What is Sodium Laureth Sulfate? Why is Sodium Laureth Sulfate (SLES) different to Sodium Lauryl Sulfate (SLS)? 

Sulfates get a lot of bad press in haircare. But when you are formulating for dandruff-prone scalps, the question is not simply “sulfate or sulfate-free?” The better question is: does the shampoo clean the scalp properly without being harsher than it needs to be?

At Hairetic, we use Sodium Laureth Sulfate, also known as SLES (different to SLS), in our shampoos because it gives the level of cleansing we believe dandruff-prone scalps need. It helps remove oil, sweat, flakes, styling product build-up and everyday grime from the scalp. We also formulate with mildness in mind, using SLES carefully rather than simply chasing maximum foam.

Our products are dermatologically tested on sensitive skin, because we know that people with dandruff-prone scalps often also deal with itching, irritation and sensitivity.

You will notice a lower level of foaming compared to a regular 'mass' anti-dandruff shampoo. In addition, you may even feel your hair is less 'squeaky' after washing, as some of the natural oils in your hair are left (rather than being entirely stripped out by a heavy load of surfactants).

First: what are sulfates?

Sulfates are a type of cleansing ingredient called a surfactant. Surfactants help water mix with oil and dirt so they can be rinsed away. In shampoo, they help lift scalp oil, sweat, flakes and product residue from the hair and scalp.

The two sulfate names people often confuse are:

• Sodium Lauryl Sulfate (SLS)
• Sodium Laureth Sulfate (SLES)

They sound similar, but they are not the same.

SLES vs SLS: what is the difference?

Sodium Lauryl Sulfate (SLS) is a strong cleanser and foaming agent. It is effective, but it is also widely used in dermatology as a standard irritant in skin testing because it can disrupt the skin barrier at certain concentrations and exposure levels.

Sodium Laureth Sulfate (SLES) is related to SLS, but it is ethoxylated, which changes its behaviour and generally makes it milder in rinse-off products. In simple terms: SLES gives effective cleansing and foam, but is usually considered a gentler option than SLS.

Why dandruff-prone scalps need effective cleansing

Dandruff is often linked to scalp oil, flakes, irritation and the yeast Malassezia, which naturally lives on the scalp. This yeast feeds on scalp oils, so allowing oil and build-up to sit on the scalp for too long can make the scalp environment feel worse for some people.

That is why a dandruff shampoo needs to do more than smell nice or feel “natural”. It needs to cleanse the scalp properly.

SLES helps remove:

• excess scalp oil
• sweat and daily grime
• dead skin and visible flakes
• dry shampoo residue
• styling product build-up
• pollution and environmental dirt

For dandruff-prone scalps, that cleansing step matters. A shampoo that is too mild may feel nice on first use, but if it leaves oil and residue behind, it may not do enough for people who are dealing with flakes and build-up.

Why we prefer SLES to SLS

We chose SLES because it gives us a better balance between cleansing power and mildness. SLS can clean very effectively, but it can also be more stripping. SLES allows us to create a shampoo that lathers, rinses well and removes build-up, while still being suitable for a formula designed with sensitive scalps in mind.

For Hairetic, the aim is not to make the harshest possible cleanser. The aim is to make a shampoo that is effective enough for dandruff-prone scalps, but considered enough for regular use.

The amount used in a formula matters a lot. A baby shampoo can use SLES very safely in small amounts, and a clarifying shampoo for long hair will use far more. At Hairetic, we spent 3 years perfecting the balance between SLEs and other cleaning ingredients to give the best option for anyone with a sensitive scalp.

Why not just use “natural” surfactants?

We tested (many!) more naturally derived surfactant systems during development. Some were promising, but they did not give us the performance we wanted for a dandruff-focused shampoo.

The main issues we found were:

• Weaker oil removal: Some natural surfactants did not remove scalp oil and build-up as effectively.
• More residue: Some left the hair or scalp feeling coated rather than properly clean.
• Poorer rinse feel: Some formulas were harder to rinse cleanly from the hair.
• Less consistent foam: Foam is not everything, but it helps people spread shampoo evenly across the scalp.
• Less reliable performance with actives: In a dandruff shampoo, the whole formula has to work together, including the cleansing system and anti-dandruff active.

