The American Contact Dermatitis Society (ACDS) selected sulfites as the 2024 Allergen of the Year. These common and potentially allergenic ingredients are used as preservatives and antioxidants in a variety of foods, beverages, medications, and personal care products. In this article, we review common sources of sulfite exposure, clinical manifestations of allergic contact dermatitis (ACD) to sulfites, and patch testing considerations for this emerging allergen.