Food Allergy Testing

The UPMC Sino-Nasal Disorders and Allergy Center provides food allergy testing for common food allergens and intolerances.

Food Intolerance vs. Food Allergy

Doctors classify adverse reactions to food as either a food intolerance or food allergy.

The differences between these two are:

Food intolerance:

• Does not involve the immune system
• A dietary enzyme supplement often helps treat food intolerance 
• Lactose deficiency is a common example of food intolerance to dairy products. A lactase supplement can help address the problem. 

Food allergy:

• Involves the immune system
• The symptoms of a food allergy may be treatable, but the allergy itself may not
• In contrast, supplements can't correct an allergy to dairy products. 

Common Food Allergens

The eight most common food allergens cause more than 90 percent of all allergic reactions to foods.

These common allergens are:

• Milk
• Eggs
• Peanuts
• Tree nuts
• Soy
• Wheat
• Fish
• Shellfish

What We Test For

Food allergy testing involve testing for immunoglobulin E (IgE). Immunoglobulins are proteins, most of which help protect the body from infection.

IgE can be different.

In about 20 percent of humans, IgE reacts against substances that are harmless, such as:

• Pollen grains
• Animal dander
• Some food proteins

People who suffer from allergic asthma and allergic rhinitis (hay fever) are those whose IgE have an allergic reaction. This can cause allergic reaction symptoms of sneezing, swelling, redness, and itchiness.

Types of Food Allergy Tests

Experts at the UPMC Sino-Nasal Disorders and Allergy Center use a few types of food allergy tests for diagnosis of allergies.

Elimination challenge diets

An elimination diet — a vital part of diagnosing food allergies — tests reactions to foods that are not necessarily associated with high levels of IgE.

In the diet, you will not eat a certain food for five days. If you are allergic to the food, the period of withdrawal makes you more sensitive to it.

On the sixth day, you will eat a small portion of the withdrawn food.

Allergic reaction adverse symptoms — such as itching, gastrointestinal distress, facial pressure, or nasal congestion — mean that you are allergic to the food.

In vitro testing, including radioallergosorbent (RAST) tests

Doctors use in vitro food allergy testing to identify allergies in people who cannot have skin testing or who might have a life-threatening allergy, such as peanut anaphylaxis.

This method involves taking a blood sample to test for:

• What kinds of IgE are present.
• How much of each kind is present.
• How much of each kind applies to a certain tested food.

Skin tests

In a skin test, doctors place a small amount of a suspected allergen under the top layer of the skin on your upper arm.

If your skin reacts, this means you are allergic to the substance.

To make an appointment or to refer a patient, contact one of our Sino-Nasal Disorders and Allergy Center locations.

Make an Appointment

To make an appointment or refer a patient, contact the Division of Sino-Nasal Disorders and Allergy.

Learn More About Food Intolerance and Allergies

UPMC Patient Education Materials:

• Milk Doesn't Agree With You: Lactose-Restricted Diet

From our Health Library:

• Food Allergy
• Lactose Intolerance