Cocamidopropyl Betaine vs Sodium Lauryl Sulfate: which is worse?

What is Cocamidopropyl Betaine?

Cocamidopropyl betaine is an amphoteric (zwitterionic) surfactant derived from coconut oil and dimethylaminopropylamine. It serves as both a primary and secondary surfactant and is known for being gentler than traditional sulfate surfactants. It also has antistatic and conditioning properties.

What is Sodium Lauryl Sulfate?

Sodium lauryl sulfate is an anionic surfactant derived from lauryl alcohol (from coconut or palm oil). It is one of the oldest and most-studied cosmetic surfactants, prized for its powerful foaming and degreasing properties. Unlike SLES, it is not ethoxylated.

Documented risks

Cocamidopropyl Betaine: CAPB itself is well-tolerated by most people. However, it was named Allergen of the Year by the American Contact Dermatitis Society in 2004, indicating it can cause contact allergic reactions in a subset of sensitized individuals. The sensitizer is typically not CAPB itself but trace impurities from manufacturing (amidoamine or 3-dimethylaminopropylamine). High-purity CAPB has a very low sensitization rate. It is not a carcinogen or endocrine disruptor. The CIR concluded CAPB is safe for cosmetic use.

Sodium Lauryl Sulfate: SLS is safe at cosmetic use concentrations per the CIR Expert Panel. It is more irritating than SLES to skin and mucous membranes, particularly at concentrations above 2% with prolonged contact; this is why most rinse-off products keep it at 1–2% or opt for SLES. It can disrupt the skin barrier transiently, which is why some people with canker sores or eczema avoid SLS toothpastes and cleansers. It is not carcinogenic, not a hormone disruptor, and is not absorbed systemically in meaningful amounts. It biodegrades rapidly in the environment.