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Could It Be an Allergy?

Telling the difference between an allergic reaction and something else can be tricky.
By
WebMD Feature
Reviewed by Laura J. Martin, MD

Wondering if your nagging cold is actually an allergy? Or what about your new skin cream that made your hands break out? Distinguishing an allergy from a non-allergic condition is not always a clear-cut task. But knowing the difference can sometimes help you solve what's ailing you, which in turn could mean faster relief.

Mary Fields knows just how difficult pinpointing an allergy can be. The 64-year-old Bronx resident tells WebMD she was convinced her frequent hives were caused by something in her diet.

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"At first I thought I was allergic to chocolate, so I stopped eating that, but it still came back and even started to spread from my arms and legs to my back and thighs," says the retired nurse's assistant.

Fields' dermatologist referred her to allergist David Resnick, MD, FAAAAI, who ran a battery of allergy tests on her. "All the tests came back negative. This isn't an allergy. Her hives got increasingly worse with stress, which might be a part of it. But her symptoms are idiopathic, meaning their origin is unknown," says Resnick, who directs the allergy division of New York-Presbyterian Hospital/Columbia University Medical Center.

"I was a little surprised it wasn't food," says Fields, who says the hives started when her husband was diagnosed with a heart condition and needed to have a pacemaker implanted.  "I was going through a lot of stuff but I didn't realize I was worrying. So I'm trying to keep myself calm now, to start releasing some of the stress, and I guess I'll see if that stops the rash."

Mistaking Allergies: Easy to Do

Fields isn't alone in thinking an allergy was at the source of her outbreaks. Many people see just about any bad reaction to be an allergy, which isn't surprising, since more than half of all Americans test positive for at least one allergen, according to the American Academy of Allergy Asthma and Immunology.

Technically speaking, a true allergic reaction happens when the body mounts an unusual immune response to something that's normally harmless. Most allergy tests check for higher levels of antibodies known as Immunoglobulin E (IgE) in the blood, which are launched by the immune system to fight the invading substance.

As in Fields' case, food allergy is one of the more regularly misrecognized types of reactions among people trying to self-diagnose. "In general, it's more common to experience food intolerance than an actual allergy," says allergy specialist Alan Goldsobel, MD, FAAAAI. "For the majority of people who believe they have one, when they get tested it's not a true food allergic reaction," says Goldsobel, who is a clinical professor at the University of California, San Francisco, and adjunct associate professor at Stanford University Medical Center.

Goldsobel points out that although nearly 20% of adults claim they have a food allergy, studies show that only about 2% of adults have a true food allergy based on test results. And whereas almost 30% of parents say they think their child has a food allergy, the actual rates range from only 6% to 8% among children under age 6.

Regardless of whether it's food or other types of allergy, specialists say they rarely ever have to convince someone they have one. "It's always the other way around. I'm usually trying to persuade patients that they aren't allergic to something," Resnick tells WebMD.

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