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What is a Skin Rash Test?

Although there are many reasons skin rashes may develop, they are often caused by immune reactions to allergens in the environment. Several different skin tests may be used to determine the source of the allergen.

  1. Scratch Test

    • According to Web MD, a scratch test is also known as a puncture or prick test. The doctor places a small amount of the allergen on the skin of the patient's forearm or back. He scratches through the drop with a special needle so the substance can enter the outer layer of the skin. Medicine Net explains that the test is positive if the spot turns red or swells.

    Patch Test

    • A patch test identifies allergens that affect the skin through direct contact. The doctor applies a specific allergen to a patch and places it on the skin, according to Web MD. The person's skin becomes irritated and itchy if he is allergic to the substance.

    Intradermal Testing

    • The health care provider uses a syringe to inject a small amount of allergen directly beneath the top layer of skin, where it forms a small bubble. If the skin becomes irritated, the test is positive. Lab Tests Online warns that this test is not frequently used because it gives unreliable results.

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