play. For those with drier scalps or hair who find STS irritating, consider incorporating the ingredient into your hair routine perhaps a few times a week, rather than daily. Longsworth also mentions that there are better, milder non-sulfate alternatives available, such as sodium lauroyl methyl isethionate.
How to Use It
STS is most commonly found in shampoos and cleansing conditioners, according to Williams. STS is often found in products claiming to be gentle, nurturing, calming, repairing, etc.—you get the idea. Follow product instructions and use as you normally would.