Sodium Lauryl Sulfate

A strong surfactant that creates a rich lather but can be stripping and irritating for some. Sodium Lauryl Sulfate (SLS) is an anionic surfactant that functions by significantly reducing surface tension. On the skin, it interacts with the lipid matrix and proteins of the stratum corneum. It solubilizes intercellular lipids and denatures keratin, leading to a disruption of the skin barrier function. This disruption increases transepidermal water loss (TEWL) and enhances the penetration of other substances, contributing to its cleansing action and potential for irritation.

The CIR Expert Panel has deemed Sodium Lauryl Sulfate safe in cosmetic formulations when used in rinse-off products and in leave-on products at concentrations up to 1%. It is a known skin irritant, particularly at higher concentrations or with prolonged exposure, and can cause dryness, redness, and itching, especially in individuals with sensitive skin or a compromised skin barrier, but is not considered a sensitizer.

Look for products with 1-50% (often 1-10% in leave-on or sensitive skin rinse-off products; up to 30% or more in strong foaming cleansers like shampoos). for clinical efficacy.