Allergy Skin Tests

Allergy skin tests are a type of medical test used to diagnose allergies. The test involves placing a small amount of an allergen on the skin and observing the body's reaction.

Types of Allergy Skin Tests

• Prick test (or prick-prick test): This is the most common type of allergy skin test. A small amount of an allergen is placed on the skin, and the skin is then pricked with a small needle to allow the allergen to enter the skin.
• Intradermal test: This test involves injecting a small amount of an allergen into the skin using a needle. It is typically used for people who have a negative prick test but are still suspected of having an allergy.
• Patch test: This test involves placing a small amount of an allergen on the skin and covering it with a patch. The patch is left in place for 48-72 hours to observe any delayed reactions.

How Allergy Skin Tests are Performed

The procedure typically involves the following steps:

1. Cleaning the skin: The area of skin where the test will be performed is cleaned with an antiseptic solution.
2. Placing the allergen: A small amount of each allergen being tested is placed on the skin, usually in a specific pattern.
3. Pricking or injecting the skin: The skin is then pricked or injected with a small needle to allow the allergen to enter the skin.
4. Observing the reaction: The skin is observed for any signs of an allergic reaction, such as redness, swelling, or itching.

Interpreting Allergy Skin Test Results

The results of an allergy skin test are typically interpreted as follows:

• Positive result: A positive result is indicated by the presence of a wheal (a raised, itchy bump) and/or redness at the site where the allergen was placed. The size of the wheal can indicate the severity of the allergy.
• Negative result: A negative result is indicated by the absence of any reaction at the site where the allergen was placed.

Risks and Side Effects of Allergy Skin Tests

While generally safe, allergy skin tests can cause some side effects, including:

• Redness and itching at the test site
• Swelling or hives
• Anaphylaxis (a severe, life-threatening allergic reaction) - although this is rare

Preparation for Allergy Skin Tests

To prepare for an allergy skin test, patients should:

• Avoid taking antihistamines or other medications that may interfere with the test results for a specified period before the test
• Wear loose, comfortable clothing to allow easy access to the testing area
• Arrive at least 30 minutes before the scheduled test time to complete any necessary paperwork and preparation