Gentle surfactant used in skincare products, almost always as a secondary cleansing agent and lather booster. When used alone as the sole cleansing agent, it is too mild to clean adult skin and hair.
Cocamidopropyl betaine may be plant-derived or synthetic, with either form considered safe for use in cosmetic products. It is considered low risk for sensitizing skin, although impurities resulting from poor manufacturing can increase the risk.
References for this information:
International Journal of Toxicology, July-August 2012, Supplement, pages 77S-111S
Contact Dermatitis, May 2012, pages 286-292 ; April 2011, pages 203-211 ; and May-June 2008, pages 157-160