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SODIUM LAURYL SULFATE.

Avoid CAS 151-21-3 / CLEANSING, DENATURANT, FOAMING, SURFACTANT - CLEANSING, SURFACTANT - EMULSIFYING

Sodium Lauryl Sulfate (SLS) is a potent anionic surfactant prized for its exceptional cleansing and foaming capabilities. While effective at impurity removal, its robust action can strip the skin's natural lipids, compromising the skin barrier and leading to dryness, irritation, and potential dysbiosis of the skin's microbiota.

Summary

cleansing denaturant emulsifying foaming surfactant

Science

Mechanism of Action

As a surfactant, Sodium Lauryl Sulfate reduces the surface tension of liquids, enabling the effective mixing of oil and water and facilitating the removal of impurities during cleansing. This mechanism involves stripping the skin of its natural sebum, which often results in dryness and irritation. Concurrently, it disrupts the skin's protective barrier function, leading to increased transepidermal water loss (TEWL) and heightened vulnerability to external irritants.

Research

Clinical Evidence

High confidence
Effective range 0.1–10%
Optimal

N/A

Key findings

  1. 01 An aqueous solution applied under occlusive patch for 24 hours significantly increased skin redness, decreased stratum corneum hydration, impaired skin barrier function, and led to skin bacterial community dysbiosis.
  2. 02 Demonstrated a reduction in healthy skin thickness and an increase in water loss permeability.
  3. 03 Induced a moderate irritant effect in animal studies.
  4. 04 Aqueous solutions were shown to irritate the skin and increase Transepidermal Water Loss (TEWL).
  5. 05 Products kept on the skin for 24 hours may result in skin dehydration and irritation.
  6. 06 Irritation on human skin progressively increased with higher concentrations within this range.

Transparency

Dusting Analysis

Not commonly dusted

Sodium Lauryl Sulfate is a highly functional ingredient serving as a primary surfactant, cleanser, and foaming agent, thus it is not typically 'dusted'. However, its known irritant properties at various concentrations necessitate careful consideration, particularly for leave-on formulations or products for sensitive skin.

The Formula

Formulation

Solubility
Water
Optimal pH 7 – 9
0 7 14

Stability

The irritant potential of SLS can be attenuated in some cosmetic formulations, often by incorporating co-surfactants. The severity of irritation is directly correlated with both its concentration and the duration of skin contact.

Synergies

  • Co-surfactants (to attenuate irritant properties)

Conflicts

  • strong oxidants
  • strong acids
  • conditions where both solute and surfactant are ionized (risk of desolubilization)

Safety

Safety Profile

CIR Status
Safe as used
Max tested
1%
Sensitization risk Low

The Cosmetic Ingredient Review (CIR) Expert Panel considers Sodium Lauryl Sulfate safe for use, recommending that concentrations do not exceed 1% for products intended for prolonged skin contact. Higher concentrations are considered safe for products designed for brief, discontinuous use followed by thorough rinsing. SLS is recognized as a skin and eye irritant, with irritation increasing with concentration, but it is not classified as a sensitizer. It has been noted to cause epidermal changes and contribute to comedone formation. The most recent CIR review in 2025 concluded its safety across a concentration range of 0.008% to 50%. The FDA also regards SLS as safe when used as a food additive.

Your Skin

Skin Compatibility

No Normal
No Dry
No Oily
No Sensitive
Irritancy High
Comedogenicity High

Our Assessment

Verdict

Avoid

Sodium Lauryl Sulfate is a powerful cleansing agent with high irritancy and comedogenicity, making it generally incompatible with all skin types due to its propensity to disrupt the skin barrier and cause dryness.

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