Explanation

Your doctor may do an allergy test to find out if you are allergic to a type of food, or to other things like pets, dust mites and pollen. There are a few different allergy tests that you could have.

Skin tests, like the skin prick test, are the ones that are most often done. You could also have a blood test, or, if your doctor thinks you have a food allergy, an elimination test.

There are other allergy tests too, your doctor will choose the one that is best for you.

Why do I need one?

If you are allergic to something, it can make you feel quite unwell. You may get headaches, a runny nose, itchy red skin, and maybe a rash, as well as indigestion or many other problems.

Some serious allergic reactions may lead to anaphylaxis, so it's important for your doctor to find out if you're allergic to anything.

What happens before I have it?

Your doctor will chat with you about your lifestyle, what food you eat and what illnesses you have had in the past, before he or she decides to do an allergy test.

Before you have your allergy test, you should make sure you don't take any Anti-histamines, and make sure you tell your doctor about any other medicines you're taking as well.

How is it done?

If you have a skin prick test, the allergens that the doctor thinks may be causing your allergy (like pollen and animal dander) are each mixed with a liquid. A tiny droplet of each mixture is then put onto your skin - usually on the underneath of your forearm. You may have up to 10 or 12 droplets of different mixtures put on your arm, depending on how many allergens your doctor thinks could be causing your allergy.

The skin underneath each drop is then pricked with a needle. Don't worry, it doesn't usually hurt at all - only the very surface of your skin is pricked, just enough to let a tiny amount of each mixture into your skin.

If you have an elimination test, your doctor will tell you to stop eating foods that he or she thinks you may be allergic to. You eliminate them from your diet for a few weeks. After the few weeks are up, you will then need to start eating these foods again, one at a time, and see if you have an allergic reaction to any of them.

Your doctor can also do a blood test to see if you are allergic to anything. Blood tests are used to measure the number of antibodies or white blood cell in your blood. This can give your doctor enough information to see if you are allergic to something.

Will it hurt?

Most allergy tests don't hurt at all. Skin tests tests may make your arm red and itchy for a short time, though.

If you are on an elimination diet test, you may have an allergic reaction to some foods, which may feel uncomfortable.

What happens next?

If you have a skin prick test, you and your doctor will watch your skin to see if you get an allergic reaction to any of the mixtures. If a reaction occurs, it happens within 20 and 30 minutes. If your skin gets red and itchy under a drop of mixture, this is a positive reaction - you are allergic to the allergen in the mixture. You may also have a white, raised swelling - this is called a weal.

Your doctor will give you some anti-histamine cream to put on your skin to stop the itching, and help any weals to disappear quickly.

If your skin stays normal, this is a negative reaction - you are not allergic to the allergen in the mixture.

If your allergy test has shown that you are allergic to anything, your doctor will talk to you about how to best avoid the allergen or allergens that you are allergic too. He or she might also give you some anti-histamines to take.

What if I have any other questions?

If you have any other questions, you can ask your doctor, or chat to other people about allergy tests in the Medikidz forums and virtual world, Mediland.