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.Cutis.2021;107:12-15. Nickel is unrivaled as the most common cause of contact allergy worldwide.1 Nickel is commonly used as a hardening agent in metal products, and complete avoidance is challenging due to numerous potential exposures (eg, direct contact, airborne, dietary, medical implantation).Allergic contact dermatitis to nickel (Ni-ACD) can lead to decreased quality of life, inability to work, and considerable health care expenses.1 Here, we review the epidemiology of nickel allergy, regulation of nickel in the United States and Europe, common clinical presentations, and pearls on avoidance. EpidemiologyNickel continues to be the most common cause of contact allergy worldwide.Data from the 2015-2016 North American Contact Dermatitis Group patch test cycle (N=5597) showed nickel sulfate to be positive in 17.5% of patients patch tested to nickel. 2 The prevalence of nickel allergy has been relatively stable in North America since 2005 (Figure 1).Although Ni-ACD historically was identified as an occupational disease of the hands in male nickel platers, the epidemiology of nickel allergy has shifted. 1 Today, most cases are nonoccupational and affect women more often than men, 3 in part due to improved industrial hygiene, pervasive incorporation of nickel in consumer items, and differences in cultural practices such as piercings.1,3 Piercings in particular have been implicated as important sources of nickel exposure, as this practice disrupts normal skin barrier function and is a potentially sensitizing event.Multiple studies including a large-scale epidemiologic analysis from 2017 have found piercings to be associated with an increased frequency of Ni-ACD (24.4% with piercing vs 9.6% without piercing).Interestingly, the degree of nickel sensitivity also was found to increase with the number of piercings (14.3% with 1 piercing vs 34.0% with ≥5 piercings).4 Regulation Nickel content has been regulated in parts of the European Union (EU) since the 1990s, but regulation in the