Note: All links within content go to MayoClinic.com

Nickel is a metal found in many everyday items — from coins to belt buckles, and from jewelry to eyeglass frames.

Having an allergic reaction to nickel (nickel allergy) is common. In fact, nickel is one of the 10 most common causes of allergic contact dermatitis — a skin inflammation resulting in swollen, reddened and itchy skin due to direct contact with an allergen.

A nickel allergy may develop after your initial exposure to items containing nickel, or after repeated or prolonged exposure to nickel. In most cases, the resulting rash occurs only at the site of contact, though it may be found on other parts of your body as well.

Nickel allergy affects people of all ages. In most cases, it's a minor annoyance. However, in severe cases, the rash and extreme itching can be disabling — especially when located on your hands. There's no cure for nickel allergy. The best approach to nickel allergy is to avoid contact with nickel.

If you have a nickel allergy, exposure with items containing nickel may cause a tingly, itching feeling as soon as 20 minutes after contact with your skin.

Within one or two days of contact, other signs may include:

• A red, swollen rash
• Watery blisters

The cause of a person's sensitivity to nickel is often unknown, although in some people it may start with nickel in the first pair of earrings or even the nickel-containing needle used to pierce ears or another body part.

Your skin normally doesn't react the first time it's exposed to an allergen. Instead, it can take many exposures for your skin to become sensitive to nickel. Once a nickel allergy has been established, your skin will always be sensitive to nickel. Your skin may then become inflamed, itchy or dotted with bumps or blisters within hours or days after contact with nickel. Sweating while wearing an item containing nickel can increase your chance of dermatitis.

You may come in contact with nickel through common items such as:

• Jewelry, including earrings, rings, bracelets and necklaces
• Watchbands
• Belt buckles
• Clothing fasteners, such as zippers, snaps and bra hooks
• Suspender clips
• Hairpins
• Eyeglass frames
• Coins
• Pens
• Utensils
• Paper clips
• Keys
• Tools

Some believe that drinking water and foods that are high in nickel — such as chocolate, salmon, legumes, nuts, grains, potatoes, and canned fruits and vegetables — may cause nickel allergy in a small percentage of people. But this is highly controversial, and more research is needed.

Nickel allergy is more common in women. This may be because women are more likely to have their ears pierced, which may expose their bodies to nickel for several days before the holes heal, and to have more frequent exposure to earrings and other jewelry.

With the increasing popularity of body piercings, nickel allergy is becoming more common in men as well.

People who have regular exposure to nickel on the tops of their hands, feet or abdomen while doing "wet work" (either as a result of sweat or frequent contact with water) may be more likely to develop nickel allergy. This may include, for example, bartenders or people who work in certain food industries.

If you have the signs and symptoms of a nickel allergy, such as a red, swollen rash at the site of a piece of jewelry or a belt buckle, first try to avoid the source of nickel. If avoidance does not bring relief, see your doctor.

If you have a nickel allergy and are currently having a reaction to nickel, contact your doctor if your skin isn't healing properly or your symptoms appear to be getting worse.

Your doctor may be able to diagnose a nickel allergy based on your skin's appearance and your recent history of contact with nickel.

If the cause of your rash isn't apparent, however, your doctor may recommend a patch test (contact hypersensitivity allergy test).

During a patch test, small quantities of potential allergens (including nickel) are applied to small patches, which are then placed on your skin to check for a reaction. The patches remain on your skin for two days before being evaluated by your doctor. 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.

There's no cure for nickel allergy. Instead, identifying sources of nickel and avoiding nickel is the primary form of treatment.

There are, however, temporary solutions for the rashes and blisters that mark a nickel allergy. These may include:

• Corticosteroids. High-potency topical corticosteroid creams, such as clobetasol propionate (Temovate, others), can help speed the disappearance of and improve the appearance of the rash and blisters. In severe or widespread cases, your doctor may prescribe oral corticosteroids.
• Wet compresses. Compresses containing Burow's solution, an over-the-counter medication containing aluminum acetate, may help dry blisters and relieve itching. Diluted white vinegar (1 ounce of vinegar to 16 ounces of water) also may be effective.
• Moisturizing creams. These can help soften dry, rough skin and alleviate itching.
• Antihistamines. These medications, such as diphenhydramine (Benadryl) or loratadine (Claritin), can help alleviate itching.

Even with the above measures, it may take weeks to months for the rashes and blisters associated with nickel allergy to clear up completely.

You may be able to reduce your risk of developing a nickel allergy by taking precautions when having your ears or another part of your body pierced. The incidence of nickel allergy has been on the rise with the increase in body piercings.

Have piercings performed by a reputable establishment that uses only sterile, stainless steel needles. Also, wear only nickel-free (stainless steel or solid gold) jewelry for at least the first three weeks.

If you already have a nickel allergy, you can help prevent outbreaks by avoiding direct, prolonged contact with nickel or nickel-plated products. Follow these tips:

• Watch what you buy. Buy only hypoallergenic, stainless steel, solid gold, sterling silver or plastic jewelry.
• Create a buffer. If you're unsure if a piece of jewelry, such as a ring or earrings, contains nickel, apply clear nail polish to it to create a layer between the metal and your skin. You may also purchase plastic covers specifically for protecting your ears from nickel-containing earrings.
• Watch for 'hidden' offenders. Consider watchbands, zippers, eyeglass frames, belt buckles, coins and anything you come in contact with that's made with metal.
• Use items made of other materials. Use clothing fasteners — such as snaps, clasps and zippers — made only of plastic or coated or painted metal.

If you're very sensitive to nickel, your doctor may recommend avoiding foods that are high in nickel — such as chocolate, salmon, legumes, nuts, grains, potatoes, and canned fruits and vegetables. However, whether nickel in foods can cause a nickel allergy is highly controversial.

While there's evidence that eating foods containing nickel may cause the rashes and blisters associated with nickel allergy, this occurs in a very small percentage of people. Also, it's impossible to avoid consuming nickel completely because it's found in so many foods — including tap water.