What Are SLS and SLES? Understanding These Common Cleansing Ingredients

What Are SLS and SLES?

If you've ever looked at the ingredients on a shampoo or body wash, you've probably seen Sodium Lauryl Sulfate (SLS) or Sodium Laureth Sulfate (SLES).

These ingredients have been used in personal care products for decades because they are excellent cleansers and create the rich foam many people associate with being "clean."

However, in recent years they've become one of the most discussed ingredients in hair care and skincare.

So what exactly are they, and should you avoid them?

What Is Sodium Lauryl Sulfate (SLS)?

Sodium Lauryl Sulfate is a surfactant.

A surfactant helps water mix with oils, dirt and grease so they can be rinsed away.

It is also responsible for creating the rich lather found in many shampoos, body washes, facial cleansers and household cleaning products.

What Is Sodium Laureth Sulfate (SLES)?

Sodium Laureth Sulfate performs a similar job to SLS.

The difference is that SLES goes through an additional manufacturing step called ethoxylation, which generally makes it milder than SLS while still producing a rich foam.

Both ingredients are effective cleansers.

Where Do They Come From?

SLS and SLES are commonly manufactured using fatty alcohols derived from plant oils such as:

  • Coconut oil
  • Palm kernel oil

These plant-derived raw materials are then processed into cleansing ingredients suitable for cosmetic products.

Although they originate from plant oils, the finished ingredients are highly refined and are considered synthetic cosmetic ingredients.

Why Are SLS and SLES Used?

Manufacturers choose these ingredients because they:

  • Produce lots of foam.
  • Clean effectively.
  • Remove oils and dirt.
  • Work well in hard water.
  • Are cost-effective.
  • Help products rinse away easily.

They've become some of the most widely used cleansing ingredients in the world.

Why Do Some People Choose Sulfate-Free Products?

While SLS and SLES are effective cleansers, they aren't the right choice for everyone.

Some people find products containing strong sulfates leave their:

  • Hair feeling dry.
  • Skin feeling tight.
  • Scalp feeling sensitive.

This is more likely in people who already have dry or sensitive skin, or who wash their hair frequently.

Not everyone experiences these effects, many people use sulfate-containing products without any problems.

Are SLS and SLES Dangerous?

For most people, cosmetic products containing SLS or SLES are considered safe when used as intended.

The concern is generally not that they are inherently dangerous, but that they may be too cleansing for some individuals, particularly those with dry, damaged or sensitive skin and hair.

Like many cosmetic ingredients, whether they are suitable depends on the individual and the overall product formulation.

Why Are They Used in Shampoo?

Sulfates are excellent at removing:

  • Oil
  • Sweat
  • Dirt
  • Styling products
  • Silicone build-up

This makes them particularly useful in clarifying shampoos and products designed for deep cleansing.

Why Doesn't Healing Season Use SLS or SLES?

At Healing Season, we prefer to formulate products using carefully selected ingredients that align with our approach to traditional hair care.

Rather than relying on strong foaming detergents, we focus on simple ingredients chosen to gently cleanse and condition while leaving hair feeling clean and manageable.

Our shampoo and conditioner bars are designed to provide an effective cleansing routine without using SLS or SLES.

Frequently Asked Questions

Are SLS and SLES the same ingredient?

No.

They are closely related, but SLES undergoes an additional manufacturing process that generally makes it milder than SLS.

Why do sulfates create so much foam?

Sulfates are highly effective surfactants, meaning they help water lift away oils and dirt while creating a rich lather.

Does more foam mean better cleaning?

Not necessarily.

Foam helps spread a product through the hair, but the amount of lather doesn't always reflect how well a product cleans.

Are sulfate-free shampoos better?

It depends on your hair type and personal preference.

Some people prefer sulfate-free products because they find them gentler on their hair or scalp, while others are happy using products that contain sulfates.

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