Allergy Diagnostic Procedures

Diagnostic tests for allergy may include any of the following:

Skin testing is a very common and reliable test to determine your child’s allergies. Using small amounts of solution that contain different allergens, your child's doctor will either inject under the skin or apply the allergens on the surface of the skin with a small prick. A positive reaction will appear as a small red area at the site of the test in about 15 minutes. A reaction to the skin test does not always mean your child is allergic to the allergen that caused the reaction. Your child’s doctor will determine this.  However, a non-reactive skin test is a reliable sign that your child is NOT allergic to that substance.

Blood tests for allergies measure the antibody that causes allergic reactions, called IgE antibodies, to specific allergens in the blood. The blood test most commonly used is called ImmunoCAP. Blood tests may be used when skin tests cannot be performed, or in addition to skin tests to give further information about the allergies. As with skin testing, it is important to remember that a positive blood test does not always mean your child is allergic to that allergen.

This is a test that is done to find out whether a person is allergic to a food.  The food challenge is done in the Allergy Clinic or in the hospital. Medications are ready to reverse a reaction if it occurs, and the physician and nurse monitor the patient carefully.  The challenge starts with a very small amount of the suspected food allergen, and the patient is observed for a period of time.  If there is no reaction, a slightly larger amount of the food is given and the patient is again observed for any reaction.  The oral challenge proceeds until a full serving of food has been eaten, or until there is an allergic reaction.  It is rare for a severe allergic reaction to occur to an oral food challenge, because of the very small initial dose and very gradual increase in dose.  Food challenges are done if it is unclear whether a patient is allergic to the food in question, or when a previous food allergy seems to be resolving. 

For patients suspected to have a medication allergy, allergy skin testing is sometimes helpful to determine whether they are allergic to the medication.  In many cases, it is necessary to give a “test dose” of the medication to determine whether the patient is allergic to it.  This is done in the Allergy Clinic or in the hospital, depending on the nature of the previous reaction and the state of general health of the patient.  As with the graded oral food challenge, drug allergy test dosing usually starts with a low dose of the medication, and the amount is gradually increased if the patient has no reaction during a period of observation.  The physician and nurse monitor the patient carefully, and medications are available to reverse any reaction that occurs.   

This testing is done to measure how well the lungs are working.  Pulmonary function testing is done periodically for children with asthma, to monitor how well their asthma is controlled.  It is also done to diagnose asthma or other respiratory problems.  Children around 6 years old or older are usually able to perform pulmonary function testing. 

Last Updated 04/2015