- A drop of a solution containing the allergen is placed on the skin of the forearm and then the skin is very finely punctured through the drop. Numerous allergens can be tested simultaneously using this test. The results are read in 15-20 minutes. A swollen, red, itchy reaction at the puncture site is usually an indicator of a positive response. If the tests are negative (no reaction appears at the puncture site) the test allergen can be ruled out as the cause of your symptoms. However, a positive test result does not necessarily mean that your symptoms are caused by that allergen. The meaning of a positive reaction is that you have the potential to develop allergy to that allergen (your body is producing IgE antibodies which react to that specific allergen). There are a lot of people who, if tested, would show positive reactions to a range of allergens without ever having had any symptoms when coming into contact with them. (If you want to know how this is possible please read the section What is allergy –Sensitization). A positive result must be interpreted in relation to the clinical history and other test results that the doctor might have performed on you. Typically, a positive test is followed by more detailed investigations. This is why it is unwise to try to make your own diagnosis using commercially available home allergy tests -. you might come to the wrong conclusion!
- In some cases the skin prick test cannot be performed. However the doctor can still check if you are producing IgE antibodies against a particular allergen by measuring them in your blood. He will have to take a blood sample from you to perform this test. As with the skin prick tests, a negative result practically rules out an allergy to the allergen in question whereas a positive test may implicate the allergen as being responsible (at least in part) for your symptoms.
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Diagnosis > Prick test
Skin Prick Tests