Overview
Allergic contact dermatitis is a delayed hypersensitivity reaction (the reaction to the allergen occurs 48–72 hours after exposure). The most common allergens causing allergic contact dermatitis appear to be nickel, chromates, rubber chemicals, and neomycin (an antibacterial).
- Nickel is found in jewelry, belt buckles, and metal closures on clothing.
- Chromates are found in shoe leathers.
- Rubber chemicals are found in gloves, balloons, and elastic in garments.
- Neomycin is common in triple antibiotic first aid ointments such as Neosporin® (and generic versions of Neosporin) as well as other combination preparations with other antibacterials and corticosteroids and other topical ointments, creams, and lotions. It may also be found in eye preparations, eardrops, and some vaccines.
- Common allergen-containing products include cosmetics, soaps, dyes, and jewelry.
- The most frequent sensitizers in the general population are fragrance, nickel, neomycin, formaldehyde, lanolin (wool grease found in ointments and cosmetics), and a host of other common environmental chemicals.
- Poison ivy is a frequent cause and is discussed separately.