Sodium Lauryl Sulfate

Sodium Lauryl Sulfate is a strong anionic surfactant commonly used in cleansers and toothpastes (often ~0.5–10%) and is a well-established irritant in patch testing and controlled exposure studies, frequently causing barrier disruption, stinging, and eczematous flares. In sensitive, compromised, or atopic skin, even brief or repeated contact can provoke significant irritation due to its lipid/protein denaturing effects and cumulative damage with routine use. Given its consistent use as a positive control for irritation and the high likelihood of reactions in reactive populations, it warrants a very high irritancy score for patient safety. Safety Notes: In commercial skincare, SLS appears at very low levels (~0.05–0.5%) as a minor co-surfactant/foam booster in mild facial cleansers and some rinse-off washes, while many products avoid it entirely in leave-on formats due to irritation potential. Typical mass-market rinse-off cleansers, body washes, and shampoos commonly use ~1–15% SLS (often in blends with other surfactants). The highest consumer-available levels are seen in strong degreasing/clarifying cleansers and cleansing pastes/bars where SLS can reach roughly 20–30% as the primary anionic surfactant (still rinse-off; leave-on products are generally near zero to trace).

Suitability