Explanation

A skin prick test is a type of allergy test.

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. The skin prick test is one of the most common allergy tests you can have.

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 have a 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.

It's also very important to tell your doctor if you ever had anaphylaxis.

You may have this test at your doctor's surgery, or you may have it done in outpatients at a hospital.

How is it done?

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 doctor will mark your skin with a waterproof pen (a bit like tattooing!), so that he or she can remember which allergen droplet is where on your skin.

The skin underneath each drop is then pricked with a needle, to give the droplets chance to react with your skin. 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 it.

Will it hurt?

No. A skin prick test doesn't hurt, but it may feel uncomfortable.

What happens next?

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 more 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 areallergic 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 skin prick tests or other allergy tests in the Medikidz forums and virtual world, Mediland.