Skin testing is a very common and reliable test to determine your child’s allergies in about 15 to 20 minutes. Small amounts of liquid that contain different allergens (food or environmental), are applied on the surface of the skin (forearm or upper back) with a small scratch. If a positive reaction appears it will itch and is similar to a mosquito bite with a bump and redness. Fifteen minutes after the tests are placed the allergy provider will measure the red bumps with a clear ruler and the itch will slowly go away over the next 30 – 45 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 antibody, 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.
Graded Oral Food Challenge
This is a test to find out whether a person is allergic to a food. The food challenge is done in the Allergy Clinic or in the hospital. Medicines are ready to reverse a reaction if it occurs, and the doctor and nurse watch 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 is 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.
Oral immunotherapy (OIT) is a process of building up tolerance to a food your child is allergic to. The goal of OIT is to decrease your child’s sensitivity to the allergic food. By slowly introducing the allergic food it may lower the risk of life-threatening allergic reactions if the child is accidently exposed. The process is also known as desensitization.
The first step in this process is to find a safe starting amount of the allergic food for your child, this visit is called an Initial Escalation. During your clinic visit, the doctor will identify the right dose your child can tolerate without having allergy symptoms. Your child will then take this small amount of the food every day at home. The dose slowly increases at clinic visits every two to four weeks until set serving amount is reached. These visits are called up dose visits..
Your child is a good candidate for OIT if:
- We can find a safe starting dose of the food allergen for your child.
- They can cooperate with eating the food every day.
- You are willing to make sure your child gets their dose of the food allergen every day.
- You can come for clinic visits every two to four weeks for roughly six months or longer, depending on how the process goes with your child.
Drug Allergy Testing
For patients suspected to have a medicine allergy, allergy skin testing is sometimes helpful to see whether they are allergic to the medicine. In many cases, an oral dose of the medicine is given to see 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. The medication challenge can be a single dose or gradual dosing depending on the medication and the child’s history of reaction. The physician and nurse watch the patient carefully, and medicines are available to reverse any reaction that occurs.
Pulmonary Function Testing
This testing measures how well the lungs are working. Pulmonary function testing is often done 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.