CD06 Periorbital dermatitis associated with 3-(dimethylamino)-1-propylamine: an 11-patient case series

Abstract

3-(Dimethylamino)-1-propylamine (DMPA) is a chemical found in cosmetics, shampoos and liquid soaps, and is also used as a hardener in epoxy resins and in the manufacture of dyes, fuels and pesticides. It is most commonly encountered as a manufacturing impurity of cocamidopropyl betaine (CAPB), a widely used surfactant in personal care products. Although awareness of CAPB-associated allergy has increased, DMPA-related dermatitis remains under-recognized. A review was carried out to characterize the clinical presentation of DMPA allergy and its relationship to CAPB in a tertiary patch testing cohort. A retrospective review of a tertiary patch testing database was conducted between January 2018 and January 2026. During this period, 1843 patients underwent patch testing with the cosmetic series/BSCA facial series. Patients demonstrating a patch test-positive response to DMPA were identified, and clinical features and relevant exposures were reviewed. Eleven patients (aged 21–70 years; 73% female) were identified with DMPA allergy, representing 0.6% of those tested to the cosmetic series. All patients presented with facial dermatitis, with a marked predilection for the periorbital region. Common features included eyelid erythema, scaling, pruritus and intermittent oedema with extension to the scalp, neck, ears and upper chest. Ten patients demonstrated a patch test-positive response to DMPA in the cosmetic series, while one patient tested positive to DMPA in both the cosmetic and epoxy resin series. While most patients reported exposure to several CAPB-containing personal care products, none of the patients on our database were concomitantly positive to CAPB and DMPA. Only one patient was positive to CAPB over the 9-year period. DMPA allergy presents with a distinctive periorbital-predominant facial dermatitis. The lack of concurrent CAPB positivity in this cohort supports DMPA as an independent allergen and highlights the importance of targeted testing for DMPA in patients with facial eczema.