Millions of Americans incorrectly think they have food allergies, study finds

New research suggests Americans may be over-diagnosing themselves with food allergies. A study published in the medical journal JAMA Network Open estimates that nearly 19 percent of adults think they have food allergies, but less than 11 percent actually do.

Experts say the discrepancy likely comes from misuse of terminology.

"Most people when they say they have an allergy, it's likely an intolerance," Dr. Tania Elliott, an allergist with NYU Langone Health, told "CBS This Morning." "They have a headache. They don't feel well. They get bloated. They have stomach discomfort."

In reality, an allergic reaction can be life-threatening.

"Ninety-percent of the time you're going to have skin symptoms," Elliott said. "Hives, swelling, itching, redness all caused by a chemical called histamine which is what's released from allergy cells when an allergic reaction occurs."

Milder allergies may not show noticeable symptoms for several hours. However, more dangerous allergies can lead to anaphylaxis, a severe and sudden reaction that can occur within minutes of exposure. If not treated quickly, anaphylaxis can lead to death.

For the study, researchers from Northwestern University surveyed more than 40,000 adults from across the United States. Participants were asked if they had food allergies and for a description of their symptoms. They were also asked if they'd ever received a formal test and diagnosis of a food allergy by a doctor.

"While we found that one in 10 adults have food allergy, nearly twice as many adults think that they are allergic to foods, while their symptoms may suggest food intolerance or other food related conditions," lead author Ruchi Gupta, MD, MPH, a professor of pediatrics at Northwestern University Feinberg School of Medicine, said in a statement. "It is important to see a physician for appropriate testing and diagnosis before completely eliminating foods from the diet."

The study also found that only half of adults with a "convincing" food allergy had a physician-confirmed diagnosis, and less than 25 percent reported a current epinephrine prescription, like an EpiPen, for treatment of a severe allergic reaction.

"If food allergy is confirmed, understanding the management is also critical, including recognizing symptoms of anaphylaxis and how and when to use epinephrine," Gupta said.

The researchers say their data indicate that the most prevalent food allergens among U.S. adults are:

• Shellfish (affecting 7.2 million adults)
• Milk (4.7 million)
• Peanut (4.5 million)
• Tree nut (3 million)
• Fin fish (2.2 million)

Elliott said if you think you have a food allergy, it's important to take the right steps to get a proper diagnosis.

"Make sure you see an allergy specialist," she said. "These folks have numbers of years of training to make sure they can hone in on the exact allergy that you have and then educate you on accidental ingestions."