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.
From the *Department of Internal Medicine, Loma Linda University, CA; †Clinical Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL; and ‡Department of Dermatology, Loma Linda University, CA.
Address reprint requests to Sharon E. Jacob, MD, Department of Dermatology, Loma Linda University, Faculty Medical Offices, 11370, Anderson St, Suite 2600, Loma Linda, CA 92354. E-mail: firstname.lastname@example.org.
S.E.J. is the founder and chief executive officer of Dermatitis Academy, an open-access contact dermatitis learning forum, E-source; served as the coordinating principal investigator on the safety and efficacy of T.R.U.E. Test (Smart Practice, Phoenix, AZ) Panels 1.1, 2.1, and 3.1 in children and adolescents, Pediatric Research Equity Act (PREA-1) trial; and has served as a consultant for Johnson & Johnson. A.S. is the director of the American Contact Dermatitis Society Contact Allergen Management Program database. M.A.M. has no funding or conflicts of interest to declare.