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Allergy Skin Prick Test

What is Allergy ?

Allergy is a clinical state where the body responds in an exaggerated manner to foreign stimuli called Allergen. Allergy is known to run in families and has a genetic predisposition. After the initial exposure to an allergen, a genetic predisposed individual produces specific molecules called Ig E antibodies. During the subsequent exposure to a similar allergen, the Ig E antibodies cross link causing release of bioactive amine called histamine which is stored in mast cells. It is the histamine that causes most of the early symptoms of allergy.

What are the common Environmental Allergens ?

Pollen grains, House Dust mites, mold, insects, animal dander and certain food products are the common allergens. The Allergens could be perennial like dust mites and insects or could be seasonal as in pollen grains. Pollen is released during the flowering season and this explains the seasonal exacerbation of symptoms in individuals allergic to certain pollen grains.

What are the symptoms of Allergy ?

Depending on the organ involved the symptoms could range from frequent colds, cough and wheezing, itchy red eyes and itchy skin rashes. In some individuals severe allergy reaction can cause life threatening event called anaphylaxis.

What is Allergy Skin Prick Test ?

This is a gold standard test to find out the causative agent for allergy. This is generally performed on individuals after 5 years of age with a strong suspicion of allergy. Once the severity of symptoms is brought down with medications, a skin prick test is scheduled. Care is taken to stop anti histamine medications a week prior to the test as these medications can interfere with the test results. Nasal sprays, drops and medicines like corticosteroids and monteleukast do not interfere with the test. However it is important that the individual being tested should furnish details of the all the current medications being taken including AYUSH related drugs.

The test is a painless and bloodless procedure done on the forearm or back. A set of allergens are selected for the test. These are selected based on the nature of symptoms (whether perennial or seasonal) and geographical location of the patient. The allergen extracts are then placed drop by drop over the skin and the area is gently pricked with a tiny lancet. A positive and negative control testing with histamine and saline respectively is also performed in order to ensure there is no false positive or negative results. The results are interpreted after about 20 minutes of the prick. A reddish itchy swelling over the skin indicates a positive reaction. The size of the redness and swelling is measured and documented. The test results are obtained in the same sitting. Some amount of local skin itching and redness maybe observed after the test which is self-limiting.

Is the test safe ?

The test is safe and doesn’t cause any major problem. Special Precaution is taken before the test to make sure that the individuals being tested do not have any acute or critical ongoing allergy symptoms like severe wheezing. The center performing the test is well equipped with emergency medications and trained doctors to handle any untoward medical emergency arising from the procedure.

Who cannot undergo the test ?

Very small children, pregnant ladies and individuals with recent anaphylaxis are not tested. Those with acute allergy symptoms are first treated with allergy medicines and after becoming stable are tested. People who are on antihistamines or any other traditional / Alternative therapy should withhold medications before the test.

Why is testing important ?

It helps us identify the causative factor for allergy. Appropriate avoidance measures can be followed by the individual to reduce the exposure to the identified allergen. Allergen immunotherapy / Vaccine in the form of sub cutaneous injections or sublingual drops and tablets for allergy can also be offered based on the skin prick test result in order to provide long term benefit and cure from allergy.

For more information on Allergy testing and immunotherapy, kindly get in touch with our specialist doctors at Bangalore ENT Institute.

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