What it is
Sodium Lauryl Sulfate is a strong anionic surfactant valued for its ability to lower surface tension, generate dense foam, and remove oils and soil. In sunscreens it appears mainly as a processing aid or secondary surfactant that helps disperse and emulsify ingredients rather than as a primary cleanser. It is also a common ingredient in shampoos, body washes, and toothpastes.
Safety & warnings
Sodium lauryl sulfate is a recognized skin and eye irritant at higher concentrations and is frequently used as a positive control in patch-test irritation studies, which can give an exaggerated impression of its risk at the low, brief-contact, or rinse-off levels typical of finished products. It is not classified as a contact allergen; the main concern is irritation and drying with prolonged or high-level exposure, more likely on compromised or sensitive skin.
Origin & sourcing
Synthetic surfactant, manufactured by sulfation of lauryl alcohol followed by neutralization with sodium. The starting lauryl alcohol can be sourced from petrochemicals or from plant oils such as coconut or palm.
Questions everyone asks
Is sodium lauryl sulfate the same as SLES?
No. SLS is sodium lauryl sulfate; SLES is sodium laureth sulfate, an ethoxylated relative that is generally milder. They are distinct ingredients.
Why is it in a leave-on sunscreen?
In a sunscreen it usually serves as a minor surfactant or emulsifier that helps blend and stabilize the formula, rather than as a foaming cleanser.