How to Test Children for a Suspected Milk Allergy

Written by Registered Dietitian Nishti

We are often asked how to test children who may have a cow’s milk protein allergy—or an allergy to other foods.

Before we get into testing, it’s essential to understand the type of allergy we’re dealing with. There are two main types of cow’s milk allergy:

• IgE-mediated (immediate reaction)

• Non-IgE-mediated (delayed reaction)

Each type presents with different symptoms and requires a different approach. If you're unsure which one applies to your child, read this blog post first for a full explanation of the differences.

Validated Tests for IgE-Mediated Allergies

Testing can be helpful—but only for IgE-mediated allergies. Even then, tests alone cannot confirm a diagnosis. A detailed allergy-focused history taken by a qualified healthcare professional is essential and always comes first.

There are only two validated tests for IgE allergies:

• Skin Prick Test (SPT): Results in around 20 minutes.

• Specific IgE Blood Test (sIgE): Results in a few days.

A larger wheal size on an SPT usually means a higher chance of an allergy—but importantly, it doesn’t predict the severity of a reaction.

📺 Watch: I explain more about allergy testing in this ITV News clip.
📺 Also see: My full video with Dr Costa, where we break down exactly which tests are reliable—and which ones to avoid.

Why Testing Doesn’t Work for Delayed Allergies

If your child has a non-IgE (delayed) allergy, testing is not helpful. There are no validated tests for this type of allergy.

The gold standard for diagnosing delayed allergies is an elimination and reintroduction trial:

1. Remove cow’s milk protein from the diet for 2–4 weeks.

2. Observe if symptoms improve.

3. Reintroduce milk and watch for return of symptoms.

This is the only reliable method to identify a non-IgE allergy.

What Allergy Tests Can—and Can’t—Tell You

✅ Tests can help identify the likelihood of an IgE-mediated reaction.
❌ Tests cannot predict how severe a reaction will be.
❌ Tests cannot detect non-IgE (delayed) allergies.

A Word of Caution About Online Allergy Tests

We understand the frustration when you're looking for answers—but please don’t waste your time or money on unvalidated online allergy tests, hair analysis, kinesiology, or IgG tests for food intolerance.

👉 These are not scientifically supported, especially for diagnosing non-IgE allergies.

We break this down fully in our video with allergy consultant Dr Costa—click here to watch it and get clarity on what really works.

If Your Child Has Immediate Reactions

If your child shows signs of an immediate reaction after eating milk or other foods—such as:

• Hives or swelling, vomiting, breathing difficulty, wheezing or coughing within minutes

They must be referred to a consultant in allergy as soon as possible. This type of reaction could be life-threatening and must be taken seriously.

References

• Fox, A., Brown, T., Walsh, J. et al. (2019). An update to the Milk Allergy in Primary Care guideline. Clin Transl Allergy, 9, 40.

• Luyt D, Ball H, Makwana N, et al. (2014). BSACI guideline for the diagnosis and management of cow’s milk allergy. Clin Exp Allergy, 44(5), 642–672. 

• Vandenplas, Y. et al., 2024. An ESPGHAN position paper on cow’s milk allergy. J Pediatr Gastroenterol Nutr, 78(2), pp.386–413.