Metal allergies are among the chief sources of allergic contact dermatitis. Nickel, cobalt and chromate are among the metals most likely to trigger reactions. Symptoms include a skin rash that can develop into blisters and damaged skin.
People are most often sensitized to metal from wearing costume jewelry, which frequently contains nickel. This problem has gotten worse as body piercing has grown more popular. Other sources of metal allergy include everything from soil and seawater to cement and shoe leather.
A metal allergy can be diagnosed by having a physician conduct a skin patch test, which introduces various allergens to a patient’s skin to see if a reaction occurs. Once an allergy has been diagnosed, patients should try to minimize exposure to the metal triggering their symptoms.
About metal allergies
After poison ivy, metal allergies are the second most common form of allergic contact dermatitis. They can cause redness, blistering and skin damage.
By far, the most likely source of a metal allergy is nickel, which is found in many metal products, including jewelry. Reactions are likely wherever jewelry contacts the skin, such as on the ears, nose, lips, tongue, navel, breasts and genitalia. Cobalt and chromate are also among the metals most likely to trigger reactions.
Traditionally, women have been more likely to be diagnosed with metal allergies because they have worn more jewelry. But this is changing as greater numbers of men wear jewelry. Also, men have higher incidences of metal allergy related to occupational exposures. Many construction materials contain metals that can trigger allergic reactions. Skin rashes associated with occupational metal exposure typically appear on the patient’s hands.
The increasing popularity of body piercing has led to an increase in the incidence of metal allergies in both men and women.
Potential causes of metal allergies
Metal allergies occur when people are exposed to certain metals and become sensitized to them. Once this process has taken place, a person will suffer an allergic reaction on the next exposure to the metal.
Metals that frequently are the source of metal allergies include:
- Nickel. The main culprit in metal allergies, it is found in many forms of jewelry. Nickel is also found in numerous other metal items, including zippers, buttons and snaps. Sweat allows metal ions to be absorbed more easily into the skin, making the problem worse in body regions prone to perspiration.
- Cobalt. Another common allergen, it is found in many of the same products as nickel. It is also found as a natural element in soil, dust and seawater. Cement, bricks, mortars and metal alloys also contain cobalt. So do blue pigments in porcelain, glass, pottery and ceramics, and in blue and green watercolor paints and crayons. It may be present in manufacturing processes for polyester resins. As a result, anything containing polyester may include cobalt.
- Chromate. The best–known form of chromate is a shiny finish applied to metal products (chrome). However, this form of chromate is unlikely to trigger symptoms. Another form of chromate, chromium salts, is the more common allergen. Chromium salts are present in cement, concrete and similar construction materials. They are used as a leather tanning agent and can cause “shoe dermatitis” in people who wear leather shoes that contain chromate. Some matches also contain chromate and touching unlit or previously lit matches can cause reactions on fingers or on any part of the body those fingers touch.
- Amalgam allergies. A rare reaction to the mercury used in the most popular form of dental filling. Patients who suffer amalgam allergies typically have a medical or family history of allergies to metals. In such cases, another restorative material must be used on the patient.
A huge array of everyday products may potentially trigger reactions in people with metal allergies. Below is just a sampling of products known to contain nickel, cobalt or chromate:
|Personal Items||Home & Office||Other|
|Cigarette lighters||Cutting tools||Carbide|
ear piercing needles
|Eyeglasses||Kitchen utensils||Coolant oils|
|Hair dyes||Metal chairs||Enamel|
|Handbag catches||Metal wool|
|Jeans studs||Newspaper||Magnetic tapes|
|Lipstick holders||Printer ink||Oils|
|Powder compacts||Thimbles||Rubber ties|
|Watchbands||TV screens||Vitamin B12|
|Zippers||Vacuum cleaners||Welding materials|
Nickel and other metals may be listed by other names, including:
|Cobalt (II) chloride-|
|Cobalt blue||Chromium salt|
Many implanted devices (e.g., surgical clamps, coronary stents) consist of, or contain, metals that can cause sensitivity or allergic reactions. As a result, patients should make all of their physicians aware of their metal allergies once they have been diagnosed.
