Sodium Laureth Sulfate

The short answer

Sodium Laureth Sulfate — usually shortened to SLES — is an anionic surfactant. Translation: it is one of the ingredients that lets a face wash actually remove oil, sweat, sunscreen residue, and the general grime of being a human in modern life.

It foams. It cleans. It is in a huge number of syndet (synthetic detergent) cleansers because it works well and is generally milder than old-fashioned soap bars.

It is also one of the most argued-about ingredients on skincare internet — which is odd, because the real story is less dramatic than the memes suggest.

SLES is not a miracle. It is not a toxin. It is a tool. And like most tools, what matters is how it is used.

What SLES actually does in a cleanser

Surfactants lower surface tension so water can lift oily debris off skin and rinse it away. Without them, you are mostly splashing water around and hoping for the best.

A 2004 review on cleanser technology^[1] explains the trade-off clearly: surfactants that interact strongly with skin proteins tend to cause more irritation, tightness, and barrier disruption. Milder syndet systems are designed to clean without treating your stratum corneum like a kitchen counter.

A 2022 review comparing soaps and syndets^[2] makes the same practical point from the other direction: synthetic detergents can maintain native skin structure far better than traditional soap, which disrupts barrier lipids and shifts pH. That is why most modern face washes — including ours — are built on syndets like SLES rather than soap chemistry.

So when someone says "I avoid all sulfates," what they often mean is "I had a bad experience with a harsh cleanser." That is valid. But it is not the same as SLES being universally harmful.

Why formulation matters more than the label

Here is the part internet skincare often skips.

SLES alone can feel invasive on skin. Takagi's 2014 study^[3] found that plain SLES increased dryness and erythema in soak tests compared with a blended surfactant system — but when SLES was combined with milder co-surfactants, the formula caused significantly less irritation while still cleansing effectively.

That is the whole game:

• Co-surfactants such as cocamidopropyl betaine reduce harshness.
• Humectants such as glycerin and sodium PCA help skin feel less tight after rinsing.
• pH near the skin's natural range (around 5.5) matters more than people realise.
• How often you wash matters. Cleansing twice daily with a balanced formula is not the same as scrubbing four times because you "feel oily."

In my experience, the people who struggle most with cleansers are not failing because SLES exists. They are using products that clean aggressively, skipping moisturiser afterward, or fighting their skin like it owes them money.

Is SLES good or bad for acne-prone skin?

For most people with oily or acne-prone skin, a gentle daily cleanse is non-negotiable. You need to remove excess sebum and surface debris without turning your face into the Sahara.

SLES in a well-built face wash can do exactly that. It is not comedogenic. It does not "feed" breakouts the way heavy occlusive oils sometimes can for some people. The bigger risks are over-cleansing, using a formula that leaves you tight and stripped, or skipping the rest of a simple routine because you believe one ingredient is the whole problem.

If your cleanser makes you wince, look at the full formula and your washing habits before declaring war on sulfates.

The practical takeaway

My goal with this guide was to gather the useful science on sodium laureth sulfate in one place, so you can stop hunting for the next clever fix and do the simple, effective things your skin actually needs.

That is also why I made the Danish Skin Care Kit: a calm routine built around documented ingredients, and one that has helped more than 100,000 people with problem skin. If even the smallest question is still nagging you, send me an email at info@danishskincare.com.