Many people are allergic to specific metals, and often times
staining of the skin is thought to be a sign. However, discoloration is caused
by the reaction of certain metals against skin, in particular oxidation of the
metal from perspiration. Real metal allergies will cause the skin to itch and
turn red, and can sometimes leave a rash. Any part of the body can be affected
by a jewelry allergy—a rash on the neck, itchy earlobes, red marks where
jewelry has touched, swelling, or blisters—are all signs indicating an allergy
to metal.