The primary method to test for egg allergy on the skin is a skin prick test, a safe and low-risk procedure.
Here's a breakdown of how the skin prick test is performed to detect egg allergy:
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Preparation: A clinician will clean and mark a small area of skin, usually on the forearm or back.
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Application of Allergen: A drop of liquid containing egg protein (the suspected allergen) is placed on the marked skin.
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Skin Prick: The skin is then lightly pricked through the drop with a sterile lancet or needle. This allows a tiny amount of the allergen to enter the skin.
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Observation: The clinician will observe the site for a reaction over approximately 15-20 minutes.
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Reading the Results: A positive reaction typically involves the development of a small, raised, itchy bump (wheal) surrounded by redness (flare). The size of the wheal is measured and compared to a control solution (histamine). A larger wheal suggests a higher likelihood of allergy.
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Interpretation: The results are interpreted by the clinician, taking into account the patient's history and other relevant information. Mild itchiness, bumps, or hives are the most common reactions.
Important Considerations:
- Skin prick tests should always be performed under the supervision of a qualified healthcare professional who can manage any potential allergic reactions.
- Antihistamines should be avoided for several days before the test, as they can interfere with the results.
- A positive skin prick test doesn't always mean someone is allergic to egg; it indicates sensitization. Clinical history and other tests might be needed for a definitive diagnosis.
- A negative skin prick test is more reliable in ruling out an egg allergy.
