What is the difference between a food allergy, sensitivity and intolerance? Experts break it down

Health issues related to food have become a hot topic over the past few years, with people often wondering if they may have a food allergy, intolerance or sensitivity after having a reaction. While many people are aware that not everyone reacts the same way to certain foods, the lingo is a little confusing.

Some people may claim they have an allergy to certain foods when what they actually mean is that they have an intolerance or sensitivity. True food allergies affect an estimated 8% of children in the U.S., according to the Centers for Disease Control and Prevention; in adults that number is closer to 4%, per the American College of Allergy, Asthma & Immunology (ACAAI). It can be trickier to determine how many people have a food sensitivity or intolerance.

So what exactly is the difference between these things, and how can you know if you're experiencing one of them? Experts break it down.

What is the difference between a food allergy, sensitivity and intolerance?

A food allergy occurs when the body has a specific immune response to certain foods that is "reproducible," meaning that it will happen again, according to the CDC. "Someone with a true food allergy would react every time they eat the food, regardless of how it is prepared," Dr. Scott Feldman, assistant professor of medicine and allergy and immunology clinic director at the University of Pennsylvania Perelman School of Medicine, tells Yahoo Life.

In the case of food allergies, the body's immune system mistakenly sees certain foods or ingredients as harmful.

According to the CDC, these are the foods or food groups responsible for most serious food allergies in the U.S.:

• milk

• eggs

• fish

• crustacean shellfish

• wheat

• soy

• peanuts

• tree nuts

Food sensitivity and intolerance are a little less well defined, Dr. Kara Wada, allergist and immunologist at the Ohio State University Wexner Medical Center, tells Yahoo Life. "The terms are often used interchangeably," she says.

"Intolerance is best thought of as an inability to digest a particular food," Feldman says. It's often linked to your gut microbiome, the good bacteria that live in your gut, he says. Not being able to digest a particular food can cause uncomfortable symptoms, but it won't lead to extreme ones like those you can experience with an allergic reaction, Wada explains. (More on those in a minute.) People with a food intolerance can usually eat small amounts of a certain type of food without having issues, according to the American Academy of Allergy, Asthma & Immunology.

The term "food sensitivity" is used "pretty commonly" to refer to "particular foods that aren't triggering an allergy, but maybe are felt to trigger some other symptoms," Wada says.

"Food sensitivities and intolerances primarily cause gastrointestinal symptoms only," she continues. Common culprits are high FODMAP foods — short-chain carbohydrates that your small intestine doesn't do a good job of absorbing. These include dairy-based milk, yogurt and ice cream, wheat-based products, asparagus, onions, garlic, apples, cherries and peaches, according to Johns Hopkins Medicine. "Some people experience digestive distress after eating them," Wada says.

Feldman notes that food sensitivity and intolerance are "more common, especially in adults," than food allergies. "It is rare to develop a new food allergy as an adult in a food that was prior tolerated," he says.

Signs of a food allergy vs. intolerance or sensitivity

The symptoms of a food allergy can include, per the ACAAI:

• vomiting and/or stomach cramps

• hives

• shortness of breath

• wheezing

• repetitive cough

• shock or circulatory collapse

• tight, hoarse throat or trouble swallowing

• swelling of the tongue, affecting the ability to talk or breathe

• weak pulse

• pale or blue coloring of skin

• dizziness or feeling faint

• anaphylaxis, a potentially life-threatening reaction that can send the body into shock

Many symptoms of an allergy happen "within minutes," Wada says, although the ACAAI notes it can take up to two hours for symptoms to start. "Your body will respond in a pretty telltale way," she says.

Symptoms of a food intolerance or sensitivity can be a little different. They tend to mostly be GI-related, Wada says, and can include symptoms such as:

• cramping

• diarrhea

• constipation

• bloating

• gas

How to prevent a reaction

There is no cure for food allergies, and avoiding the allergen is the only way to prevent a reaction, according to the CDC.

"Due to the allergic antibodies, ingestion of very small amounts of a food can lead to a severe, serious, life-threatening allergic reaction," Feldman says. "This is why strict avoidance of the food is needed, and food labels are important."

That includes avoiding cross-contamination, Wada says — making sure that someone with an allergy doesn't touch or use a shared cutting board, knife or other tools used to prepare foods containing their allergen.

You can also prevent a reaction by avoiding foods that you have a food sensitivity or intolerance to, Wada notes.

How to treat a food allergy, sensitivity and intolerance

In the case of a food allergy, avoidance is the most important step, Wada says. However, people with a food allergy may be prescribed an epinephrine auto injector (like an EpiPen) to carry in case of accidental exposure and symptoms, Feldman says.

With a food intolerance or sensitivity, Wada says, it may be possible for some people to build up a tolerance. "I like to try to help my patients work toward that ability to digest certain foods," she says. "Sometimes it's preparing foods in certain ways or starting with small amounts of the food and building up. It's like doing a workout for your body."

If you suspect you have a food allergy, experts say it's a good idea to talk to an allergist. "If you had a reaction that could have been triggered by a food, an allergist can help listen to the details, ask questions and perform testing to look for specific food triggers," Feldman says. "Some reactions or symptoms end up being from other causes that are not specific foods."

But if you're having symptoms of an intolerance or sensitivity, Wada suggests starting with your primary care doctor or a gastroenterologist. "Keep a journal of symptoms, along with when it's happening, for how long and how it's interfering with your quality of life," she says. Your doctor should be able to help from there.

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