IgE vs Non-IgE Food Allergy- What’s the Difference?
All your questions answered about the different types of food allergy. Written by Registered Baby and Child Dietitian, and Milk Allergy Specialist, Christina Hills.
Food allergies can be confusing- especially when your baby is reacting to something and you’re trying to work out why. You might have heard your doctor or dietitian mention IgE or non-IgE food allergies- but what do these terms actually mean, and how can you tell which one your child has? Lets have a look…
What Do “IgE” and “Non-IgE” Mean?
Both types of food allergy involve the immune system reacting to a food protein — but the timing, symptoms, and type of immune response differ.
IgE stands for immunoglobulin E, which is a specific type of antibody made by the immune system.
Non-IgE allergies involve other parts of the immune system (not IgE antibodies), and symptoms usually appear later.
Understanding which one your child has is important, because it changes how the allergy is diagnosed and managed.
IgE-Mediated Food Allergy (Immediate)
This type of allergy happens quickly- usually within minutes and up to 2 hours after eating or drinking the food.
It’s caused by the immune system producing IgE antibodies that recognise a food (like milk, egg, peanut or tree nuts) as harmful.
These antibodies trigger the release of histamine and other chemicals, which cause immediate allergic symptoms such as:
Hives or red, itchy skin
Swelling (around the eyes, mouth or face)
Vomiting or abdominal pain
Coughing, wheezing, or difficulty breathing
In rare cases, anaphylaxis- a severe, potentially life-threatening reaction
Because IgE-mediated reactions can be severe, diagnosis often involves allergy testing (like skin prick or blood tests) and should always be managed under the guidance of an allergy specialist.
Non-IgE-Mediated Food Allergy (Delayed)
Non-IgE allergies are a little trickier to spot- and are often confused with reflux, colic or another feeding intolerance.
Symptoms tend to appear hours or even days after the food is eaten, because the immune response works differently.
Common signs can include:
Tummy pain, wind or discomfort
Reflux, vomiting or frequent spitting up
Diarrhoea or constipation
Mucus or blood in stools
Eczema or persistent dry skin
Poor sleep or feeding aversion
Diagnosis for non-IgE allergies relies more on your child’s symptoms and history rather than lab testing. A dietitian will usually suggest a structured trial elimination and reintroduction- removing the suspected food allergens for a few weeks, then carefully reintroducing them to see if symptoms return.
Can a Child Have Both IgE and Non-IgE Mediated Food Allergy?
Yes - some children have what’s called a mixed allergy, meaning they can experience both IgE and non-IgE symptoms.
For example, a child might develop constipation (a delayed reaction) and vomiting or hives (an immediate reaction) after eating the same food.
This is why it’s so important to work with a specialist paediatric dietitian or allergy team who can interpret the pattern of symptoms and guide you through safe diagnosis and management.
What Happens Next?
Once a food allergy is confirmed, your dietitian will help you create a safe, balanced diet that avoids the trigger food but still meets your child’s nutritional needs.
For most children, food allergies don’t last forever - many will outgrow them during early childhood, though every child is different. When the time is right, your dietitian may guide you through a food challenge or reintroduction (milk ladder) under supervision.
Feeling overwhelmed?
If you’re reading this feeling unsure or overwhelmed- please know you’re not alone.
As a paediatric dietitian, I help families move from confusion to clarity, providing calm, evidence-based nutrition guidance. Together, we can find the right path forward for your child’s health and your peace of mind.
✨ Explore more in the Milk Allergy Hub or Book a 1:1 consultation for tailored support.