BACKGROUND: Propylene glycol (PG) is a solvent, vehicle, and humectant being used increasingly in a wide array of personal care products, cosmetics, and topical medicaments. Propylene glycol is a recognized source of both allergic and irritant contact dermatitis. OBJECTIVE: The aim of the study was to report incidence of positive patch tests to PG at Mayo Clinic. METHODS: We retrospectively reviewed records of all patients patch tested to PG from January 1997 to December 2016. RESULTS: A total of 11,738 patients underwent patch testing to 5%, 10%, or 20% PG. Of these, 100 (0.85%) tested positive and 41 (0.35%) had irritant reactions. Patients also tested to a mean of 5.6 concomitant positive allergens. The positive reaction rates were 0%, 0.26%, and 1.86% for 5%, 10%, and 20% PG, respectively, increasing with each concentration increase. The irritant reaction rates were 0.95%, 0.24%, and 0.5% for 5%, 10%, and 20% PG, respectively. CONCLUSIONS: Propylene glycol is common in skin care products and is associated with both allergic and irritant patch test reactions. Increased concentrations were associated with increased reactions.
BACKGROUND:Propylene glycol (PG) is a solvent, vehicle, and humectant being used increasingly in a wide array of personal care products, cosmetics, and topical medicaments. Propylene glycol is a recognized source of both allergic and irritant contact dermatitis. OBJECTIVE: The aim of the study was to report incidence of positive patch tests to PG at Mayo Clinic. METHODS: We retrospectively reviewed records of all patients patch tested to PG from January 1997 to December 2016. RESULTS: A total of 11,738 patients underwent patch testing to 5%, 10%, or 20% PG. Of these, 100 (0.85%) tested positive and 41 (0.35%) had irritant reactions. Patients also tested to a mean of 5.6 concomitant positive allergens. The positive reaction rates were 0%, 0.26%, and 1.86% for 5%, 10%, and 20% PG, respectively, increasing with each concentration increase. The irritant reaction rates were 0.95%, 0.24%, and 0.5% for 5%, 10%, and 20% PG, respectively. CONCLUSIONS:Propylene glycol is common in skin care products and is associated with both allergic and irritant patch test reactions. Increased concentrations were associated with increased reactions.