Signs and symptoms of metal allergies
Symptoms of metal allergy usually appear within six to 24 hours after exposure to metal. Skin reaction usually is confined to the site that directly contacts the metal, but it can spread elsewhere. This often is the result of transferring the allergen from the fingertips to another part of the body, such as the face, eyelids or genitals. Symptoms typically associated with metal allergies include:
- Red, itchy, swollen skin
- Crusts and scales
- Skin darkening, or leathery and cracked skin
Symptoms associated with metal allergies usually will begin to fade once exposure to the metal has been discontinued.
Diagnosis methods for metal allergies
A physician attempting to diagnose a metal allergy will conduct a full physical examination of the patient. Compiling a medical history and a list of symptoms is also necessary.
Most physicians use a skin patch test to diagnose metal allergies. During this test, an absorbent pad will be soaked with suspected metal allergens and taped onto the skin of the patient for 24 to 72 hours. The amount of metal allergen on the pad should not cause any reaction in people not allergic to the metal. However, those who are allergic to the metal should react with a rash or wheal.
It can be very difficult in skin testing to distinguish between a nickel allergy and a cobalt allergy. Nickel and cobalt are found together in alloys and salts because it is too costly to separate the two metals. This is a problem in testing situations, as it is very difficult to obtain pure solutions of the individual metals. Therefore, patient history will be crucial to helping determine whether a patient is allergic to nickel, cobalt or both.
Treatment and prevention of metal allergies
Rashes that result from metal allergies often clear up by themselves once the skin is free of contact with the offending metal allergen. In some cases, a physician may prescribe a corticosteroid cream to clear up the rash and reduce itchiness.
Skin that is damaged by contact with metal must be carefully cared for until it heals. Moisturizers can keep the skin from peeling and cracking. Excessive scratching of skin with fingernails presents the risk of bacterial infection. If this occurs, antibiotics may need to be prescribed to cure the condition.
Desensitization techniques, such as allergy shots, are not effective for metal allergies. The only truly effective way to prevent metal allergies is to eliminate exposure to the allergen that triggers symptoms. This can be exceedingly difficult with metal allergies, because allergens such as nickel are present in so many products. However, brief contact with metals usually will not cause a reaction, even in allergic individuals. The key is to avoid regular, sustained skin contact with the allergen.
Steps that can be taken to reduce the likelihood of symptoms include:
- Wear nickel-free, plastic jewelry, stainless–steel, platinum, titanium or 18 karat gold.
- Try to use substitutes for metal, such as items made of wood, plastic, paper or fabric. Even if the object itself is metal, try to be sure that the portion that comes into contact with the skin – such as a handle – is not.
- Those prone to “shoe dermatitis” should change shoes and socks throughout the day, especially if their feet perspire excessively.
- Wear protective clothing to avoid skin contact with the allergen at home and in the workplace. However, do not use gloves for wet work unless they are 100 percent waterproof, as wet skin increases the penetration ability of metals. Also, some people may need to avoid latex gloves because latex is also a common allergen.
- Coat metal items such as keys or buckles with several layers of clear nail polish and cover them with tape. This provides a barrier to keep metals from direct contact with the skin.
- Check ingredients carefully in all products that may be potential sources of metal allergies. Do not purchase products that contain allergens likely to trigger a reaction.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to metal allergies:
- Do my symptoms suggest that I am allergic to metal?
- What tests will you use to determine if I am allergic to metal?
- What type of metal am I allergic to?
- Does my metal allergy pose a danger to my overall health?
- What treatment methods are available to me?
- What types of metal-containing objects should I avoid?
- Can I wear jewelry? If so, what kind?
- How long will my metal allergy-related rashes last?
- How can I prevent the area affected by the rash from becoming infected?
- Are my children more likely to develop metal allergies because I have the condition?