Ammonium Lauryl Sulfate vs Cocamidopropyl Betaine: which is worse?

What is Ammonium Lauryl Sulfate?

Ammonium lauryl sulfate is an anionic surfactant analogous to SLS but with an ammonium cation. It provides strong foaming and cleansing. It is slightly more water-soluble than SLS.

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.

Documented risks

Ammonium Lauryl Sulfate: ALS is slightly more irritating than ALES and comparable to SLS at equivalent concentrations. At typical shampoo concentrations (2–10%), it is considered safe by the CIR. It is not carcinogenic, not a hormone disruptor, and does not accumulate in body tissues. Prolonged skin contact at high concentrations can cause irritation; this is not a concern in rinse-off applications.

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.