Potassium Myristate

Potassium myristate is a potassium soap/surfactant (fatty acid salt) used primarily for cleansing and emulsification; in typical leave-on or cleansing concentrations it can be distinctly alkaline and disrupt the stratum corneum lipids. Clinically, soap-based surfactants are well known to increase transepidermal water loss and sting/burn in eczema and compromised skin, with higher risk of irritant contact dermatitis compared with milder syndets. Given its cleansing role and barrier-disruptive potential—especially in reactive or eczematous patients—a notable irritancy score is warranted. Safety Notes: Potassium myristate is most commonly used as an anionic soap/surfactant and co-emulsifier; in many leave-on creams/lotions it appears at low levels (~0.1–1%) as a stabilizer/structurant or part of an emulsifier system. In rinse-off cleansing formats (facial cleansers, shaving soaps/creams, and soap-based bars/liquid soaps), consumer products can use much higher levels because it is a primary cleansing surfactant, with high-strength soap-based systems reaching ~10–30% as part of the total fatty-acid soap content. There is no specific EU/FDA maximum concentration limit for potassium myristate itself in cosmetics; practical upper bounds are driven by pH/irritation, bar integrity, and overall surfactant system design.