How to confidently identify true pediatric food allergies, avoid unnecessary testing, and support families with evidence-based care.
You’re in clinic. A worried parent tells you their toddler vomited after eating avocado and wants “a full allergy panel.” Or maybe you're handed a thick stack of food allergy results showing a handful of “abnormal” findings and asked what to do next. Sorting out true pediatric food allergy from food intolerance — or something else entirely — is a common challenge in primary care.
Here’s the good news: most food reactions in children are not true allergies. And with a systematic approach, you can feel confident knowing when to test or refer, when to reassure, and when to hit pause on that elimination diet.
For an even deeper dive, we break this down with pediatric allergist Dr. Neema Izadi on our Peds Reviews and Perspectives episode, "Allergy Testing Part One", including testing pitfalls and practical strategies for primary care.
Let’s start with a quick refresher.
A food allergy is an adverse immune response to a food protein. It’s most often IgE-mediated (think: hives, anaphylaxis) and can be life-threatening. These reactions are:
Immediate (usually within 30 minutes, occasionally up to 2 hours)
Reproducible (occurs with every ingestion)
IgE-mediated symptoms: hives and vomiting are the most common, but symptoms can range from a runny nose and scratchy throat to difficulty breathing and anaphylaxis
Food intolerance in children, on the other hand, is a non-immune response, often due to enzyme deficiencies (like lactase), sensitivity to proteins (like gluten), or gut immaturity. Symptoms can include bloating, gas, or diarrhea.
And sometimes, it’s neither. A patchy rash after a meal can be a sign of enthusiastic and messy eating, causing irritation. An episode of vomiting might just mean a toddler needs to wait a little longer after meals before trying out a new dance routine.
This is a big one. IgE testing only tells you whether someone is sensitized to a food; it doesn’t tell you whether they’ll actually react. That’s why large food panels, online IgG tests, or testing without a good history can do more harm than good.
Avoid IgE testing for:
Non-IgE conditions like:
Food Protein-Induced Allergic Proctocolitis (FPIAP, formerly known as milk protein intolerance)
Lactose intolerance
Celiac disease
Food Protein-Induced Enterocolitis Syndrome (FPIES) (note: when you’re unsure if vomiting is FPIES vs IgE-mediated allergy, it’s reasonable to send an IgE to help clarify)
Chronic symptoms like:
Abdominal pain
Eczema
Allergic rhinitis without a clear link to food ingestion
Chronic spontaneous urticaria (lasting days to weeks, unlike typical IgE-mediated hives)
Overtesting risks are not to be underestimated. The diagnosis of food allergy is a huge burden to children and families. False positive results can lead to:
Malnutrition and growth issues, from avoidance of major food groups.
Psychological burden from restrictive diets, social limitations, and anxiety.
Increased risk of acquiring IgE-mediated food allergy if infants avoid foods unnecessarily and miss the early introduction window for risk reduction.
Financial burden of healthcare costs from increased testing, specialty appointments, missed work and school. This can disproportionately affect minority families, leading to wider healthcare disparities.
If the clinical story fits — immediate, reproducible, IgE symptoms — then yes, order an IgE test. But only for the specific food in question.
Key testing tips:
A negative IgE (<0.35) has strong negative predictive value
A positive test only shows sensitization — not clinical reactivity
Very low positive numbers (like 0.10 or 0.15) are clinically insignificant, even if flagged “high” on lab reports
Avoid multi-food allergy panels, which have high false positive rates
Let’s dig in a little deeper into the concept that a positive IgE reflects sensitization, not reactivity. As much as we wish the labs were crystal clear, they often aren’t. A positive IgE result doesn’t always mean a true allergy. If a child eats the food without symptoms, they are not allergic — regardless of the number on the lab slip. False positives are especially common in children with atopic dermatitis, since their IgE levels are globally elevated.
In an oral food challenge (OFC), a patient is offered a small amount of the suspected food in a controlled environment and observed for reactions.
Is this needed for the baby who broke out in hives after peanuts? Usually no. But a child who vomited after scrambled eggs? A food challenge with an allergist might be helpful to figure out if it was a texture issue or an IgE-mediated allergic response. Or to tease out if eggs are tolerated in baked form. This is when our lovely local pediatric allergist comes into the picture.
The decision to refer to a pediatric allergist often depends on your local resources, wait times, and patient complexity. In general, refer to a pediatric allergist when:
There’s a clear IgE-type reaction with a common or high-risk food (peanut, tree nut, egg, milk, fish, shellfish)
You need help interpreting complex results
An oral food challenge is appropriate or requested
There’s concern about cross-reactivity (e.g., shellfish types or tree nuts)
A few clinical pearls I got from my conversation with Dr Izadi:
Seafood: Fish and shellfish allergens are not related. Don’t assume a fish allergy = shellfish allergy.
Tree nuts: If a child reacts to one, you can test for others (hazelnut, cashew, walnut). But if they’re eating a nut already, don’t take it away.
Oral allergy syndrome: Mild oral itching from raw fruits/veggies in older kids often reflects pollen cross-reactivity — not true allergy. No need for food IgE testing; evaluate environmental allergies instead.
Parents often want to "try cutting it out" to see if things improve. While that instinct is understandable, broad elimination diets can be harmful without clear justification.
Risk of nutritional deficiency (especially in growing children)
Lead to loss of tolerance, potentially triggering new IgE allergy
Creates anxiety, food fear, and social challenges
Reserve elimination strategies for guided settings with Allergy or Gastroenterology support.
Food reactions can be stressful for families, but your thoughtful guidance makes a big difference. By narrowing testing to true allergy suspicion and avoiding unnecessary eliminations, you help kids stay nourished, safe, and confident at everyday social gatherings.
For a deeper dive into pediatric food allergy testing, tune into my conversation with Dr. Neema Izad, “Allergy Testing Part One ” on the Peds Reviews and Perspectives podcast.