Doctors use several methods to perform allergy tests, but a common one is the skin prick test. This simple procedure helps identify substances that trigger allergic reactions.
The Skin Prick Test: A Step-by-Step Guide
The skin prick test involves the following steps:
- Preparation: Your doctor will clean the area of skin, usually the forearm, upper arm, or back, with an antiseptic solution.
- Allergen Application: Tiny drops of suspected allergens (the substances you might be allergic to, such as pollen, pet dander, or food extracts) are placed on the skin's surface.
- Pricking the Skin: A small lancet or other sterile needle is used to lightly prick the skin through each drop of allergen, allowing a small amount to enter just beneath the skin's surface. This doesn't cause significant pain.
- Observation: The doctor will observe the skin for reactions, typically over 15-20 minutes. A positive reaction (indicating an allergy) shows up as a raised, itchy wheal (or hive) at the prick site. The size of the wheal indicates the severity of the allergy. A negative reaction shows no noticeable change.
- Control Reactions: A control prick with saline solution (salt water) and sometimes a positive control (histamine) are performed. The saline control ensures that the skin reacts appropriately to the pricking itself. The histamine control is a known allergen that ensures the test is working correctly.
Other Allergy Testing Methods
While the skin prick test is common, other methods exist, including:
- Intradermal skin tests: These involve injecting a smaller amount of allergen under the skin using a very fine needle. These are often used when the skin prick test result is negative but allergy is still suspected.
- Blood tests (RAST): These tests measure the levels of specific IgE antibodies in your blood that react to certain allergens. Blood tests are useful if a skin prick test can't be performed (e.g., due to skin conditions or medications).
Example: Let's say someone suspects a cat allergy. The doctor would place a drop of cat allergen extract on their skin and prick it. If a wheal (raised, itchy area) appears, it suggests a cat allergy. The size of the wheal helps determine allergy severity.
Remember, allergy testing should always be performed and interpreted by a healthcare professional. Self-testing is not recommended. The information provided here is for general understanding and doesn't replace professional medical advice.
