Systemic Contact Dermatitis to Metals
Systemic contact dermatitis (SCD) is a subset of allergic contact dermatitis (ACD). SCD is characterized by developing symptoms, most commonly skin rashes, from exposures to an allergen by various routes, not limited to physical contact. Ingesting, infusing and inhaling are other ways in which we are exposed to allergens. Individuals with SCD can experience symptoms, such as a relapse in eczema, when exposed to allergens via any route.
Nickel, cobalt and chromium are common metals found in our diet. Some individuals with ACD to nickel, cobalt or chromium may react to eating food that contain these metals. There is a substantial body of evidence supporting dietary nickel's role in causing clinical symptoms; however, research on systemic contact dermatitis to chromium and cobalt is limited.
Systemic Contact Dermatitis to Nickel (SCDN)
Nickel is the most common contact allergen. It is a metal found in zippers, jewelry, fixtures, stainless steel, cookware, eye glasses, braces, surgical implants, coins, keys, computers, phones, toys and more. Nickel is also the most common allergen reported to systemically induced contact dermatitis from a dietary perspective, this condition is known as systemic contact dermatitis to nickel (SCDN).
It is impossible to avoid nickel completely. Nickel is found naturally in food and water in varying amounts. Certain food contain higher amounts of nickel such as chocolate, nuts, seeds, beans, soy, whole grains, oats, and certain vegetables and fruits. The amount depends on the growing region and how food is prepared. Certain produce naturally contain nickel from the uptake of nickel in soil, whereas, heavily processed food or supplements can be contaminated with nickel through contact with machinery. Furthermore, certain food preparations or packaging methods are known to leach nickel into food, such as canning or cooking food in stainless steel.
Systemic Contact Dermatitis (SCD) to Cobalt
Cobalt is similar to nickel; it is a common metal used as an alloy. Nickel and cobalt allergy are frequently linked as they normally appear together in the environment. Cobalt is present in jewelry, metal fasteners, keys, surgical implants, electronics, polyester resin, paints, cement, clay, tattoos, hair dye and leather.
Cobalt is also found in our diet. Foods higher in cobalt include nuts, seeds, beans, chocolate, soy, organ meat, and some vegetables and fruits. Supplemental B12 also contains cobalt. As with nickel, the amount of cobalt in food depends on the growing region and how the food is prepared. Moreover, certain foods naturally contain cobalt and some are contaminated with cobalt through processing or packaging.
Systemic Nickel Allergy Syndrome
Some people who are sensitive to dietary sources of nickel also have gastrointestinal symptoms, this condition is known as systemic nickel allergy syndrome (SNAS). Symptoms that have been linked to systemic nickel allergy syndrome (SNAS) include:
Dermatitis in spite of strict avoidance of known allergens • Flares in patch test sites or previously healed rashes in the absence of direct exposures • Eye rashes • Headaches • Fatigue • Fibromyalgia • Heartburn • Abdominal pain • Nausea • Constipation • Diarrhea • Bloating • Rhinitis • Asthma • Chronic fatigue syndrome
Since systemic contact dermatitis (SCD) is a subset of allergic contact dermatitis (ACD), patch testing to diagnose ACD is a necessary first step in diagnosing SCD or SNAS. If dermatitis persists after strict avoidance of all allergens has been followed, then your provider may recommend trialing a low cobalt or low nickel diet. If symptoms have improved after a few weeks on a low nickel/low cobalt diet your provider may recommend an oral challenge to see if symptoms return. It takes on average 1-4 days after an exposure to experience symptoms. It can be helpful to document your symptoms and take pictures of your rashes to share with your doctor.
Unfortunately, not many providers acknowledge or are aware of systemically induced contact dermatitis (SCD) from dietary sources. It is helpful to familiarize yourself with the literature and share research articles with your doctors. Furthermore, investigating the presence of any surgical implants or dental work that may contain nickel or cobalt should be considered.
Strict avoidance of allergens is the most effective treatment. Individuals with systemic contact dermatitis (SCD) or systemic nickel allergy syndrome (SNAS) should see an improvement of dermatitis after trialing a low nickel/low cobalt diet for 6 weeks; however, it may take up to 4 months or longer on a restricted diet to clear rashes. A histamine intolerance may also contribute to worsening of eczema in people with SCD, trialing a low histamine diet may also help heal rashes. It is important to consult your doctor before trialing any restrictive diet.
Managing SNAS and SCD after symptoms resolve should include reintroducing foods higher in nickel and cobalt, on a rotation basis, to help fulfill nutrient needs and find where your personal threshold lies.
Other treatments your doctor may consider include corticosteroids, antihistamines, immunosuppressants, phototherapy, vitamin C, probiotics and iron supplementation. Certain countries offer oral hyposensitization to nickel.
Are you wondering if you have SCD and looking for guidance on how to manage your symptoms?