Are sulfates bad for hair?

Are sulfates bad for hair? 

Sulfates aren't inherently bad for hair, but they're not right for everyone. Their strong cleansing action can strip natural oils, which may lead to dryness and frizz for some hair types — particularly curly, dry, or colour-treated hair. For oily hair or scalps with product buildup, sulfates are effective and often the better choice. It comes down to your hair type and what it needs. Ethique offers both sulfate and sulfate-free shampoo bars so you can choose what works for you.

What are sulfates?

Sulfates are a type of cleansing agent - surfactants that create lather and lift oil and dirt from your hair and skin. They're a common ingredient in shampoos, body wash, toothpaste, and plenty of other personal care products. Also in cleaning products, which is partly where the bad press comes from. People hear "it's in floor cleaner" and assume it shouldn't be near their hair.

The sulfates you'll see most often are sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), and ammonium lauryl sulfate. But these aren't the only ones. Sulfates are a large family of compounds -some harsh, some surprisingly gentle. Whether a sulfate is too strong for your hair depends on which one it is, not the word "sulfate" itself.

So are they actually bad?

Here's what the research says: there's no scientific evidence that all sulfates are drying, irritating, or strip color and keratin. None. Studies have specifically looked into this, and the results don't support the claims you see on social media.

What makes a surfactant harsh isn't the sulfur group in the molecule. It's the overall size and structure. Some sulfates are harsh. Others are mild enough for baby shampoo. You can't tell from the word "sulfate" alone whether a product will be too strong for your hair.

One more thing: you can't determine how harsh a shampoo is by looking at a single ingredient. Formulation matters. How much of the ingredient is used, what it's combined with, and the pH of the final product – all of this affects how it feels on your hair and scalp.

Where did the bad press come from?

A few places.

The curly girl method popularised sulfate-free shampoos for curly hair, and for good reason — curly and coily hair types tend to be drier and benefit from gentler cleansing. But "works well for curly hair" became "sulfates are bad for everyone," which isn't the same thing.

There's also confusion between different sulfates. SLS is a strong cleanser. It's effective, but it can be too effective for some people - stripping natural oils and leaving hair dry. But sodium coco sulfate, for example, uses a blend of fatty acids from coconut and is considerably milder. Same word in the name, different ingredient in practice.

And then there's the "it's in industrial cleaners" argument. Yes, some surfactants are in cleaning products. But concentration matters. Water is in radiator fluid - doesn't mean water is dangerous.

Can sulfates cause itchy scalp or hair loss?

Scalps are sensitive to all kinds of things, including hair products, weather, stress, medication, and hormones. If your scalp is itchy or irritated, it's nearly impossible to pin that on one ingredient in an entire formulation. Could be the fragrance. Could be something else entirely. Patch testing new products is always a good idea if you have sensitive skin or known skin conditions.

As for hair loss - that's almost always hormonal or genetic, not caused by shampoo ingredients. Hair growth is cyclical, and most people go through periods of shedding. If you switched shampoos around the same time, it's easy to blame the product. But sulfates don't penetrate the hair shaft deeply enough to affect the follicle or disrupt your hair growth cycle.

If you're experiencing significant hair loss, see a dermatologist. No shampoo – sulfate or sulfate-free – is going to fix a hormonal issue.

When sulfate-free actually makes sense

None of this means that sulfate-free shampoos are pointless. For some hair types, they are genuinely the better choice.

Curly and coily hair tends to be drier because natural oils have a harder time travelling down the hair shaft. Gentler surfactants help preserve those natural oils. The curly girl method recommends sulfate-free for this reason, and a lot of people with curly hair find their curls behave better without sulfates.

Color-treated hair can also benefit. While there's no strong evidence that sulfates strip hair color faster than other surfactants, gentler cleansing is generally kinder to chemically processed hair. The same goes for keratin treatments and other chemical treatments - if you've invested in a salon service, a milder shampoo helps protect that investment.

If your scalp is sensitive or your skin reacts easily, sulfate-free shampoos are worth trying - they're usually formulated to be gentler overall. Same goes for dry, frizzy hair, particularly in winter or dry climates when moisture is already harder to hold onto.

When sulfates work better

On the other hand, some hair types actually do better with sulfates.

Fine hair can get weighed down by heavy conditioners and styling products. A sulfate shampoo cuts through product buildup more effectively, giving fine hair lift and volume.

Oily scalps need a deeper cleanse. Sulfate-free formulas don't always cut through excess oil effectively — you might end up with flat, greasy-looking hair by day two.

If you swim regularly, live in a hard water area, or use a lot of styling products, you'll probably want a clarifying shampoo with sulfates occasionally — even if your regular shampoo is sulfate-free.

How good formulation changes everything

Here's something hair experts don't talk about enough: the number of surfactants in a formula matters more than which specific ones are used.

One surfactant on its own tends to be harsher. Two is gentler. Three is better still. A well-formulated sulfate shampoo with multiple surfactants, used at the right concentration, can be gentler than a poorly formulated sulfate-free one.

This is why "sulfate-free" isn't automatically better. It depends entirely on how the product is made.

Finding what works for your hair

Your hair goals are more important than ingredient dogma. If your hair feels good – not stripped, not weighed down, colour lasting, scalp is comfortable – your shampoo is working. Whether it contains sulfates or not is secondary.

If you're unsure, experiment. Try a sulfate-free shampoo for a few weeks and see how your hair responds. Or try a gentle sulfate formula if sulfate-free isn't giving you enough cleansing power. Some people rotate between both — a gentler wash most days, a deeper cleanse when needed.

There's no universal answer. Hair types vary. So do scalps, water quality, styling habits, and climate. What works for someone on social media might not work for you.

The bottom line

Sulfates aren't the villain they've been made out to be. Some are harsh, some are gentle, and formulation matters more than any single ingredient. Sulfate-free shampoos are great for certain hair types - curly, dry, colour-treated, sensitive - but they're not automatically safer or better for everyone.

Pay attention to how your hair actually feels. That's a better guide than any ingredient list.