What is an Allergy Skin Test?

An allergy skin test is a type of test performed on patients in order to determine which substances cause them to experience an allergic reaction. In this test, a patient's skin is exposed to allergens. The doctor then observes the skin to detect any signs of skin sensitivity to the substance. After determining which substances cause an allergic reaction in the patient, the doctor can plan a treatment method that may include allergy shots, medication, or allergen avoidance.

Patients who may be sensitive to certain substances are often given allergy skin tests. For example, those who have food allergies, bee sting allergies, allergies to certain foods, asthma, skin conditions, or hay fever can receive an allergy skin test in order to formerly diagnose these sensitivities. Before performing the test, the doctor will learn about the patient's medical history and other pertinent information about the patient.

The allergy skin test is performed in the doctor's office, usually administered by a nurse. There are three types of allergy skin tests performed on patients: the scratch test, the intradermal test, and the patch test. Both the scratch test and intradermal test use needles.

The scratch test, also called a puncture or prick test, is the most common form of allergy skin test. In this particular test, miniscule drops of liquid allergen extracts are pricked onto the surface of the skin. The test is used to determine if a patient has allergy to pollen, foods, dust mites, mold, or pet dander.

A second form of allergy test is called the intradermal test. In this examination, liquid allergen extracts are injected into the skin. This test is administered to a patient to determine if he or she is allergic to penicillin or insect venom.

Patch tests are allergy skin tests that do not involve the use of needles. The allergen is put on a patch and placed on the skin. A patch test is administered in order to determine if a patient is allergic to latex, fragrances, hair dyes, preservatives, medications, metals, or other similar substances.

The scratch test or intradermal tests provide immediate reactions. If a patient is allergic to the substances scratched or injected into the skin, he or she will develop red, itchy bumps. In contrast, patch tests result in delayed reactions. After application of the patches which contain allergens, the patches remain on the patient for about two days. The patient then returns to the doctor's office in order for the skin to be evaluated by the physician.