Background. Contact allergy to cocamidopropyl betaine has been attributed to its impurities dimethylaminopropylamine and cocamidopropyl dimethylamine.
Objectives. To describe patients with positive patch test reactions to cocamidopropyl betaine‐related compounds in an occupational dermatology clinic.
Methods. We reviewed the 2002–2009 patch test records at the Finnish Institute of Occupational Health for allergic reactions to cocamidopropyl betaine, dimethylaminopropylamine, cocamidopropyl dimethylamine, and oleamidopropyl dimethylamine.
Results. Irritant reactions to at least one of the test substances were seen in 39% of the 1092 patients tested. Fifteen (1.3%) patients showed allergic reactions: 13 to cocamidopropyl dimethylamine, 11 to dimethylaminopropylamine, 8 to oleamidopropyl dimethylamine, and 2 to cocamidopropyl betaine. Concomitant reactions to cocamidopropyl dimethylamine, dimethylaminopropylamine and oleamidopropyl dimethylamine were common. Ten of the 15 patients were diagnosed with occupational allergic contact dermatitis caused by cocamidopropyl betaine‐related compounds. The sources of occupational exposure included hair care products, hair colours, perm wave solutions, and liquid soaps. Multiple contact allergies and exposure to several irritant factors were common, and all patients had hand eczema.
Conclusions. Patch test reactions to cocamidopropyl betaine‐related compounds are difficult to interpret, owing to extremely common irritant reactions. Cocamidopropyl betaine itself is probably not an allergen. Occupational allergic contact dermatitis caused by cocamidopropyl betaine‐related compounds is relatively rare and, unlike non‐occupational cocamidopropyl betaine‐related allergy, typically manifests as hand dermatitis.