When the skin comes in contact with an allergen, a substance that causes an allergic reaction, itching and blistering often occur. Poison ivy, poison oak and poison sumac are the most common causes of allergic reactions. But other common causes of allergic contact dermatitis include metals, insect bites, rubber, dyes, cosmetics, preservatives, fabric softeners and fragrances. While there is no cure for atopic dermatitis, most cases can be controlled with proper treatment. The goals of treatment are to remove the cause of the allergic reaction, reduce inflammation and the risk of infection, and minimize the itch associated with the rash.