Skin prick test

This is usually the first test that you will have if your doctor suspects that you have an allergy. 

You might be able to have this test done at your GP’s surgery or you may have to go to the hospital to have it done. You will be asked to stop taking ant-histamine medication a few days before your test (your doctor will give you further advice about this).

What happens

The skin prick is usually done on the inside of your forearm.

The doctor or nurse will choose some allergens (substances that may cause an allergic reaction) which may be causing your allergy. Up to 25 allergens can be used, though it may be only a few.

The doctor or nurse will mark your arm using a waterproof pen so that he or she can easily identify which allergen is which. Then he or she will place a drop of each allergen next to the marks on your arm.

You will then be given a small scratch to your skin through the middle of each drop. If you are allergic to any of the allergens your skin may become itchy and you may get raised bumps (like nettle stings). Within 15 to 20 minutes the bump will increase to its maximum size.

Once the procedure is completed it will only take around 20 minutes for the reaction to take place. Then you will see the doctor or nurse again before you go home.

Does it hurt?

It will probably be uncomfortable but shouldn’t actually hurt you.


The doctor or nurse will be able to tell you the results before you leave.

NB. Although the skin prick test is safe for most people with allergies as only a very small amount of allergen is used if you have experienced anaphylaxis before it might not be suitable for you. Please discuss this with your doctor.

Compiled by:
Great Ormond Street Hospital
Last review date:
January 2014