Allergenicity and cross-reactivity of coconut oil derivatives: A double-blind randomized controlled pilot study

Background: Counseling of patients with cocamidopropyl betaine (CAPB) allergy is difficult because the cross-reactivity of CAPB with other coconut-derived surfactants, coconut oil, and coconut fatty acids is largely unknown. Objective: To provide pilot data regarding the cross-reactivity and allergenicity of surfactants derived from coconut oil. Methods: A randomized double-blind controlled pilot study of 10 control patients and 12 patients previously found to be allergic to CAPB. Eleven coconut-derived surfactants, as well as coconut oil and lauric acid, were applied in random order according to standardized patch-test procedures with readings at 48 and 92 hours. The primary outcome measure was the frequency of positive patch-test reactions to each allergen. Results: Only 3 of the 12 patients with previous reactions to CAPB reacted on retesting, and all of these reactions were doubtful. Fifty-nine percent of the study patients had reactions to triethanolamine polyethylene glycol-3 (TEA-PEG-3) cocamide sulfate as compared to none of the controls (p = .005). Conclusions: Reactions to CAPB were only 25% reproducible. These results substantiate previous experience that doubtful and mild reactions to CAPB may represent irritant reactions as opposed to true allergic reactions. TEA-PEG-3 cocamide sulfate was the only agent that had a statistically significant higher rate of reactions in the study group as compared to the control group.