A Parent’s Guide to Non-IgE-Mediated Food Allergies

What are non-IgE-mediated food allergies? How are they different from more “traditional” food allergies? We’ll answer these questions and more in this parent’s guide.

What are non-IgE-mediated food allergies, and how are they different from more “traditional” food allergies? What are common symptoms and types of these allergies? How are these allergies diagnosed and managed? We’ll answer these questions and more in this parent’s guide to “delayed-type” food allergies.

What Are Non-IgE-Mediated Food Allergies?

Food allergies can be divided into two main categories: IgE-mediated and non-IgE-mediated food allergies. Both categories of allergies involve the immune system, but each presents in different ways. To understand what non-IgE-mediated food allergies are, it’s important to know how they differ from IgE-mediated food allergies.

Here are some of the main differences between the two categories of food:
Category of Food Allergy IgE-Mediated Non-IgE-Mediated
Is the immune system involved? Yes Yes
Are IgE antibodies involved? Yes No
Common symptoms in babies Hives, swelling, vomiting GI symptoms (diarrhea, vomiting, stomach pain, abdominal pain)
When do symptoms usually appear? Seconds to minutes after consuming food; almost always within 2 hours Hours to days after consuming food; sometimes takes 2-3 days
Can skin prick tests help diagnose the food allergy? Yes No
Can blood tests help diagnose the food allergy? Yes No
Can the allergy cause severe allergic reactions? Yes Very rarely

IgE-mediated food allergies

  • IgE-mediated food allergies are the allergies responsible for the more “traditional” allergic reactions that people usually associate with food allergies.
  • When someone has an IgE-mediated food allergy, their body produces special IgE antibodies that over-defend the body against a specific food. These IgE antibodies cause their immune system to trigger an allergic reaction when they eat that food.
    • For example, if someone has an IgE-mediated peanut allergy, their immune system produces peanut-specific IgE antibodies that over-defend the body against peanut, and that trigger a reaction whenever they eat peanut.
  • Common symptoms of IgE-mediated food allergies include hives and swelling.
  • Symptoms of an IgE-mediated food allergy usually show up seconds to minutes after baby consumes the food they’re allergic to, and almost always occur within two hours.
  • Since their symptoms appear quickly and are more typically associated with food allergies, IgE-mediated food allergies are usually easier to diagnose than non-IgE-mediated food allergies.
    • Skin prick and blood testing also makes IgE-mediated food allergies easier to identify, since these tests check for specific IgE antibodies.

Non-IgE-mediated food allergies

  • Non-IgE mediated food allergies also involve the immune system, but they don’t involve IgE antibodies.
  • These allergies are different from the more “traditional” food allergies, as they don’t cause hives or swelling.
  • The exact causes of non-IgE-mediated food allergies are not widely understood, but all of these allergies cause symptoms that involve different parts of the gut.
  • Common symptoms of non-IgE-mediated food allergies include gastrointestinal symptoms, such as stomach pain, abdominal pain, diarrhea and vomiting. (You can find a more complete list of symptoms below).
  • Symptoms of a non-IgE-mediated food allergy usually occur hours to days after someone consumes the food they’re allergic to. Sometimes, it will take 24-72 hours (2-3 days) before symptoms appear.
    • This is why non-IgE-mediated food allergies are often called “delayed food allergies.”
      • There are no blood or skin prick tests that can accurately diagnose non-IgE-mediated food allergies.
      • This, combined with the delayed symptoms, makes non-IgE-mediated food allergies harder to diagnose.

      Symptoms of Non-IgE-Mediated Food Allergies in Babies

      Symptoms of non-IgE-mediated food allergies vary depending on the specific type of food allergy your baby has. However, all types of non-IgE mediated food allergies cause gastrointestinal (GI) symptoms.

      Common symptoms of non-IgE-mediated food allergies in babies include:

      • Diarrhea
      • Vomiting
      • Abdominal pain
      • Stomach pain

      We’ll go into more detail on the symptoms of different types of non-IgE-mediated food allergies below.

      Types of Non-IgE-Mediated Food Allergies

      Some types of non-IgE-mediated food allergies include:

      • Food protein-induced enterocolitis syndrome (FPIES)
      • Food protein-induced allergic proctocolitis (FPIAP or allergic proctocolitis)
      • Eosinophilic esophagitis (EoE)

      Food protein-induced enterocolitis syndrome (FPIES) is a rare type of food allergy. It usually appears in babies. Any food could cause an FPIES reaction, but milk, soy, oats and rice are common triggers.

      FPIES usually causes vomiting around 2-4 hours after baby eats the food they’re allergic to, and can also cause diarrhea. The vomiting and diarrhea can sometimes be severe, which can cause baby to become pale, feel floppy and become dehydrated.

      If your baby experiences severe vomiting or diarrhea, take them to a doctor right away so they don’t develop shock. If baby does develop shock from severe FPIES symptoms, seek immediate emergency attention.

