Food Allergies: Diagnosis

This information was reviewed and approved by Bruce J. Lanser, MD, MPH (7/31/2015).

Every diagnosis begins with a detailed medical history and physical examination. The doctor will ask many questions about the nature of the reaction, where and when it occurs, which foods are thought to cause symptoms, etc. You may be asked to keep a detailed food diary to help in making the diagnosis. Since the possibility to become allergic is inherited, expect some questions about other family members who may be allergic.

Transcript

A food allergy is a type of adverse reaction to foods, and it triggers a cascade of reactions that involve a flare for your immune system.

About 8% of children have true food allergies, whereas in the adult population it's about 2.5%.

The most common childhood allergies are eggs and milk, and those are typically outgrown by late teenage years.

There are certain foods, such as peanuts, tree nuts, shellfish, those are rarely outgrown.

Allergic reactions to foods typically is immediate.

These reactions can cause hives, swelling, nasal congestion, runny nose, feeling that your throat might be closing in.

It can also potentially be life threatening.

Testing for food allergies can be done either via skin testing or blood testing.

Both look for the specific IgE to that particular food.

The gold standard is what we call an oral food challenge.

An oral food challenge is when we take a particular food, like peanuts, and we give you increasing doses of the egg to document whether you can tolerate the food or not.

To treat an allergic reaction, it depends on what type of allergic reaction you're experiencing.

If it's just hives scattered on the face or your body, without it developing into anything more, you can take an oral antihistamine.

If you are having more than one body system, so hives plus difficulty breathing or difficulty breathing plus nausea and vomiting, you're going to want to use an epinephrine auto injector immediately and go to the emergency department.

Anybody who has a known food allergy should carry an epinephrine auto injector on themselves at all times.

You never know when you're going to be accidentally exposed.

Being able to use the epinephrine auto injector can be life- saving.

Depending upon the findings of the initial evaluation, the following tests may be necessary:

Allergy skin testing may be performed to check for sensitivity to selected food allergens.
Blood testing is often indicated.
A food diary may be necessary to record what was eaten, when it was eaten, how long after eating a reaction occurred, what was the reaction and what treatment was given.
Food challenges, which are done with safety as the highest priority, may be performed as well. Learn reasons to do food challenges.

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