What is it?
A cleansing and foam-boosting ingredient made from coconut fatty acids. Its molecule carries both a positive and a negative charge, which puts it in the family of amphoteric surfactants called betaines. It is one of the most widely used cleansers in shampoos, conditioners, body washes, facial cleansers, liquid soaps and bath products, where it cleanses, builds foam, thickens the formula and conditions hair. It is also used in household cleaning products such as laundry detergents and dishwashing liquids.
Key information
- The CIR Expert Panel concluded that cocamidopropyl betaine is safe in cosmetics as long as products are formulated to be non-sensitizing, which may be based on a quantitative risk assessment.
- It is a known cause of allergic skin reactions, which the CIR attributes mainly to two manufacturing leftovers, DMAPA and amidoamine.
- It is not a sulfate, is not ethoxylated and, unlike cocamide DEA, is not made with diethanolamine.
More information
Cocamidopropyl betaine (CAPB) is made in two steps. Coconut fatty acids are reacted with 3-dimethylaminopropylamine (DMAPA) to form an intermediate called amidoamine, which is then reacted with sodium monochloroacetate. Traces of DMAPA and amidoamine can remain in the finished ingredient. The Cosmetic Ingredient Review (CIR) reported it in 2,743 products, at 0.005 to 11 percent.
CAPB has a well-documented allergy history. It was named the contact allergen of the year for 2004, and in one clinic study 12 of 210 patients with suspected cosmetic allergies (5.7 percent) reacted to it on patch testing. Researchers have found that one or both impurities, DMAPA and amidoamine, may be responsible. The CIR Expert Panel reviewed CAPB with 30 related amidopropyl betaines and found no other significant toxicity: tests for genetic damage were negative, and 13 studies on normal human skin at use concentrations produced no allergic reactions. A risk assessment found that DMAPA at 0.01 percent in the raw material would not cause allergy in finished products, while amidoamine at 0.5 percent might in some. The Panel concluded these ingredients are safe as long as products are formulated to be non-sensitizing, and urged manufacturers to keep both impurities low. In 2014 it reached a similar conclusion for the amidoamines themselves.
CAPB is not a sulfate, is not ethoxylated and, unlike cocamide DEA, is not made with diethanolamine. Because it contains an amide group and may carry amine impurities, the Panel advises that it not be used in products containing N-nitrosating agents, which can form nitrosamines; it gives the same advice for cocamidopropyl hydroxysultaine. People diagnosed with an allergy to CAPB or its impurities should know that related ingredients made the same way, such as lauramidopropyl betaine, can carry the same impurities.
Sources: Cosmetic Ingredient Review: Final amended safety assessment of cocamidopropyl betaine and related amidopropyl betaines (December 2010 panel materials); Cosmetic Ingredient Review: Safety assessment of fatty acid amidopropyl dimethylamines (2014); Cosmetic Ingredient Review: Quick reference table, safe-with-qualifications findings (2020)
