Knowing if a Food Allergy is Anaphylactic

The common refrain about food allergies is “any food allergy can result in anaphylaxis. A previous reaction does not predict a future reaction.” 

But this is not technically correct. 

It depends on what you mean when you say “allergy.” Not all allergies are the same. They are all serious, but some can have deadly consequences while others don’t. 

Especially when it comes to milk and wheat, many children will be diagnosed with a food allergy, but it is not the same as an anaphylactic allergy. Knowing the difference is important because it will guide how you navigate life after a diagnosis. 

The Three Types of Food Allergies

There are three types of food allergies -- IgE-mediated, Non-IgE-mediated, and mixed IgE non-IgE. The three types of food allergies have overlaps but knowing the differences can help you know how careful you need to be.

Types of Allergy	IgE Mediated	Non-IgE	Mixed IgE Non-IgE
Diagnosis	Anaphylactic allergy	FPIES, enteropathy, proctitis, proctocolitis	Atopic dermatitis, Eosinophilic Esophagitis (EoE)
When it develops	First 3 years	First year	First year
Time to  symptoms	Seconds to 4 hours	Often after 4 hours	Feels almost unrelated to when food was eaten
Skin Symptoms	Hives. Also maybe redness, swelling	Herpes-like patches	Chronic eczema, especially with “raw” skin
GI symptoms	Pain, vomiting, diarrhea	Diarrhea, watery stools (FPIES) or mucus or blood in stool (proctitis)	Can’t swallow, projectile vomit, pain
Airway Symptoms	Coughing, sneezing, tightening of airways	Not common	Not common
Time to symptoms resolving	Immediate after medication	Weeks, months	Weeks, months
Need EpiPen?	Yes	No	No
Treatment	Strict avoidance, immunotherapy	Remove from diet	Remove from diet

IgE Mediated Food Allergy

IgE-mediated allergies are the “anaphylaxis” allergies most commonly discussed. IgE allergies  can develop at any age, but most develop in early childhood when the immune system is learning. 

Reactions come on fast, usually within seconds or minutes of eating a food, and almost all reactions happen within 4 hours, though it is possible for them to be delayed. The symptoms of IgE allergies are sudden hives, redness of the skin, stomach cramping & pain, vomiting, diarrhea, coughing, sneezing, closing of the airways, and fever.

IgE mediated allergies are set-off by IgE antibodies and can be tested for in a doctor’s office with skin-prick, or blood testing. 

Non-IgE Mediated Food Allergy

Non-IgE mediated allergies are most commonly diagnosed in small babies. Symptoms are usually limited to the stomach, though some herpes-like eczema patches also happen. 

You may have heard this group of allergies called FPIES (food-protein induced enterocolitis syndrome), enteropathy, proctitis, or proctocolitis. Different antibodies, including IgA and IgM, which are found in the mucus lining of the GI system, react to food proteins. Enterocolitis can happen anywhere in the gut, enteropathy in the small bowel, proctitis in the rectum, and proctocolitis in the colon. 

Symptoms from Non-IgE mediated allergies are usually delayed 4 or more hours after a food is eaten. Breathing symptoms and hives are rare. The most common symptoms are diarrhea, watery stools, or blood or mucus in stools, along with belly pain. The skin is sometimes involved with herpes like raised patches. 

The symptoms from Non-IgE mediated allergies can take days or weeks to go away even after the food is removed.

We do not have good tests for Non-IgE mediated allergies and these allergies will not show up on IgE testing. Doctors use symptom history to diagnose them. By the time a baby is diagnosed, they may have been eating that food every day for weeks or months. 

Technically, you can have a Non-IgE mediated allergy to any food, but they seem to be most common to milk, wheat, rice, oat, and other grains. 

Mixed IgE / Non-IgE Food Allergy

Because nothing is easy, there are also Mixed IgE & Non-IgE food allergies. They cause chronic eczema and Eosinophilic Esophagitis (EoE). As the name suggests, the symptoms are triggered by a combination of IgE cells and other immune cells, like eosinophils. 

Although there is still debate on this matter, a large and growing group of doctors agree that some eczema can be triggered by an underlying food allergy. The symptoms are limited to the skin which develops eczema patches that do not heal with steroids. EoE is limited to esophagus issues like pain when swallowing and projectile vomiting like the food can’t even make it into the stomach. 

Because there are IgE cells involved in these allergies, skin-prick or blood testing will show IgE antibodies. But a lot of people have IgE antibodies with no symptoms and no anaphylaxis symptoms, so from there doctors look to an elimination diet. 

The best diagnosis is when removing the food from the diet makes the eczema or EoE heal, and re-introducing the food makes the eczema or EoE flare again.

How to Move Forward

If your baby is experiencing any stomach or skin problems that make them cry, lose sleep, or fail to gain weight, it’s time to talk to your doctor, and possibly a registered dietician about figuring out what is going on. If you are breastfeeding, our friends at Freetofeed have great resources for how to eliminate foods from mom’s diet and then reintroduce a healthy, balanced diet.