Sulfate Shampoos Are Not Bad for You. Here’s Why.

Alyssa Brown • May 04, 2023

Sulfate shampoos are not bad for you. In fact sulfates are perfectly fine for most people’s hair and scalp. They’ve been one of the most common ingredients in shampoos for nearly a century (1), ever since Hans Schwarzkopf invented the first liquid shampoo in 1927. Sulfates in shampoos are surfactants which is the part of the shampoo or beauty product that cleans dirt and other debris off your scalp and hair.

In addition to shampoo, you’ll find sulfates in household products like laundry detergent, toothpaste, facial cleansers, and luxurious bath bombs.

But despite how common they are, sulfates have come under fire over the past several years as companies started marketing sulfate-free products, and alternative hair cleaning movements like curly girl and no-poo have made their way across social media. It doesn’t mean these techniques are right or wrong, it just means sulfate shampoos took an unfair blow to their reputation.

Much of the bad press around sulfates comes from confusion around the word “sulfate” as well as from a misunderstanding of how the sulfates function in shampoo. So, what’s the truth about sulfates in shampoos? Let’s “lather up” and dive in.

What do sulfates do in shampoo?

Sulfates are used as surfactants in shampoos, and surfactants’ primary job is to clean your hair and scalp from the debris that gets trapped within the natural oils your body produces. The main oil is a substance called sebum which your body uses to keep your scalp and hair moisturized as a layer of protection from the elements. But dirt, excess skin cells, and all sorts of other things can get stuck in sebum, which is why you get a grimy feeling if you haven’t cleaned your hair in a while.

Because sebum is largely an oil, water alone can’t clean the excess off your head. This is where surfactants come in. Think of them as a stick with a hook on each end. One hook latches onto the dirt/oil/other stuff on your head and the other hook latches onto the water molecules as they pour over your head. This is how shampoo cleans your scalp and hair while just running water over them will not. So how did sulfate shampoos get known as “bad for you?”

Why do people say sulfates are bad?

People say that sulfates are bad because of the types of sulfates. Not all may be good, and not all are actually bad. It also depends on which types of sulfates are used in the shampoo and products you use. “Sulfates” are a generic chemistry term that represents a wide variety of molecules, many of which you won’t even find in shampoos.

For example, Chondroitin Sulfate is a naturally occurring chemical found in human cartilage and has been associated with breast cancer (2). But on the other hand, it has also been associated with lower rates of colorectal cancer (3). See how tricky this can get?

A different chemical called Hydrazine Sulfate is also a cancer treatment (4). So it’s no wonder there is much confusion around the myth that “sulfates cause cancer” even though there is no evidence to support the myth (5). It is similar to MSGs in food being unsafe when they actually are. It’s an urban legend that spiraled out of control and became common belief, even though it isn’t factual.

In shampoos, you’ll find totally different sulfates. The 3 most common you’ll see are sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), and ammonium laureth sulfate (ALES). Of these 3, SLS is the most powerful cleanser, and is also another source of confusion.

There was one study (6) that showed a link between SLS and protein loss in hair, but the study had two major problems. For one, a significant portion of the protein loss was due to hotter water temperature, like when water was at 104 degrees (i.e. the standard maximum temperature on most hot tubs) and at 158 degrees (i.e. scalding water).

For another, the study used a solution with only SLS, and the solution had a high concentration. In isolation, SLS can be harsh on skin, but look at any shampoo off the shelf and you will struggle to find SLS without SLES or other sulfates. The formulation of shampoo makes a huge difference in how the sulfates interact with your hair and scalp, and the moisturizing properties of laureth sulfates make shampoos perfectly fine for normal scalps (7).

Another source of confusion comes from people blaming sulfates for things that weren't their fault. Similar to the misconception about MSGs. People would use a shampoo and have a reaction to it, so they immediately blame the sulfates as bad for your hair and scalp. Shampoo formulations vary widely from brand to brand, and even within the same brand, so you might be getting a reaction from different concentrations of the various ingredients in the shampoo. Other ingredients like perfumes, anti-bacterial additives, and more can all cause you to have a reaction (8), so it may not have been the sulfates at all. They’re just an easy scapegoat.

And make sure you’re not washing your hair too frequently. Depending on your hair type and activity levels you’ll want a certain number of days between washes because regardless of what type of shampoo you use. Washing too often strips off the protective sebum and dries out your hair and scalp, and this is also a situation where some people blame sulfates, but it was the frequency of washing instead.

Should anyone worry about sulfates in shampoo?

Even though the FDA (9) and nearly 100 years of people using sulfate shampoos prove they’re safe for the vast majority, there are some people that should avoid sulfates in shampoo. Sulfates might irritate people with sensitive skin conditions like eczema or psoriasis, and anyone with ordinarily dry hair might find sulfates make their hair even dryer (10).

People that have color, perm, and other chemical treatments might also benefit from sulfate-free products. The color/chemical treatments can weather the hair by damaging the outer cuticle layer or drying out the inner cell membrane complex, which makes their hair more fragile to begin with. This is why the curly girl method for cleaning hair can be a good alternative.

And because color treatments can damage the cuticle layer of your hair shaft, it’s easier for the hook of the sulfate/surfactant to grab onto the color molecules (instead of latching onto dirt molecules) during a shampoo, which is why you often hear people say not to use sulfates if you dye your hair.

How do sulfate-free shampoos clean without the sulfates?

The sulfates in shampoos are surfactants, but there are surfactants that are not sulfates. Often these non-sulfate surfactants might be “milder” on the hair, but they also tend to remove less dirt and oil. Plus, the second role of many sulfates in shampoo is a lush lather. This is why you might not get all the bubbles when using a sulfate-free shampoo.

So, now that you know the truth behind if sulfate shampoos are bad for you. No, sulfate shampoos are not bad for most of us and you likely have nothing to worry about if you use them. Follow good grooming habits, and if you use a shampoo that does makes your scalp itch, or that gives you a bad reaction, you might think about seeing a medical professional for allergy testing to see if you’re allergic to something in the shampoo. Subscribe to our newsletter below for more hair nutrition and styling tips like this one.

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