What are skin allergy tests?
Skin allergy tests help to identify the substances that cause allergic reactions to the sufferer. A very small amount of the allergen is made to penetrate the skin through different methods. If the person is sensitive to that particular substance, there will be a distinct bump or weal at that place. This is a reliable test that can provide valuable insight in the management of allergies.
Why is it conducted?
For people whose quality of life is affected by frequent allergies, this can be a godsend as it helps to:
- Avoid these triggers by keeping their immediate environment free of them.
- Take preventive medicines, for instance, taking antihistamines when they are bound to be exposed to the allergen.
- Get immunity shots that gradually develop tolerance against the allergen.
Who should go for it?
Unless you are acutely sensitive, allergies are not life threatening. However, if you are facing recurrent allergies, they can severely disrupt normal activities.
- People who have allergic rhinitis, hay fever or poorly controlled allergic asthma are generally advised to have this test.
- Persons who have skin rashes as a response to certain allergens.
- Persons suffering from angioedema, which is swelling beneath the skin instead of on the surface.
- People who are prone to food allergies.
Allergy skin tests may be performed on the forearm or the back of the patient. There are two ways of conducting skin allergy tests.
- Prick test: In this a number of allergens are either scratched on the skin or pricked to see their effect on the person. Several allergens can be tested at the same time at different points in the skin. Noticeable bumps will rise when the person is allergic to a particular substance. The results of this test can be had within half an hour. In some cases, the allergen is injected just beneath the surface of the skin.
- Patch test: In this the allergens are applied on the skin with the help of a patch that you have to wear for 48 hours. This test is generally used for skin allergies or dermatitis. In this test you get the results after a couple of days.
Interpretation of results
The interpretation of skin allergy tests involves considerable skill of the tester. Normally histamine and saline solution is also applied to check for general sensitivity. If you do not react to histamine, then your skin allergy test cannot be considered reliable. However, if you react to saline solution, then you have an overly sensitive skin, which again affects the accuracy of the test. In addition to this, if you are taking antihistamines for your allergies, then this is likely to affect the result of the test. People with widespread skin problems like eczema or dermatitis cannot have this test and may be advised a blood test instead.
The allergens are applied in a certain order on marked points and this helps to pinpoint the substances that caused the reaction. The bigger the bump, the more sensitive you are to that particular substance.