What is a Skin Prick Test?

A skin prick test is a diagnostic test performed for the purposes of identifying allergies in a patient. The test involves the careful introduction of potential allergens to a patient in a controlled environment, with monitoring for reactions. The outcome of the test can be used to confirm an allergy diagnosis, to rule out potential allergens as causes for a health problem, and to provide guidance for treatment of the patient. This test is usually performed by an allergy specialist.

In a skin prick test, very small doses of allergens are introduced into patches on the patient's skin. Allergy testing is often performed on the back because it provides a large canvas for the testing. The doctor notes the location of each allergen and then skin reactions are carefully monitored. If there is a skin reaction, the characteristics are noted. Reactions indicate that the patient is reacting to the allergen and the size and color of skin lesions can indicate the severity of the allergy.

Skin prick testing is relatively safe for patients. Only small doses of allergens are introduced to avoid inducing anaphylaxis, and if the patient has a history of anaphylactic reactions to unknown allergens, the doctor will use measures other than skin prick testing to determine the nature of those allergens. Just in case, the patient is usually required to stay in a clinical setting long enough to determine whether a very strong reaction will occur so that medical aid can be provided if the patient has an extreme reaction.

A doctor will usually ask for a food and activity diary to narrow down potential allergens before recommending a skin prick test. The patient may also be asked about a family history of allergic reactions and will be asked for detailed information about any allergic reactions experienced. This information will be used to generate a list of potential allergens for testing. If there are a lot of allergens, the patient may need several skin prick tests, because the doctor doesn't want to site test patches so closely together that it will be hard to determine what the patient is reacting to.

This test can be uncomfortable. The pricking of the needle used can be painful and if the patient experiences a reaction, the skin will be tender and later itchy for several days. It is advisable to set aside several hours for a skin prick test so that the patient will have time to complete the test, be monitored, and rest at home afterward. If a patient notices any symptoms of a severe reaction after a skin prick test at home, a doctor should be notified immediately.