Propylene Glycol in Contact Dermatitis: A Systematic Review.

Propylene glycol (PG), an emollient and emulsifier found in cosmetics, medications, and food, has been granted the dubious honor of being named the American Contact Dermatitis Society's Allergen of the Year for 2018. Contact, systemic, and irritant cutaneous reactions have been documented for PG, which has become an increasingly common ingredient. Propylene glycol is as contentious as it is ubiquitous because it acts as both a weak sensitizer and an irritant, confounding the results of positive patch tests. This review serves to delve into what we know about PG from previous reports and studies so that providers will have a better understanding of PG contact dermatitis.