Allergic contact dermatitis is a skin condition where the skin breaks out in a rash following direct contact with an allergen. While the exact cause of allergic contact dermatitis remains unknown, research has shown that the reaction is similar to that of other allergies. The body’s immune system inappropriately views a harmless substance as being harmful and develops an immune response against it. The rash of contact dermatitis appears within hours to days at the site where the skin came in contact with an allergen. The reaction typically resolves within a few days however it may last as long as two to four weeks.