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Food Allergies vs. Intolerance: What’s the Difference?


Between 1997 and 2008, the prevalence of peanut or tree nut allergy appears to have more than tripled in U.S. children.

Peanuts, tree nuts, fish, and shellfish commonly cause the most severe reactions.

“I can’t eat that, I’m allergic,” your friend says to you at a restaurant over the weekend. While that may be true, many people use the term “food allergy” when they may really mean they have a food intolerance. It’s understandable since many symptoms of a food allergy and food intolerance overlap, but they’re actually very different. A food allergy can be severe and life-threatening – if you have one, you must avoid even small amounts of the food that causes the allergy.

It’s estimated that as many as four percent of adults in the United States – or over 12 million Americans – have a food allergy. Many more have a food intolerance. Knowing the difference is important for allergy suffers as well as their family and friends.

Food Allergies and Your Immune System

The key difference between a food allergy and food intolerance is how your immune system is involved. A food allergy will cause your immune system to react; food intolerance will not.

Your immune system exists to protect your body from harmful substances, such as germs, that would make you sick. If you have a food allergy, your body mistakes harmless food for something bad – and your immune system goes into action to attack it. If you have a true allergy, this type of reaction will happen every time you eat the food you’re allergic to.

An allergic reaction may happen even if you have a very small amount of the food in question. For instance, someone with a severe peanut allergy may react if they eat another food prepared in the same factory with peanuts, since even peanut dust can trigger an allergy.

The Symptoms of Food Allergies and Food Intolerance

Food allergies and food intolerance have some of the same symptoms, which is why many people confuse them. They both may cause stomach issues such as nausea, pain, diarrhea, and vomiting.

A food allergy, however, will also create systemic reactions – which means the whole body may be affected. The symptoms unique to a food allergy are:

  • Skin issues, such as a rash or hives
  • Trouble breathing
  • Chest pain
  • A sudden drop in blood pressure

These symptoms can come on fast and be severe – and they’re most certainly an emergency that requires immediate attention. The person with the allergy may need to use an epinephrine auto-injector (EpiPen) if they have a prescription, and then call 911.

A food intolerance, on the other hand, will come on gradually. It may only happen if you eat a lot of the food in question, or if you eat it frequently. It’s uncomfortable but not a medical emergency. A gastroenterologist may be able to help you manage symptoms of a food intolerance.

Get an Accurate Diagnosis

Food allergies can be dangerous, so it’s not a good idea to self-diagnosis if you think you may have one. It’s better to talk to your doctor and see an allergist to make sure.

The allergist will use a combination of your medical history, a skin-prick test, and a blood test to measure the response of your immune system when exposed to the food that may be causing the allergy. You may also be given an oral food challenge, which involves ingesting some of the food in question. It’s important that a doctor performs this test to make sure you receive the proper medical care if you have an allergic reaction.

Managing food allergies and food intolerance is important to living a healthy and comfortable life – talk to your doctor today if you’re having a bad reaction to the foods you eat.

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