Nickel Allergy and Allergic Contact Dermatitis

Epidemiology#

Prevalence: 8-19% of adults, 8-10% of children in Europe.^{[1]Nickel Allergy and Allergic Contact Dermatitis: A Clinical ReviewAhlström MG, Thyssen JP, Wennervaldt M et al. · 2019Open reference 1 ↓} Strong female predominance: 4-10x higher in women (14-20% women vs. 2-4% men in US).^{[2]Nickel contact dermatitis in childrenTuchman M, Silverberg JI, Jacob SE et al. · 2015Open reference 2 ↓} Higher in dermatitis patients: 12-25% adults, 5-30% children.

Prevalence declining in some European countries following EU Nickel Directive (1994), but new exposure sources (electronics) keep rates high.

Nickel Allergic Contact Mucositis (Ni ACM)#

Nickel can also cause intestinal mucosal Metal-Driven Inflammation—a Type IV immune response in the gut.^{[3]Beneficial Effects of a Low-Nickel Diet on Relapsing IBS-Like and Extraintestinal Symptoms of Celiac Patients during a Proper Gluten-Free DietBorghini R, De Amicis N, Bella A et al. · 2020Open reference 3 ↓} Causes IBS-like symptoms: abdominal pain, bloating, nausea, loose stools. Also extraintestinal symptoms: dermatitis, headache, fatigue, joint pain.

Prevalence may exceed 30% by epicutaneous patch test. Diagnosed via nickel (Ni) oral mucosa patch test (omPT). Part of "systemic nickel allergy syndrome" (SNAS).

Dietary Nickel as Trigger#

Dietary nickel can trigger systemic reactions in sensitized individuals.^{[4]Dietary Nickel as a Cause of Systemic Contact DermatitisZirwas MJ, Molenda MA · 2009Open reference 4 ↓} Dose-response: 0.3mg oral NiSO₄ caused reactions in 40% of sensitized subjects; 4mg in 70%. A normal daily diet can easily contain >0.58mg nickel.

Celiac disease patients on gluten-free diets may be at special risk because GF foods (corn, legumes, buckwheat) are high in nickel.^{[3]Beneficial Effects of a Low-Nickel Diet on Relapsing IBS-Like and Extraintestinal Symptoms of Celiac Patients during a Proper Gluten-Free DietBorghini R, De Amicis N, Bella A et al. · 2020Open reference 3 ↓}

Regulation#

EU Nickel Directive (1994): limited nickel release from items in prolonged skin contact to <0.5 μg/cm²/week. Extended to piercings (2004) and further under REACH regulation. Led to measurable reduction in sensitization rates in European countries.

No equivalent regulation in US, Asia, or most of the world.

Diagnosis and Treatment#

Patch testing: 5% nickel sulfate in petrolatum (gold standard). DMG spot test: dimethylglyoxime cotton swab test for screening items—turns pink if nickel release >0.5 μg/cm²/week.

Low-nickel diet: effective for systemic symptoms. Avoid whole grains, legumes, nuts, chocolate, canned foods. Vitamin C and iron reduce absorption.^{[4]Dietary Nickel as a Cause of Systemic Contact DermatitisZirwas MJ, Molenda MA · 2009Open reference 4 ↓}

Disulfiram: nickel chelator, useful adjunct but hepatotoxicity risk. Topical treatment: corticosteroids, calcineurin inhibitors.