This Is the Difference Between Food Intolerance & Food Allergies

Oct 7, 2018 at 10:00 a.m. ET
Shelled peanuts in a bowl on a red and white checkered tablecloth
Image: Tim Grist Photography/Getty Images.

These days, it seems like just about everyone is following a special diet. From gluten and lactose intolerances to peanut and shellfish allergies, it appears no food is safe when it comes to our health. 

If you’re experiencing symptoms of indigestion and nausea post-meal, you might wonder whether you fall into one of those categories yourself. But you might also be wondering what the difference is between a food intolerance and a food allergy. 

Food intolerances vs. food allergies

“People often come to my office with concerns for food allergy and intolerance not knowing that there is a difference,” Dr. Kathleen Dass, an allergy immunologist at Michigan Allergy, Asthma & Immunology Center, tells SheKnows. “A food allergy is mediated by the immune system and can occur with even tiny amounts of food. Patients with true food allergy cannot eat the food they are allergic to. On the other hand, food intolerance is not mediated by the immune system. Symptoms are usually predictable and the same with each ingestion.”

Common food intolerances include lactose intolerance, celiac disease, fructose intolerance, alcohol dehydrogenase deficiency, sulfite sensitivity and sometimes dye sensitivity, Dass explains. Common food allergies include peanuts, tree nuts, milk, egg, soy, wheat, fish and shellfish.

While the symptoms of a food intolerance and food allergy can be similar, the key difference between the two comes down to life or death. An intolerance might make your belly ache, but an allergy can kill you. Both can cause vomiting, diarrhea and bloating, but an allergy can also affect the skin in some way. 

“Food intolerances usually can cause bloating, diarrhea, nausea or upset stomach. Some people also complain of headaches or fatigue,” Dr. Purvi Parikh, allergist/immunologist with Allergy & Asthma Network, tells SheKnows. “A food allergy almost always has some type of skin involvement — like rash, itching, swelling — and can be accompanied by coughing, wheezing, trouble breathing, nausea, vomiting or diarrhea, dizziness or loss of consciousness.”

Diagnosis & treatment

Knowing the difference is key when it comes to diagnosis and treatment. To determine if you have a food intolerance vs. food allergy, Dass recommends having an evaluation by an allergist/immunologist. 

“A thorough history should be taken to find out the symptoms fit a description for allergy or intolerance," she says. "After that, your allergist may recommend skin testing. Sometimes, the skin testing for food can be falsely positive. This is where having the history is helpful.” 

After skin testing, your allergist may want to do blood tests because sometimes, there may be still be a question of food allergy vs. food intolerance. Your allergist may recommend an oral food challenge, where you eat incrementally larger amounts of the food in question under medical supervision followed by close monitoring, Dass says.

Once diagnosed, Parikh says food intolerances aren't dangerous like food allergies, so you may not need to avoid the food completely. She says that sometimes, eating less of a food or trying it in a different form can help; for example, people who are lactose-intolerant may be able to eat yogurt or cheese but not milk. "A simple rule of thumb is: If you feel better without it, avoid it," she adds.

More: This Keychain Could Save the Lives of People With Food Allergies

However, if you are diagnosed with a food allergy, both Parikh and Dass say you most certainly should avoid that particular food. While it is possible to outgrow some food allergies, Parikh says there is no guarantee. “It is dangerous to keep eating [something] you are allergic to, as reactions can get worse on subsequent exposures,” she explains.

Dass also recommends having an emergency plan of action if you have a food allergy, including knowing how to use an auto-injectable epinephrine device (e.g., an EpiPen). “Make sure to notify any waitstaff at restaurants of your food allergy and carefully read labels,” she adds. 

More: What You Can Do to Prepare for Allergy Season Now

What the diagnosis means for you

While a diagnosis of food intolerance or allergy may be disappointing, Dass says there is still hope left for those who dream of eating peanut butter sandwiches again. “Because food allergy is increasing in prevalence, more research and advancements are being made,” she says. “We are also learning more about specific components in the food that lead to the food allergy.” 

She cites a landmark study called the LEAP study that helped to identify children who are at highest risk for peanut allergy to potentially prevent the allergy from occurring. 

"Also, Xolair, a subcutaneous injection, is currently being fast-tracked by the FDA for prevention and treatment of food allergy. While not FDA-approved yet, some allergists are performing oral immunotherapy to desensitize patients to specific foods," she adds. 

Maybe someday, peanut butter sandwiches on gluten-y bread can be a reality for those who’ve been doing without. But for now, if you're diagnosed with a food allergy, it's best to avoid it.

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