Cetyl Betaine

Cetyl betaine is a zwitterionic (amphoteric) surfactant/conditioning agent used mainly in cleansers and shampoos to improve foam and reduce the harshness of primary detergents, typically at low single-digit percentages. While generally milder than anionic surfactants, betaine-type surfactants can still sting and provoke irritant dermatitis—especially on eczematous or barrier-compromised skin and in leave-on edge cases—so I score it as mild rather than “gentle” for high-sensitivity patients. Safety Notes: Cetyl betaine is an amphoteric surfactant/conditioning agent most often encountered in rinse-off cleansing systems (shampoos, body washes, facial cleansers) where it is used at low levels (~0.1–1%) as a foam/feel modifier alongside primary surfactants, and more commonly ~1–5% as a secondary surfactant to reduce irritation and boost viscosity. In high-mildness or sulfate-free consumer cleansers it can be pushed to ~6–8% as part of the main surfactant blend, while leave-on products typically use it at the low end due to its surfactant nature and potential for tack/irritation at higher levels. No specific EU/FDA maximum is set for this INCI, so observed limits are driven primarily by sensorial/stability constraints and overall surfactant active matter targets rather than regulation.