Carrageenan

Carrageenan is a sulfated polysaccharide used primarily as a thickener/gel former in leave-on and rinse-off products, typically at low concentrations (about 0.1–2%). In human topical use it is generally well tolerated and not a common irritant or sensitizer in patch testing, but as a high–molecular weight film former it can occasionally contribute to stinging/tight-feel in very reactive or barrier-impaired skin when layered with other potential irritants. Given its low intrinsic reactivity yet non-zero risk in compromised eczema-prone populations, it fits best as very gentle rather than completely inert. Safety Notes: In commercial skincare, carrageenan is most commonly used as a secondary thickener/stabilizer in rinse-off cleansers, shower products, and some leave-on gels/lotions at very low levels (~0.01–0.2%) to support viscosity and suspension. Higher concentrations are found in consumer-available gel masks, peel-off/film-forming masks, and thixotropic gel textures where carrageenan functions as a primary gellant, with real-world formulas reaching ~1–3% depending on carrageenan type/blend and the presence of other gums/salts. Above ~3% is uncommon in OTC cosmetics because gels can become overly rigid/stringy and harder to process/package, so most market products cap around this level.

Suitability