Nickel allergy is an inappropriate reaction of the immune system to the substance nickel. It is one of the most common forms of allergic contact dermatitis (inflammation that occurs when the skin’s surface comes directly into contact with a substance that triggers an allergic reaction). The allergy usually occurs when skin comes into contact with items containing nickel (e.g., coins, jewelry). People become sensitized (made sensitive) to nickel after having a long period of contact with it. Skin piercing is particularly notorious for allowing nickel to seep into the bloodstream and sensitize an individual.

Traditionally, nickel allergy has primarily affected women because they have worn more jewelry than men. However, an increasing percentage of men now get piercings or wear jewelry. As a result, nickel allergy is occurring in greater numbers of men than ever before.

Preventing symptoms from appearing is difficult once an allergy to nickel has developed. Desensitization techniques, such as allergy shots (treatment in which increasing doses of an allergy-causing substance are injected into a patient over a period of time), are not effective, so avoidance is the only defense. Because nickel is found in so many items, people with this allergy may be advised to buy kits that test products for nickel content.

Experts disagree on whether or not those with nickel allergies need to avoid foods that contain trace amounts of nickel. It is possible that some physicians will recommend a patient abstain from consuming dietary nickel for a period of time to see whether or not this improves symptoms.