What causes cocamidopropyl betaine allergy?

Cocamidopropyl betaine allergy is usually caused by amidoamine manufacturing residues.

A mild surfactant common in cleansers. The allergy is usually to manufacturing residues — amidoamine and dimethylaminopropylamine — rather than to the surfactant itself.

Information, not medical advice. A suspected contact allergy should be confirmed by a dermatologist through patch testing.