Oleth-20

Oleth-20 is an ethoxylated fatty alcohol surfactant/solubilizer used at low-to-moderate levels to help disperse oils and improve cleansing or emulsification. As a surfactant, it can disrupt the stratum corneum lipids and increase transepidermal water loss, so stinging or irritation is possible in eczema-prone or barrier-compromised skin, especially in leave-on products or when layered with other irritants. It is not typically a strong sensitizer, but given its functional class and real-world use in multi-ingredient routines, I rate it as mildly irritating. Safety Notes: Oleth-20 (PEG-20 oleyl ether) is used in consumer skincare primarily as a solubilizer/surfactant/emulsifier and appears at very low levels (~0.1–1%) in leave-on lotions, toners, micellar-type waters, and serums to help solubilize fragrance/oils and stabilize emulsions. In rinse-off cleansers and specialty solubilizing bases (cleansing oils, makeup removers, self-emulsifying systems), levels commonly rise into the mid-single digits, and high-surfactant concentrate/solubilizer-heavy OTC products can reach ~10–15% to achieve clarity and robust oil solubilization. No specific FDA/EU maximum concentration is set for Oleth-20 in cosmetics; practical limits are driven by irritation potential, clarity, viscosity, and phase behavior, with higher levels more typical of rinse-off than leave-on.