MedifocusHealth

Allergy skin testing involves the introduction of allergen through a break in the skin. Allergy testing helps to determine exactly which substances are causing the allergic response so that an individualized treatment plan can be developed. The first skin test for allergies was performed by a physician names Charles H. Blackley in 1865.

The old approach of "scratch testing" has largely been abandoned due to discomfort, poor reproducibility and the possibility of scarring.

The current approaches to skin testing include:

• Skin Prick Testing - This test involves a series of injections in the skin of the back, each containing a small amount of a suspected allergen in a solution. Depending on the individual's history, the test may include as few as six allergens, or as many as eighty. If the patient is allergic to any of the allergens, a raised red spot like a hive, called a wheal and flare will appear at the site after about 20 minutes. Although very rare, systemic reactions (and even fatalities) to skin testing have been reported.

• Intradermal Skin Testing - This test, which is performed by injecting a drop of an allergen extract into the skin, has a very high non-specific reaction rate, but is useful for investigating drug and stinging insect allergy.

• Blood Specific IgE Testing (e.g., ImmunoCAP) - This test measures the amount of IgE in the blood and can identify and quantify the person's specific allergic sensitivities. This approach can be performed in a primary care setting, carries no risk of anaphylaxis, and does not require the discontinuation of any medications (that might interfere with the test results) prior to testing.