rest of their life, and the symptoms will reappear when in contact with the allergen. Cause Common allergens implicated include the following: Bacitracin – topical antibiotic found by itself, or as Polysporin or Triple Antibiotic Balsam of Peru (Myroxylon pereirae) – used in food and drink for flavoring, in perfumes and toiletries for fragrance, and in medicine and pharmaceutical items for healing properties; derived from tree resin. It may also be a component of artificial vanilla and/or cinnamon flavorings. Chromium – used in the tanning of leather. Also a component of uncured cement/mortar, facial cosmetics and some bar soaps. Cobalt chloride – metal found in medical products; hair dye; antiperspirant; metal-plated objects such as snaps, buttons or tools; and in cobalt blue pigment Colophony (Rosin) – rosin, sap or sawdust typically from spruce or fir trees Formaldehyde – preservative with multiple uses, e.g., in paper products, paints, medications, household cleaners, cosmetic products, and fabric finishes. Often released into products by the use of formaldehyde releasers such as imidazolidinyl urea, diazolidinyl urea, Quaternium-15, DMDM Hydantoin, and 2-bromo-2-nitropropane-1,3-diol. Fragrance mix – group of the eight most common fragrance allergens found in foods, cosmetic products, insecticides, antiseptics, soaps, perfumes, and dental products Gold (gold sodium thiosulfate) – precious metal and compound often found in jewelry and dental materials Isothiazolinones – preservatives used in many personal care, household, and commercial products. Mercaptobenzothiazole – in rubber products, notably shoes, gloves, and car tires. Neomycin – topical antibiotic common in first aid creams and ointments, cosmetics, deodorant, soap, and pet food. Found by itself, or in Neosporin or Triple Antibiotic Nickel (nickel sulfate hexahydrate) – has been recognized as a significant cause of allergy. This metal is frequently encountered in stainless steel cookware, jewelry and clasps or buttons on clothing. Current estimates gauge are that roughly 2.5 million US adults and 250,000 children suffer from nickel allergy, which costs an estimated $5.7 billion per year for treatment of symptoms. A significant portion of nickel allergy is preventable. p-Phenylenediamine (PPD) - although it's mainly used as a component of engineering polymers and composites like kevlar, it is also an ingredient in hair dyes which once sensitized to, becomes lifelong. One can develop active sensitization to products, including but not limited to black clothing, various inks, hair dye, dyed fur, dyed leather, and certain photographic products. Photographic developers, especially those containing metol Quaternium-15 – preservative in cosmetic products