Nickel Allergy Symptoms: Skin, Food (SNAS) and Diagnosis

This page summarizes published medical sources. It does not diagnose anything and does not replace a doctor. If you think you are allergic to nickel, talk to your doctor, a dermatologist or an allergist.

Nickel is the most common cause of contact allergy worldwide, according to a clinical review in Contact Dermatitis, and it affects women far more often than men (Ahlström et al., 2019). Nickel reaches the skin mostly from objects such as earrings, belt buckles, jeans buttons and watch straps. In some people who are already sensitized, nickel in food can also cause symptoms. These are two different situations with different symptoms and management.

Symptoms of contact nickel allergy

The most common form is allergic contact dermatitis. According to the Mayo Clinic, typical signs are:

• a rash or bumps where the metal touches the skin;
• itching, which can be severe;
• dry, thickened or cracked skin that can look like a burn;
• in stronger reactions, blisters that may leak fluid.

The classic spots are the earlobes (earrings), the wrists (watches, bracelets) and the belly around the navel (buckles and metal buttons). The reaction is delayed: it usually appears hours to a couple of days after contact and can last for weeks.

When to get emergency care: severe reactions are rare, but trouble breathing, swelling of the lips or throat, or suddenly feeling very unwell are an emergency.

Where the nickel comes from: objects and food

Objects

Nickel is in many metal alloys: costume jewelry, glasses frames, zippers, buckles, keys, coins and tools. In the European Union, the REACH regulation limits how much nickel can be released by items that stay in contact with the skin for a long time, such as jewelry and buttons (ECHA, REACH restrictions). Ahlström's review reports that this rule lowered how often people develop the allergy, but jewelry and metal accessories remain the main cause.

Food

Almost every food contains small amounts of nickel, plant foods especially. For most people this is not a problem. The European Food Safety Authority (EFSA, 2020) found, however, that in people who are already sensitized, a high intake of nickel from food can trigger eczema flare-ups. In the same opinion, grains and grain products are the largest source of nickel in the European diet, followed by beans, coffee, chocolate and breakfast cereals.

You cannot remove nickel from your diet completely. DermNet, the New Zealand dermatology reference site, says so directly, and adds that a low-nickel diet helps only a small number of patients.

SNAS: systemic nickel allergy syndrome

Some people with contact allergy have symptoms beyond the skin that touches metal. Italian allergists call this SNAS (systemic nickel allergy syndrome) and have studied it in detail (Ricciardi et al., 2014; Braga et al., 2013).

Reported symptoms include:

• skin: eczema, hives or itching in places that never touch metal;
• gut: bloating, stomach pain, diarrhea or constipation;
• general: headache and tiredness.

Many other conditions cause the same symptoms, from lactose intolerance to irritable bowel syndrome. SNAS is not something to self-diagnose from a symptom list.

How nickel allergy is diagnosed

1. Patch test. The standard test for contact allergy. A dermatologist or allergist tapes small amounts of nickel and other substances to your back and reads the reaction after about 48 to 72 hours.
2. Looking at the other symptoms. If the patch test is positive and you also have gut or widespread symptoms, the specialist may suspect SNAS.
3. Trial diet and challenge test. In the Italian studies, SNAS is suspected when symptoms improve after about a month on a low-nickel diet, and confirmed with an oral nickel challenge done under medical supervision.

A positive patch test on its own does not mean you need to change your diet. Many people with contact allergy eat normally with no problems.

How it is managed

Your specialist decides, case by case. The sources describe:

• Avoiding contact with items that contain nickel. This is the first step for everyone.
• Steroid creams or other prescribed treatment for the dermatitis.
• A low-nickel diet, only for people with symptoms linked to food, and only for a period your doctor sets. In a Danish trial, more than half of the selected patients improved on the diet (Veien et al., 1993), but results across studies are mixed.
• Oral hyposensitization, offered in some Italian centers for SNAS. This is a medical treatment and only done with an allergist.

Strict do-it-yourself diets cut many vegetables, legumes and whole grains. The risk is eating worse without a real benefit.

If your doctor gave you a diet

If your specialist gave you a list, that is the list to follow. To see where published lists place everyday foods, we made:

• a printable low-nickel food list (free PDF);
• a guide to foods high in nickel, including the foods the lists disagree on;
• what to eat with a nickel allergy, with a method to adapt the recipes you already cook;
• 7 easy low-nickel recipes made only with foods the lists rate low.

Sources

• Ahlström MG et al. Nickel allergy and allergic contact dermatitis: a clinical review. Contact Dermatitis, 2019. PubMed
• EFSA CONTAM Panel. Update of the risk assessment of nickel in food and drinking water. EFSA Journal, 2020. EFSA
• Ricciardi L et al. Systemic nickel allergy syndrome: epidemiological data from four Italian allergy units. Int J Immunopathol Pharmacol, 2014. PubMed
• Braga M et al. Systemic nickel allergy syndrome: nosologic framework and usefulness of diet regimen for diagnosis. Int J Immunopathol Pharmacol, 2013. PubMed
• Veien NK et al. Low nickel diet: an open, prospective trial. J Am Acad Dermatol, 1993. PubMed
• Mayo Clinic. Nickel allergy: symptoms and causes. mayoclinic.org
• DermNet. Nickel allergy. dermnetnz.org