Epidemiology and Co-Reactivity of Novel Surfactant Allergens: A Double-Blind Randomized Controlled Study.

Background: Surfactants are cleansing agents used in products such as shampoos and soaps.

Objectives: The aims of this study were to identify positivity rates to 3 novel amide-containing surfactants (sodium lauroyl sarcosinate, isostearamidopropyl morpholine lactate, and disodium lauroamphodiacetate) and evaluate co-reactivity with other surfactants in patients with known surfactant sensitivity.

Methods: Previously patch-tested, surfactant-positive patients were identified via chart review and invited to participate. Participants were patch tested to screening surfactants (cocamidopropyl betaine, amidoamine, dimethylaminopropylamine, cocamide diethanolamine [DEA], oleamidopropyl dimethylamine, and decyl glucoside), as well as 3 novel surfactants: sodium lauroyl sarcosinate 0.5% and 1.0% aq, isostearamidopropyl morpholine lactate 0.5% and 1.0% aq, disodium lauroamphodiacetate 1.0 and 2.0% aq, and a hypoallergenic liquid cleanser (tested semiopen). Participants and clinicians were blinded. The order of tested allergens was randomized.

Results: Forty-seven participants completed the study. Excluding doubtful reactions, positive reactions were most common to oleamidopropyl dimethylamine (34%) and dimethylaminopropylamine (34%), followed by isostearamidopropyl morpholine lactate (23%). Reactivity was not associated with history of childhood eczema. Co-reactivity was high among oleamidopropyl dimethylamine, dimethylaminopropylamine, cocamidopropyl betaine, amidoamine, and isostearamidopropyl morpholine lactate. None of the participants who reacted to cocamide DEA reacted to an additional surfactant.

Conclusions: Isostearamidopropyl morpholine lactate may be an important emerging allergen with sensitivity rates comparable with those of oleamidopropyl dimethylamine and dimethylaminopropylamine. Co-reactivity among surfactants was frequent except for cocamide DEA.