In a beauty world where we’re constantly told to forgo popular ingredients because they could cause harm to our skin and hair, it can be hard to determine what’s legit and what’s just classic fearmongering. Among the most popular debates is whether or not sulfates are bad for your hair. They’re included in so many hair products; they can’t be that bad, right? The answer to that is actually a bit more nuanced than you might think.

Because sulfates are so good at wiping away oil and debris, they can be too drying for some. That's why sulfate-free shampoos have become more and more popular over the past decade. “Sulfates shouldn’t be viewed as a bad ingredient,” says Leland Olson, style-color master from Kevin Murphy. “However, due to the nature of their incredible cleansing capabilities, they can remove color and moisture from the hair." This is primarily an issue for those with color-treated hair, extremely dry/brittle hair, or those with a sensitive scalp.

"Sulfates are essentially a cleansing agent," says board-certified dermatologist Marisa Garshick, MD. "They're a type of surfactant that's often added to shampoos to provide more of a deep, thorough cleanse. Oftentimes, it's what contributes to that foaming, lather effect." Celine de Water, the product developer for Balmain Hair, explains that the two most common types of sulfates in hair products, sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES), are used to cleanse the hair and remove dirt, oil, and build-up on strands and your scalp. Olson adds that sulfates have a smaller molecular structure that allows them to deeply penetrate the hair.

Olson also says that most brands like to use sulfates because they are an inexpensive ingredient that is really effective in stripping away dirt and oil. Luckily, shampoo formulations have evolved for the better, so shampoos with sulfates aren't as drying as they used to be. "There's been a greater appreciation for scalp and hair health over the past 10 to 15 years," says Dr. Garshick. "Brands are essentially adding ingredients that have a positive impact on hair health. So even shampoos that have a sulfate-based surfactant are incorporating different types of conditioning agents or hydrating ingredients, combating that potential for dryness and irritation."

So long as your shampoo isn't causing any issues and you're not chemically processing your hair, there's no need to go sulfate-free. And if you have a lot of excess oil on your scalp or use a lot of products that lead to buildup, you'll likely prefer a shampoo with sulfates since they provide a deeper cleanse. "It really comes down to personal experience," she says.

To check whether your hair shampoo is sulfate-free or not, de Water says that you can look for terms like "sodium lauryl sulfate" (SLS) or "sodium laureth sulfate" (SLES) on the ingredient list. Olson says that the product is probably sulfate-free if you don't see those ingredients listed. "Manufacturers are required to list all ingredients on the packaging of their products so consumers can verify listed ingredients and chemicals used in said product," he adds. 

When to Consider Sulfate-Free Products

So while sulfates shouldn’t be considered a “bad” ingredient for your hair, there are a few reasons why you may consider going sulfate-free. If your hair is particularly dry, Olson says that sulfate-free shampoos are going to help maintain the natural oils in your hair that you need while also providing a thorough cleanse.

“Hair will be more likely to be noticeably shinier, softer, and healthier [after using a sulfate-free shampoo],” he says. "Fine-haired clients, coarse/thick-haired clients, and curly-haired clients will benefit the most from using a shampoo that is sulfate-free, as these types of hair tend to already lack the moisture they need naturally.”

You should also steer clear of sulfates if you're coloring your hair, as Olson says sulfates can cause the color to fade prematurely. "My primary concern with any color client is color retention and longevity,” Olson says. "[Coloring hair] is an investment, and using a product that contains sulfates will strip the hair’s color out faster, resulting in dull, lackluster hair color."

Dr. Garshick adds that sulfates can also cause irritation for those with a sensitive scalp. "If you're experiencing flaky, itching, or anything on the scalp that you are concerned about, it is worth looking at the ingredients of the shampoo because sulfates can cause an allergic contact dermatitis," she says. If this is the case, de Winter says to give "sulfate-free a try for a week and see if it changes anything for you. This can help you figure out if sulfates are what's making you feel irritated.”