What is it?  

Skin prick testing, sometimes called scratch tests, is a series of tests that are done to find out what substances may be causing an allergic reaction.

These tests are considered the ideal method to diagnose potential allergies as they follow a safe and reliable process.       

What does it involve?  

Skin allergy tests are done by putting different allergens on the skin – normally on the forearm, although they can also be done on the back — after gently pricking the skin with a needle.    

After placing the allergen on the skin, and leaving it for a few minutes, the intensity or magnitude of the reaction will indicate if there is an allergy. So, these tests allow doctors to know if there is an allergy to pharmaceuticals (medications), pollen, mites, funghi, insect stings or bites, fabrics, cat and dog hair, and many other substances.   

These tests are generally carried out in a single appointment, and the patient only needs to be in the clinic around a couple of hours. The patient will be informed about the procedure, as well as all the potential reactions that could occur during the test, such as itching or hives at the test site.       

The test is normally done on the forearm, after cleaning the area with alcohol, when it has evaporated, a small amount of the allergen is placed in the skin.  

Different kinds of allergens will be tested and each prick will be about 2cm apart. So, once the allergen is placed on the skin, the technician will prick the skin so that the allergen can enter.     

The area that has been tested will be checked after about quarter of an hour to see the results of the tests.   

What is it for?

Skin prick tests are mainly used for diagnosing potential allergies by putting a drop of the substance that you may be allergic to on your arm. These tests not only help discover the cause of the allergy, but they can also determine the severity of the allergy.  

How can you prepare for it?

Skin prick tests are done in a clinic, it is a short test which should only take an hour or two.    

The patient should avoid taking medications, such as steroids or antihistamines, before the test as they could interfere with the results. These tests should not be carried out during pregnancy as they could cause reactions that may affect the fetus. 

What does it feel like during the procedure?

These tests are simple and the patient should hardly be able to feel them, although they will notice mild pricks which may feel itchy afterwards.