What is it?

Contact dermatitis can occur after weeks, months or even years of exposure to an item that was previously trouble-free.

It shows up as an itchy or swollen rash that can become flaky, blistered or scaly, if the reaction is more severe. Left untreated, the result is leathery, permanently discolored skin. If it strikes the hands and feet, it can become so disabling that people are unable to work, according to Mayo Clinic dermatologist Mark D.P. Davis, M.D.

Which is it: irritation or allergy?

When it comes to contact dermatitis, first consider the source.

• Irritant contact dermatitis: a burning or stinging rash after being in contact with a known skin-damaging irritant, such as detergent, dye or cleaning spray.
• Allergic contact dermatitis: swollen, dry or bumpy, red skin from contact with something most people consider harmless or an item that's never bothered you before.
• Photoallergy: a swelling or red rash that’s triggered only after exposure to UV light; specifically, if your skin is exposed to UV light after applying a product like sunscreen or perfume, you might develop a photoallergy. Occasionally, medication can cause this reaction, too, which is why some prescriptions come with a warning to avoid sunlight.

Nickel in bling and other things

You might’ve worn your favorite necklace for years, and then one day your neck’s decorated in pinkish patches. When your jewelry gives you a rash, the usual suspect is nickel. In fact, this light-colored metal has become the American Contact Dermatitis Society's Allergen of the Year for 2008.

The Dermatology Times reports that as body piercings have risen in popularity, nickel allergies are becoming more common, too. And nickel’s hard to avoid, as it’s mixed with other metals in everything from paper clips to drawer handles.

Bling on your clothes — such as snaps and buckles — frequently contains nickel, but it’s also found in places you might not expect, including: tomatoes, chocolate, canned goods, nuts and soy products.

Phoning it in

The latest buzz about nickel involves everyone’s must-have accessory: the cell phone. A study by the British Association of Dermatologists points to cell phones as the culprits in rising ear and cheek rashes in the U.K. Recent tests have also found that 10 out of 22 cell phone handsets in the U.S. contained traces of nickel.

Women are also more prone to nickel-related phone rashes. Because women typically wear more jewelry than men, they’re more likely to be sensitized (or already show signs of allergy) to nickel.

If you text more than you talk, you’re still vulnerable. Heavy cell phone typists could "in theory" get a finger rash from nickel-containing phones, says British dermatologist Graham Lowe, M.D.

Other potential foes

Nonmetal items are starting to catch up to nickel in the allergy department, dermatologist Joel DeKoven, M.D., tells the Dermatology Times. This includes plastic clogs and additives in plastic gloves — a potential concern for people who work in the food service, beauty and medical industries.

The Mayo Clinic also lists other frequent allergen offenders, including gold, thimerosal, topical antibiotics, scents found in household products and formaldehyde.

Vanquishing the rash

Don’t diagnose yourself or your treatment could make things worse. Consult your dermatologist to get the right mix of these rash-fighting tools:

• Over-the-counter ointments or antihistamines
• Prescription meds for stubborn cases or infections
• Barrier creams and coatings to give your skin some space from nickel
• Patch testing, which puts tiny allergen samples on your back for a few days

Finally, consider taking these lemons and make some lemonade: Tell would-be gift givers that inexpensive jewelry’s hazardous to your health, so you need the good stuff!

See also:

Itchy Skin (Pruritus)