Why Is Sodium Lauryl Sulfate (SLS) In So Many Products Despite Its Bad Reputation?

Producing liquid soap is actually a fairly drawn out process requiring many different steps. Most soap companies from designer brands to artisan soap makers don’t have the equipment, capacity or know-how to make liquid soap on a scale that will make it cheap enough to distribute and sell for profit.

Instead, they make products their own by creating a unique scent which is then added to a mass produced liquid like SLS, SLES or a more natural alternative before bottling. SLS is one of the more common liquid soaps used because it is clear and odourless so more easily coloured and scented to make a new “unique” liquid soap. It is usually derived from palm oil which adds to its cost-effectiveness.

Whilst SLS is an effective detergent, it can also be a skin irritant. As HealthLine reports:

“SLS and SLES can irritate eyes, skin, and lungs, especially with long-term use. SLES may also be contaminated with a substance called 1,4-dioxane, which is known to cause cancer in laboratory animals. This contamination occurs during the manufacturing process.”


SLS is also often added to toothpaste to act as a foaming agent. A Norwegian study in 1994 revealed that this almost tripled the rate of mouth ulcers for those susceptible. A systematic review in 2019 concluded that “SLS‐free dentifrice, when compared to SLS‐containing statistically significantly, reduced the number of ulcers, duration of ulcer, number of episodes, and ulcer pain”. So if you’re experiencing an increase in mouth ulcers, make sure to check the ingredients list of your toothpaste!

To answer the original question, SLS is so common for a number reasons:

  • It is clear and odourless, so can be added to many different types of products.
  • It can be derived from palm oil and petroleum, making it one of the most cost effective surfactants.
  • Its foaming properties make it popular with consumers, who often associate this with premium products.

I hope this article has been helpful! If you would like to see sulfate-free product recommendations, click here.

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