Contact allergy to nickel: still #1 after all these years.

Nickel is ubiquitous in our daily environment and remains the most common cause of contact allergy worldwide. Regulation of nickel release exists in Europe but unfortunately continues to be absent in the United States. Nickel contact allergy most often is associated with earrings and other jewelry; however, novel exposures to nickel through diet and electronic devices and other materials also occur. Once diagnosed, allergen avoidance is key for improvement of symptoms.