Why 3 out of 4 people who think they have a food allergy are really wrong

You might be avoiding peanut butter or shrimp for no reason: Most people who think they have a food allergy actually don’t, new research in Annals of Allergy, Asthma, & Immunology suggests.

Out of more than 2,000 people in the study who reported having a food allergy, only 28 percent of them actually tested positive for the allergen they believed they had.

One reason? Many people who think they have a food allergy to a specific food only have an intolerance to it, says lead researcher Melanie Makhija, M.D., of the Ann & Robert H. Lurie Children’s Hospital of Chicago.

A food intolerance doesn’t trigger a histamine response in the same way a food allergy would. That means the immune system isn’t affected. And more importantly, it doesn’t cause a life-threatening situation like anaphylaxis that some severe food allergies do.

But because the symptoms of food intolerance are so similar—like nausea, digestive discomfort, bloating, migraines or hives—it can be easy to mistake it with an allergy, Dr. Makhija says.

It’s also possible that you could have once had an allergy to a certain food, but later outgrow it, she says. For example, about 80 percent of kids who have a milk or egg allergy outgrow it by their adult years, according to Dr. Makhija.

It’s not exactly clear why this happens, but the prevailing theory is that the immune system matures enough to handle the formerly offending foods. But if they don’t try those foods again—or get re-tested for allergens—they could believe they are still allergic.

So what’s your move if you’ve tested allergic to foods like nuts, strawberries, or milk as a kid—or experienced allergic-type reactions after eating them? These findings definitely don’t give you free rein to chow down on the food you think you’re allergic to.

Because if you haven’t outgrown the allergy, you can still experience severe reactions like digestive upset or even respiratory distress. And even if you don’t have an actual allergy and are just intolerant to the food, eating it can make you feel pretty miserable.

So get the pros to check you out. If you’ve never been tested—or if the last time you’ve been tested was as a child—ask your doctor about getting it rechecked. Your doctor may refer you to an allergist, who specializes in asthma, allergy and immunology.

He or she will perform allergen testing. Blood tests, which measure your antibody response to specific foods, are generally more accurate than skin tests, which involve scratching or pricking the skin with minute amounts of potential allergens, says Dr. Makhija.

But it’s not just as easy a reading a test result: Your doctor will also take into account family history and past reactions to eating certain foods. This additional information can help determine if it’s a true allergy, says Dr. Makhija. If it’s not, your allergist can advise you on how to go about trying the food again.