The symptoms of a nickel allergy fall under the category of allergic contact dermatitis. If you're allergic to nickel and it touches your skin, your immune system responds by creating an itchy rash. While symptoms can appear as soon as a few hours after you touch nickel, it can take a day or two until they show up. You might break out in a bumpy, itchy rash. Your skin can turn red, and dry patches might develop that look like you were burned. In some cases, you might develop weepy blisters. Normally, the rash is confined to the area where nickel touched you, so if the culprit was a piece of jewelry, your rash will be exactly where the metal touched you. However, in some cases the rash can spread. Sweating can exacerbate the symptoms, which can last up to four weeks. A nickel allergy rash can be treated with a topical corticosteroid cream until it goes away.