July 20, 2026

Elien Degraeve

The Truth About Sulphates in Shampoo Bars (Are They Really Bad?)

Most of the sulphate debate is about your body. The health concerns are real. But if you're washing your hair with a solid bar, there's a second argument that almost nobody's making. It's about what sulphates do to your hair. And it applies regardless of how sensitive you are.

What Sulphates Are

Sulphates are surfactants. Their job is to lift oil and dirt from your hair and scalp so water can rinse it away. They're what creates lather.

The two main sulphates in hair products are Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES). Both do the same basic job. SLES is a milder, ethoxylated version of SLS. Same family. Different intensity.

Sulphates work. They're cheap, effective, and produce the foam most people associate with a clean. Which is why they've been the industry default for decades.

The Health Concerns Are Real

SLS is a known skin and scalp irritant. The evidence on this is solid, not social media speculation.

Repeated exposure to SLS can strip the skin barrier, cause dryness, trigger sensitivity responses, and worsen conditions like eczema and psoriasis. For people with reactive skin or scalps, SLS is a reasonable thing to remove from the routine.

SLES is milder. Most of the stronger research is about SLS specifically, and the two molecules behave differently. Worth knowing, because many brands use SLES not SLS and the distinction matters.

The carcinogen claim circulates constantly, but there are actually two different claims in there. The first one, that SLS directly causes cancer, has no credible scientific basis. It's not classified as a carcinogen by IARC, NTP, the EPA, or the EU.

SLES is different.

The ethoxylation process that makes SLES milder than SLS can leave behind 1,4-dioxane as a manufacturing contaminant. 1,4-dioxane is classified as a possible carcinogen. That's a separate concern, and a legitimate one.

The health concerns are real and they affect enough people to take seriously. But if you're washing your hair with a shampoo bar, there's a second reason to care about sulphates that has nothing to do with what they do to your body.

What They Also Do to Your Hair

Your hair and scalp prefer a slightly acidic environment, roughly pH 4.5 to 5.5. At this pH, the hair cuticle lies flat. It looks smooth, holds moisture, and reflects light. Move too far outside that range and the cuticle lifts, leading to frizz, tangling, dryness, and breakage.

Here's the problem with sulphates in a bar format.

Many products sold as shampoo bars are actually soap bars with some hair-friendly ingredients added. Traditional soap is made by saponification and sits at a pH of around 8 to 10. That's fine for skin. It's too high for hair. When sulphates are used in this kind of formulation, the pH problem compounds.

When you wash with a high-pH bar, the cuticle lifts and stays lifted until the pH normalises. This is what causes the waxy, heavy, rough feeling that people report when switching to the wrong kind of shampoo bar. It's not a detox. It's a pH mismatch. Our post on why hair feels different when you switch to shampoo bars covers this in detail.

In liquid shampoo, pH is easier to control regardless of surfactant. In a bar, the formulation approach makes a much bigger difference to the final pH. Sulphate-free surfactants used in a properly formulated bar work at the right pH for hair. Sulphate-based ones typically don't.

So you have two reasons to care: what sulphates do to your body, and what they do to your hair. In a shampoo bar, both apply.

What Sulphate-Free Bars Use Instead

If not SLS or SLES, what's doing the cleansing?

Sodium Cocoyl Isethionate (SCI): derived from coconut fatty acids. Mild, produces a good lather, and works at a pH that's gentler for hair.

Cocamidopropyl Betaine: coconut-derived, often used alongside other surfactants to improve gentleness and conditioning.

Sodium Cocoyl Glutamate: amino acid-based, very mild, good for sensitive scalps.

The ingredient names are a mouthful. The result isn't complicated: a bar that cleans without stripping, at the pH your hair actually needs.

These alternatives typically produce less lather than sulphate-based bars. Less foam doesn't mean less clean. It means a different surfactant doing the same job more gently.

For a closer look at how to read a shampoo bar ingredient list, How to Read a Shampoo Bar Ingredient List walks through it step by step.

Who This Matters For

Both concerns, health and hair, don't hit everyone equally. But they hit more people than know it.

Sensitive or reactive skin and scalps. The health case is strongest here. SLS irritation is well documented for reactive skin. Sulphate-free removes one significant trigger. The Scalp Soothe Unscented Solid Shampoo Bar is fragrance-free as well, for scalps that need the least possible provocation.

Colour-treated hair. Sulphates accelerate colour fade by stripping pigment molecules from the hair shaft. If you're spending money on colour, using sulphates to wash it out is a reasonable thing to stop doing. The Everyday People Solid Shampoo Bar works for most normal and colour-treated hair.

Bleached or chemically processed hair. Chemical processing makes hair more porous and more susceptible to stripping. The Hyper Hydrating Solid Shampoo Bar is built for hair that's already been through something.