Natural does not automatically mean milder, and synthetic does not automatically mean harsh. What matters is the final formula: the surfactant blend, concentration, pH, conditioning agents, anti-dandruff active, and how the product performs on real skin.

Is sulfate-free always better?

No. Sulfate-free shampoos can be great for some people, especially those with very dry hair, colour-treated hair or specific sensitivities. But sulfate-free does not automatically mean better for dandruff.

Some sulfate-free formulas may not cleanse enough for oily, flaky or product-heavy scalps. If flakes are being made worse by oil and residue build-up, a very gentle cleanser might not be the best choice.

For dandruff-prone scalps, we believe the best shampoo is one that cleans properly while still being formulated for mildness.

Why percentage matters

Ingredients are not “good” or “bad” in isolation. The amount used matters. A high level of a strong cleanser can feel stripping, while a carefully balanced level can give effective cleansing without unnecessary harshness.

That is why Hairetic uses SLES deliberately and carefully. We do not use it simply to create huge foam. We use it because it helps cleanse the scalp effectively, and we balance it within a formula designed for dandruff-prone and sensitive scalps.

Dermatologically tested on sensitive skin

Because dandruff-prone scalps can be reactive, our shampoos are dermatologically tested on sensitive skin. This does not mean no one will ever react to the product, because individual sensitivities can still happen, but it does mean the formula has been tested with scalp comfort and mildness in mind.

So, are sulfates bad for dandruff?

No. Sulfates are not automatically bad for dandruff. In fact, a well-formulated sulfate shampoo can be useful for dandruff-prone scalps because it helps remove oil, flakes and build-up.

The better question is not “does it contain sulfates?” but:

• Which sulfate is being used?
• How much is being used?
• Is the product rinse-off?
• Is the formula balanced for mildness?
• Does it clean the scalp properly?
• Has it been tested appropriately?

That is why we choose SLES over SLS, and why we do not believe sulfate-free is automatically the best route for dandruff-prone scalps.

References

1. NHS - Dandruff
2. Cleveland Clinic - Seborrheic dermatitis
3. Cleveland Clinic - Dry scalp and dandruff
4. PubMed - Comparing subclinical irritation from SLS and SLES
5. PubMed - Safety assessment of sodium laureth sulfate
6. International Journal of Toxicology - Safety assessment of sodium laureth sulfate and ammonium laureth sulfate
7. Gloucestershire Hospitals NHS - Hair care for eczema of the scalp

Frequently Asked Questions

Is Sodium Laureth Sulfate bad for dandruff?

No, Sodium Laureth Sulfate is not automatically bad for dandruff. In a well-formulated rinse-off shampoo, SLES can help remove oil, sweat, flakes and build-up from the scalp, which is important for many dandruff-prone scalps.

Is SLES better than SLS?

SLES is generally considered milder than SLS while still offering strong cleansing and foaming performance. That is why many shampoos use SLES when they want effective cleansing with a gentler profile than SLS.

Why does Hairetic use SLES?

Hairetic uses SLES because dandruff-prone scalps often need effective cleansing. SLES helps remove oil, flakes and product build-up, while allowing us to formulate a shampoo that is dermatologically tested on sensitive skin.

Our SLES is natural origin, used in lower quantities than industry standard, and perfect for anyone suffering with dandruff or a dry scalp.

Are sulfate-free shampoos better for dandruff?

No. Sulfate-free shampoos can be useful for some hair types, but they are not automatically better for dandruff. Some may not cleanse enough oil or build-up from the scalp, which can be an issue for dandruff-prone users.

Can sulfates irritate the scalp?

Any cleansing ingredient can irritate the scalp if used at a high level, used too often, or if the person is sensitive to it. This is why the final formula matters more than the ingredient name alone.

Does SLES strip hair?

SLES can feel stripping if used in a harsh or poorly balanced formula. In a carefully formulated shampoo, it can provide effective cleansing while still being suitable for regular rinse-off use.

Is SLES safe in shampoo?

SLES has been reviewed for cosmetic use and is widely used in rinse-off products such as shampoos and body washes. As with any ingredient, safety and mildness depend on concentration, formula design and how the product is used.

Is natural shampoo better for sensitive scalps?

Not necessarily. Natural ingredients and natural surfactants can still irritate sensitive skin. A good sensitive-scalp shampoo should be judged by the complete formula, not just whether the ingredients sound natural.