Nickel is one of the most common causes of contact allergy in the world. The skin reacts to the allergen nickel with redness, blisters and oozing to more serious inflammation. The real allergen is not the metallic nickel, but the nickel ion. This is usually released with relative ease from metallic nickel, nickel-plated surfaces or nickel-containing alloys in contact with sweat, blood or urine or acidic foods.1

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Will The Nickel Allergy Spread To Other Areas?

The rash normally occurs in areas where your skin came in contact with nickel. But the rash can spread into other areas as well, which never came in contact with nickel. The rashes may get red and itchy. The rashes are generally worse in the parts of the skin that is in direct contact with nickel compared to the other areas.2,4

Does Chocolate Contain Nickel?

Some chocolates may contain nickel depending on the cocoa used in making it. If the cocoa is contaminated with nickel, chocolates may have nickel in it. Another source of nickel in chocolate is the oil used as a hardening agent. However, only the presence of nickel in chocolate does not make it harmful. It depends on the nickel concentration.5

Nickel-Related Food Allergy

About two to ten percent of all nickel allergic patients also respond to nickel-containing foods (oral nickel allergy). In the case of oral nickel allergy, unlike an IgE-mediated food allergy, does not involve a protein allergen as a trigger, but a metallic trace element.

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The nickel allergy - like any allergy - persists for a lifetime. So it is not curable, only the symptoms of the allergy can be treated. Infants and babies under the age of 12 months may also develop nickel allergy and contact dermatitis. It is therefore important that contact with nickel is avoided as much as possible during childhood.

Little research has yet been done on the link between nickel sensitization and genetic factors to suggest the possible cause.2

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Symptoms Of The Allergy (Direct Contact)

When your skin comes in contact with objects containing nickel it produces contact dermatitis. This is a noninfectious inflammation of the skin. The symptoms of contact allergy mainly affect your skin:

  • Change of mucosa in your mouth and throat area
  • Erythema
  • Flaking
  • Hives (urticaria)
  • Swelling
  • Weeping bubbles
  • Wheals

All major symptoms are also often accompanied by severe or mild itching.

Affected are body parts that have direct contact with nickel-containing objects. Often these are hands, fingers, navel, ears or wrists. The symptoms develop within a few minutes or days after contact with nickel and last for one to two days or more.

Contact dermatitis can be a heavy burden on the quality of life of the affected person. In the case of repeated contact with nickel (allergen exposure), the allergic reactions become more pronounced, it can lead to a recurrent or even chronic course of eczema. Chronic eczema can then persist even without allergen contact.2

Allergy Symptoms (Eating Food Containing Nickel)

Symptoms caused by eating foods containing nickel are not limited to the skin. There is a wider range of symptoms:

Symptoms of the general condition

  • General malaise
  • Palpitations
  • Migraine
  • Tiredness or
  • Depressive moods

Symptoms of the skin

  • Torn fingertips
  • Blisters between the fingers
  • Dry and chapped skin on hands and feet
  • Chronic eczema (on hand, inner thighs, neck or hairline)
  • Dry flaky skin around the eyes and on the forehead
  • Festering blisters or pustules all over the body3

In some cases, nickel ingested via food is eliminated through your sweat glands and an allergic rash on the skin around the armpits may develop. As all these symptoms can happen due to other conditions as well, it often becomes difficult to find out if nickel is the trigger.

Conclusion

Ingestion, as well as skin contact, can cause nickel allergy in children and adults. The real allergen is not the metallic nickel, but the nickel ion. Several foods containing nickel can cause an allergy. Nickel allergy can spread to other areas as well that had not come in direct contact with the metal. Chocolates may contain nickel if the cocoa or the oil used to make it is contaminated.

References:  

  1. Ahlström MG, Thyssen JP, Wennervaldt M, Menné T, Johansen JD. Nickel allergy and allergic contact dermatitis: a clinical review of immunology, epidemiology, exposure and treatment. Contact dermatitis. 2019.
  2. Lidén C. Metal allergy: nickel. Metal Allergy: Springer; 2018:423-434.
  3. Alhadrami HA, Mbadugha L, Paton GI. Hazard and risk assessment of human exposure to toxic metals using in vitro digestion assay. ChemiCal SpeCiation & BioavailaBility. 2016;28(1-4):78-87.
  4. Tuchman M, Silverberg JI, Jacob SE, Silverberg N. Nickel contact dermatitis in children. Clinics in dermatology. 2015;33(3):320-326.
  5. Kruszewski B, Obiedziński MW, Kowalska J. Nickel, cadmium and lead levels in raw cocoa and processed chocolate mass materials from three different manufacturers. Journal of Food Composition and Analysis. 2018;66:127-135.

Also Read:

Sheetal DeCaria MD

Written, Edited or Reviewed By:

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Last Modified On: August 17, 2019

This article does not provide medical advice. See disclaimer

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