INCI name

Sodium Lauryl Sulfate

Also listed as: SLS, sodium dodecyl sulfate

Sodium lauryl sulfate is a strong, foaming surfactant. It is a common cleaning agent in toothpastes, dish soaps and some shampoos. It removes oil well, which is why it also appears in studio "makeup remover" and household cleaners.

SLS is not the same as sodium laureth sulfate (SLES). The extra "eth" in SLES means the molecule has been ethoxylated, which usually makes it milder. They are easy to mix up on a label.

SLS can irritate skin and eyes, especially in leave-on use or at high wash-off levels, and it is a frequent culprit when a toothpaste stings mouth ulcers. Many "SLS-free" toothpastes exist for that reason.

Where it turns up

Toothpaste, shampoos, body washes, household cleaners and some bubble-bath products.

Sensitivities

A common irritant, especially on damaged skin or in the mouth. That is irritation more often than true allergy, though allergy can occur.

Vegan or animal-derived

Typically synthetic or plant-lauryl. Usually vegan.

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