What Is Cocamidopropyl Betaine?

A 2024 safety assessment in Toxicological Research describes cocamidopropyl betaine, or CAPB, as a surfactant derived from coconut oil that is widely used in cosmetics and personal products for purposes such as a surfactant, foam booster, mildness and viscosity control. A 2008 article in the journal Dermatitis explains that it is made by adding coconut fatty acids to DMAPA to form an intermediate compound called amidoamine, which is then combined with monochloroacetic acid to form CAPB.

The 2008 Dermatitis article says recognition of allergy to CAPB-containing products became so prevalent that the American Contact Dermatitis Society named CAPB Contact Allergen of the Year in 2004. It says commercial-grade CAPB is contaminated with the reagents used in its formation and can contain up to 3.0% amidoamine and up to 0.02% DMAPA, and that a majority of patch testing studies have shown that clinical allergy to CAPB-containing products actually reflects allergy to the contaminant DMAPA in most cases. The 2024 Toxicological Research assessment likewise says amidoamine and DMAPA contamination may be responsible for its skin sensitizing potential.

The Cosmetic Ingredient Review says in a final report released April 4, 2014 that it has reviewed the safety of cocamidopropyl betaine and related amidopropyl betaines as used in cosmetics, and that its expert panel concluded these ingredients were safe in cosmetics as long as they are formulated to be non-sensitizing, which may be based on a quantitative risk assessment.