What is Nickel Allergy?
A nickel allergy is a sensitization of the immune system to the metallic element nickel. Nickel metal is normally harmless, but in a nickel allergy, the immune system overreacts when the skin touches objects containing nickel. The resulting symptoms are due to an allergic reaction.
Nickel allergy is present in about 8 to 9% of the overall population (Pontoppidan Thyssen et al. 2007), making it one of the most common of all allergies.
Symptoms of Nickel Allergy
Nickel allergy causes dermatitis, an inflammation of the skin, within 12 to 48 hours of contact with the metal. Contact dermatitis can last several weeks and may include rash, hives itching, blisters, skin dryness, and even blisters that may drain fluid. The symptoms are most likely to occur where the nickel touches the skin, but may occur elsewhere on the body as well (Mayo Clinic 2007).
Nickel allergy symptoms can be triggered by contact with the metal itself, either pure metal or in an alloy, or with compounds containing nickel (nickel salts). Sweat causes nickel ions to dissolve, triggering the allergic reaction (Conard 2007).
Causes of Nickel Allergy
Nickel allergy is closely associated with female gender, early exposure to the metal nickel, and ear piercing early in life (Pontoppidan Thyssen et al. 2007). These correlations are due to the fact that many earrings contain nickel metal. Nickel allergy is more prevalent in females because girls and women have their ears pierced more often than boys and men do. Ear piercing early in life means more potential exposure to nickel metal in earrings and therefore more chances to develop the allergy.
Nickel allergy is a little unusual among allergies because it is triggered by a metallic element instead of a protein or other large molecule. Nickel can trigger immune reactions both by binding to certain proteins in the skin, making a metal-protein complex that causes an immune reaction, and by binding to certain immune system compounds that then trigger an overreaction of T cells (Czarnobilska et al. 2007).
Prevention and Treatment of Nickel Allergy
To avoid nickel allergy symptoms, it is not necessary to avoid ear piercing or to stop wearing pierced jewelry. Many earrings and other jewelry available today are “hypoallergenic,” meaning they are made without nickel and are unlikely to cause allergic reactions. To reduce the chance of developing a nickel allergy, jewelry wearers should use only hypoallergenic earrings or other jewelry, especially if the person has a history of allergies or if there is a family history of nickel allergy.
Nickel metal is found in other objects besides jewelry. Contact with wet skin is most likely to cause a reaction. People with nickel allergy should be careful around the following (Mayo Clinic 2008):
- All metal jewelry, including watchbands and metal hair accessories such as bobby pins
- Clothing fasteners, including jeans snaps and bra hooks; belt buckles and suspender clips
- Eyeglass frames
- Coins (both U.S. and Canadian nickel coins contain nickel metal)
- Stainless steel kitchen utensils
- Paper clips
- Pens with metal bits
- Metallic tools
- Any object made with stainless steel, an alloy that contains nickel
- B. R. Conard. “Nickel Allergic Contact Dermatitis.” 2007; published online by the Nickel Institute.
- E. Czarnobilska, K. Obtulowicz, K. Wsołek, J. Pietowska, and R. Spiewak. “Mechanisms of nickel allergy .” Przegla̧d Lekarski (Medical Review; Polish) 2007;64(7-8):502-5.
- Mayo Clinic staff. “Nickel allergy .” 2008; MayoClinic.com.
- Jacob Pontoppidan Thyssen, Allan Linneberg, Torkil Menné, and Jeanne Duus Johansen. “The epidemiology of contact allergy in the general population – prevalence and main findings .” Contact Dermatitis Aug 2007;57(5):287-299.