Curly and textured hair. Curly hair is naturally drier because the curl pattern makes it harder for scalp oils to travel down the shaft. Sulphates strip the oil it already struggles to retain. The Creamy Curls Solid Shampoo Bar is built for thick, curly and frizzy hair. The complete guide to shampoo bars for curly hair covers this properly.

Everyone washing their hair with a bar. This is the one the industry doesn't say loudly enough. The hair argument (pH, cuticle behaviour, formulation approach) applies to anyone using a solid bar. Sulphate-free in a bar format isn't a sensitivity preference. It's the better formulation decision for how hair works.

Not sure which bar suits your hair? How to Choose the Best Shampoo Bar for Your Hair covers hair type matching in detail.

What you're saying

"My hair feels stripped and tight after every wash."

That's the SLS. It removes oil more aggressively than your scalp needs. The scalp compensates by producing more, so you wash again sooner, and the cycle continues. It's not your hair type. It's the surfactant.

"The natural hair shampoo bar leaves my hair feeling clean, not stripped like chemical shampoos. I would not go back now."

Joanne C., Everyday People Solid Shampoo Bar

"I switched to a shampoo bar and my hair lost its shine."

Usually a pH problem. A bar formulated too high keeps the cuticle open after washing. Open cuticle scatters light instead of reflecting it. The hair looks dull, feels rough, tangles more easily. Sulphate-free bars formulated at the right pH let the cuticle close properly.

"The shampoo has made my hair lovely and shiny and looks thicker. I have very fine hair."

Ann D., Everyday People Solid Shampoo Bar

Frequently Asked Questions

Are sulphates actually bad for you?

SLS is a known skin and scalp irritant. That's well established, not internet rumour. For people with sensitive skin, eczema, psoriasis, or reactive scalps, it's a real concern. The direct SLS-causes-cancer claim has no scientific basis. The SLES question is more nuanced: the ethoxylation process that makes SLES milder can leave behind 1,4-dioxane, a manufacturing contaminant classified as a possible carcinogen. Different claim, different evidence. Both are reasons to care.

What's the difference between SLS and SLES?

Both are surfactants that clean hair by lifting oil and dirt. SLES is a milder version produced by ethoxylation. Most of the stronger research on irritation is about SLS specifically. They're the same family but not the same molecule, and many brands use SLES rather than SLS because it's gentler.

Why do sulphates matter more in a shampoo bar than liquid shampoo?

In liquid shampoo, pH is easier to control regardless of surfactant. In a bar, the formulation approach has a much bigger impact on the final pH. Many shampoo bars are soap-based and sit at a pH of 8 to 10. That's too high for hair. Sulphate-based bars in that formulation approach compound the problem. Sulphate-free bars made with milder surfactants are much more likely to be formulated at the pH hair actually needs, around 4.5 to 5.5.

Does sulphate-free mean less lather?

Often yes. Milder surfactants produce less foam than SLS. Less lather doesn't mean less clean. It means a different surfactant doing the same job with less stripping. Most people adjust within a few washes.

Do I need sulphate-free if my hair seems fine?

The health concerns vary by person. The hair concerns in a bar format apply more broadly. If you're washing your hair with a solid bar, the pH argument for sulphate-free applies regardless of hair type. Sulphate-free isn't just a sensitivity preference in a bar. It's the better formulation approach for how hair works.

Are Viva La Body shampoo bars sulphate-free?

Yes. All five are sulphate-free and pH balanced for hair. Sulphate-free alone isn't enough if the pH is wrong, which is why both matter and why we built for both.

Why does my hair feel waxy or rough after switching to a shampoo bar?

Usually a pH problem, not a detox. A high-pH bar lifts the hair cuticle and it stays rough until the pH normalises. Most common with soap-based bars. A sulphate-free, pH-balanced bar avoids most of this from the start. How to speed up the shampoo bar transition covers what to do if you're mid-switch.

Is sulphate-free better for colour-treated hair?

Yes. Sulphates accelerate colour fade by stripping pigment from the hair shaft. If you're colouring your hair, sulphate-free shampoo extends how long it lasts. Bleached or chemically processed hair also benefits because processing makes the hair shaft more porous and more susceptible to stripping.

Real talk.

The sulphate debate has spent twenty years on one question. Mostly looking the wrong way.

The health concerns are real. The hair concern is different but just as real. Neither goes away because a label says sulphate-free.

We built Viva La Body bars around both. Sulphate-free and pH balanced, every one.

Everyday People, Creamy Curls, Balance Bar, Hyper Hydrating, Scalp Soothe.

Made them this way because the right answer existed. Seemed worth using.