      Food protein-induced allergic proctocolitis (FPIAP or allergic proctocolitis) causes inflammation in the lower part of the intestine when a baby eats a food they’re allergic to. Usually, this allergy will be to cow’s milk or soy, and will appear in babies under one year of age.

      FPIAP usually causes baby to pass abnormal stools that are bloody, watery, or filled with mucus. It can also cause diarrhea, anemia, vomiting, and fussiness.

      Eosinophilic esophagitis (EoE) causes eosinophils, white blood cells associated with allergies, to build up in the esophagus. This causes baby's esophagus to become inflamed, which makes it difficult and painful for baby to swallow food. Common food triggers of EoE include milk, egg, wheat, and soy.

      Symptoms of EoE in babies can include vomiting, irritability, problems with feeding, decreased appetite, chest pain, abdominal pain, reflux-like symptoms, and difficulty gaining weight.

      Non-IgE-Mediated Food Allergies: Severity

      Non-IgE-mediated food allergies usually don’t cause severe allergic reactions, and are very rarely life-threatening. Reactions caused by this category of food allergy hardly ever require epinephrine (an Epi-pen injection).

      But rarely, babies with FPIES who develop severe vomiting and diarrhea can develop shock. Shock occurs when baby’s body isn’t getting enough blood flow, and requires immediate emergency treatment.

      Also, a baby with a delayed-type food allergy could still develop a more severe food allergy.

      People with a non-IgE-mediated food allergy can also develop an IgE-mediated food allergy, and have both types of allergies at the same time.

      And any allergic reaction involving an IgE-mediated food allergy has the potential to be severe (or even life-threatening).

      Diagnosing Non-IgE Mediated Food Allergies

      Non-IgE-mediated food allergies can be difficult to diagnose.

      Skin prick tests or blood tests are usually used to diagnose food allergies. But these tests cannot diagnose a non-IgE-mediated food allergy, because these tests are used to see if someone is producing specific IgE antibodies for a certain food.

      There is no allergy test available that can accurately diagnose a non-IgE-mediated food allergy.

      The only way to possibly diagnose a non-IgE-mediated food allergy is to remove the food that you think is responsible for the allergy from your baby’s diet. (Talk to your doctor before removing a food from your baby's diet).

      Remember that with non-IgE-mediated food allergies, it can take up to 3 days for symptoms to appear, so you’ll need to remove the food from baby’s diet for several days. If you’re breastfeeding, you’ll also need to remove that food from your own diet, since the food could be passed to baby through your breastmilk.

      For example, if you think that cow’s milk is causing the symptoms, stop feeding baby milk for several days, and stop consuming milk if you’re breastfeeding

      Then, see if the symptoms improve after you’ve removed the food. After that, reintroduce the food back into your baby’s diet and see if the symptoms reappear.

      If your baby’s symptoms improve when you remove the food, but then reappear once the food is reintroduced into their diet, they may have a non-IgE-mediated food allergy. But their symptoms might have stemmed from a food intolerance instead.

      Non-IgE Mediated Food Allergies Vs. Food Intolerances

      Many babies are misdiagnosed with non-IgE-mediated food allergies, because non-IgE-mediated food allergy symptoms are similar to the symptoms of a food intolerance.

      For instance, some parents think their babies have a non-IgE-mediated milk allergy, when their baby really has a milk intolerance.

      If you remove a food from baby’s diet and their symptoms improve, your baby might have a non-IgE-mediated allergy to that food, but not necessarily. They could also potentially have an intolerance to that food, which is not the same as an allergy.

      Food intolerances are different from food allergies. Food allergies involve the immune system, but food intolerances do not involve the immune system.

      Managing Non-IgE-Mediated Food Allergies

      There is no cure for non-IgE-mediated food allergies. To manage these food allergies, you’ll need to figure out which food (or foods) could be causing the allergic reaction, and remove the troublesome food(s) from your baby’s diet.

      However, non-IgE-mediated food allergies can be outgrown, and often are.

      • If a baby has FPIAP, they’ll usually outgrow it by one year of age.
      • Children with FPIES often outgrow it at or around 3 years of age, and will almost always outgrow it before adulthood.
      • EoE is not outgrown as often, but it can still resolve on its own. (We still need more information on why some people outgrow EoE and others don’t, and on when it’s usually outgrown.)

      Reintroducing Foods to Babies with Non-IgE-Mediated Food Allergies

      If your baby has a non-IgE-mediated milk allergy (or a milk intolerance, which often produces similar symptoms), doctors typically recommend reintroducing milk into baby’s diet at some point. So, if you’ve already removed cow’s milk from your or your baby’s diet, talk to your pediatrician or allergist about when to reintroduce it.

      If you think your baby has a delayed-type food allergy to another food, and you’ve removed that food from your diet, you should also talk to your doctor about adding that food back into baby’s diet. This is especially important if the food is a common allergy-causing food.

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      All health-related content on this website is for informational purposes only and does not create a doctor-patient relationship. Always seek the advice of your own pediatrician in connection with any questions regarding your baby’s health.

      These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease.  If your infant has severe eczema, check with your infant’s healthcare provider before feeding foods containing ground peanuts.