Skin Prick testing (SPT) is an accurate way to test possible allergic substances to see if they cause an allergic reaction. It can be used to test for food and aeroallergen (substances in the air e.g. pollen) allergies.
In some cases, diagnosis can be made based on the clinical details and a SPT is not required to make a diagnosis.
Most SPTs are carried out using commercially prepared liquid allergens. If you think you have been asked to bring a food, beverage or substance to clinic for skin testing then this should not be mixed with any other products, for example sauces. It should also be individually packaged. For example, bring a whole piece of fruit rather than a pre-prepared fruit salad. If the food is usually eaten cooked, such as chicken, please bring a cooked sample.
Diagnosis of food allergy may be possible in a single clinic visit. In some cases however it may be necessary to wait for blood tests and/or to carry out an oral challenge with the food. This involves consumption of a food in increasing amounts, in a controlled environment, with medical supervision.
Skin prick testing is carried out on the inner forearm as follows:
1. A small amount of the allergen solution liquid is dropped onto the skin
2. The location of each droplet is marked on the skin with a pen and the skin under the drop of allergen is then pricked with a lancet. This is felt as a small scratch or prickle and is not usually painful

3. The droplets are blotted away with a tissue

4. The skin prick test will start to work immediately and may cause itch or irritation to the skin. It is important that you do not scratch the test area as this can make the test difficult to interpret.
5. After approximately 15 mins the nurse or doctor will be able to read the test result on the skin. Positive results appear as a small itchy wheal on the skin which can be measured with a ruler and recorded in the medical notes

Following the skin-prick testing the doctor or nurse will interpret the test results and explain these to you.
Diagnosis
It is often possible to make an allergy diagnosis during the first clinic appointment but sometimes it may be necessary to wait for blood test results and/or to refer you on to a further clinic for more testing.