Nickel allergy is one of the most common causes of allergic contact dermatitis — an itchy rash that appears when your skin touches a usually harmless substance.

Nickel allergy is commonly associated with earrings and other jewelry, particularly jewelry associated with body piercings. But nickel can be found in many everyday items — from coins to zippers, from cellphones to eyeglass frames.

Nickel allergy can affect people of all ages. A nickel allergy usually develops after repeated or prolonged exposure to items containing nickel. Treatments can reduce the symptoms of nickel allergy. Once you develop nickel allergy, however, you will always be sensitive to the metal and need to avoid contact.

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If you have nickel allergy and you're exposed to a nickel-containing item, the allergic reaction (contact dermatitis) usually begins within 12 to 48 hours after exposure. The reaction may persist for as long as two to four weeks. The features of contact dermatitis usually appear only where your skin came into contact with nickel, but they may appear elsewhere on your body. Nickel allergy signs and symptoms include:

• Rash or bumps on the skin
• Itching, which may be severe
• Redness or changes in skin color
• Dry patches of skin that may resemble a burn
• Blisters and draining fluid in severe cases

When to see a doctor

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An allergic reaction is somewhat like a case of mistaken identity within your body's immune system. Normally, your immune system reacts to protect your body against bacteria, viruses or toxic substances.

If you have nickel allergy, your body reacts to nickel and possibly to other metals, such as cobalt and palladium. In other words, it's mistakenly identified nickel as something that could harm you. Once your body has developed a reaction to a particular agent (allergen) — in this case, nickel — your immune system will always be sensitive to it. That means anytime you come into contact with nickel, your immune system will respond and produce an allergic response.

Your immune system's sensitivity to nickel may develop after your first exposure or after repeated or prolonged exposure. The cause of nickel allergy is unknown, but sensitivity to nickel may, in part, be inherited (genetic).

Sources of nickel exposure

Nickel allergy is most commonly associated with earrings and other jewelry for body piercings that contain some nickel. Common sources of nickel exposure include:

• Jewelry for body piercings
• Other jewelry, including rings, bracelets, necklaces and jewelry clasps
• Watchbands
• Clothing fasteners, such as zippers, snaps and bra hooks
• Belt buckles
• Eyeglass frames
• Coins
• Metal tools
• Cellphones
• Keys

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Your doctor can usually diagnose nickel allergy based on your:

• Skin's appearance
• Recent history of contact with items that may contain nickel

If the cause of your rash isn't apparent, however, your doctor may recommend a patch test (contact hypersensitivity allergy test). He or she may refer you to an allergy specialist (allergist) or a skin specialist (dermatologist) for this test.

Patch testing

During a patch test, very small quantities of potential allergens (including nickel) are applied to your skin and covered with small patches. The patches remain on your skin for two days before the doctor removes them. If you have a nickel allergy, the skin under the nickel patch will be inflamed when the patch is removed or in the days after removal of the patch.

Because of the low concentrations of allergens used, patch tests are safe even for people with severe allergies.

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The best strategy to prevent developing nickel allergy is to avoid prolonged exposure to items containing nickel, especially jewelry. If you already have a nickel allergy, the best way to prevent an allergic reaction is to avoid contact with the metal.

However, it's not always easy to avoid nickel because it's present in so many products. Home test kits are available to check for nickel in metal items. The following tips may help you avoid nickel exposure:

Wear hypoallergenic jewelry

Purchase jewelry that's made of materials that aren't likely to cause allergic reactions. Look for jewelry made from such metals as nickel-free stainless steel, surgical-grade stainless steel, titanium, 18-karat yellow gold, or nickel-free 14-karat yellow gold, sterling silver, copper and platinum. Avoid jewelry with nickel, as well as cobalt and white gold, which may contain nickel and trigger allergic reactions. Surgical-grade stainless steel may contain some nickel, but it's generally considered hypoallergenic for most people.

Get rid of jewelry that contains nickel or has caused an allergic reaction. Be sure that your earring backings also are made of hypoallergenic materials.

Choose a piercing studio carefully

Tattoo and body piercing studio regulations differ from state to state. Contact your state or local health department to find out what rules apply to your area and be certain to choose a reputable studio with licensed piercers.

Visit a studio before getting a piercing to make sure that the piercer:

• Provides a clean, tidy, professional environment
• Uses sterile, nickel-free or surgical-grade stainless steel needles in sealed packages
• Sells only hypoallergenic jewelry and can provide documentation of metal content
• Doesn't use a piercing gun, which may not be sterile or nickel-free and may cause other complications, such as a bacterial infection

Use substitute materials

Look for safer substitutes for common nickel-containing items:

• Watchbands made of leather, cloth or plastic
• Zippers or clothing fasteners made of plastic or coated metals
• Plastic or titanium eyeglass frames

Create a barrier

If you have to be exposed to nickel at work, creating a barrier between you and the nickel may help. If your hands have to touch nickel, wearing gloves may help. Try covering buttons, snaps, zippers or tool handles with duct tape. Clear nail polish on jewelry may help, but may have to be reapplied often.

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You may use some of the following treatments at home to treat contact dermatitis due to nickel allergy. If these treatments don't help or the rash worsens, contact your doctor. Home remedies include the following:

• Use soothing lotions, such as calamine lotion, which may ease itching.
• Moisturize regularly. Your skin has a natural barrier that's disrupted when it reacts to nickel and other allergens. Using emollient creams or lotions, such as petroleum jelly or mineral oil, could reduce your need for topical corticosteroids.
• Apply wet compresses, which can help dry blisters and relieve itching. Soak a clean cloth in Burow's solution, an over-the-counter medication containing aluminum acetate; diluted white vinegar (1 ounce of white vinegar to 16 ounces of water); or tap water. Place the compress over the rash for 15 to 45 minutes. You can repeat this process several times a day.
• Apply over-the-counter topical corticosteroids (hydrocortisone), which may lessen itching and improve the rash. You can apply to the affected area before applying a wet compress to allow better penetration into the skin. Talk to your doctor about how long you can safely use the product.
• Try over-the-counter oral antihistamines, such as diphenhydramine (Benadryl), which may help relieve itching for a short time, but tend not to be effective for this type of allergy.

Avoid certain over-the-counter ointments, such as antibiotic creams, which may contain ingredients — particularly neomycin — that can worsen an allergic reaction.

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Certain factors may increase your risk of developing a nickel allergy, including:

• Having ear or body piercings. Because nickel is common in jewelry, nickel allergy is most often associated with earrings and other body-piercing jewelry containing nickel. If the first jewelry you wear after a piercing contains nickel, your body is constantly exposed to the metal during the healing time. And people who have piercings often wear jewelry every day. The more piercings you have, the greater your risk of developing a nickel allergy.
• Working with metal. If you work in an occupation that constantly exposes you to nickel, your risk of developing an allergy may be higher than it is for someone who doesn't work with the metal. In addition, people who have regular exposure to nickel while doing "wet work" — as a result of either sweat or frequent contact with water — may be more likely to develop nickel allergy. These people may include bartenders, people who work in certain food industries and domestic cleaners. Other people who may have an increased risk of nickel allergy include metalworkers, retail clerks and hairdressers.
• Being female. Women and girls are more likely to have a nickel allergy than are men and boys. This may be because females tend to have more piercings and get them at a younger age.
• Having a family history of nickel allergy. You may have inherited a tendency to develop a nickel allergy if other people in your family are sensitive to nickel.
• Being allergic to other metals. People who have a sensitivity to palladium, cobalt or chromium may also be allergic to nickel.

Source: http://www.mayoclinic.com