Overview of Allergy, Its Diagnosis and Treatment
Allergy is the inappropriate and harmful response of the body’s defense mechanism to substances that are normally harmless. It involves the immune system and particularly an antibody called immunoglobulin E (IgE).
The frequency with which allergy affects people varies greatly in different countries of the world, being as low as 1% or as high as 40%. The reasons for these wide geographic differences are not understood but are related, in part, to affluence and lifestyle.
In many countries of the world, doctors train specially in the treatment of allergic diseases and are known as "allergists." They can treat all types of allergic disease. The names of allergists in your country can be found by contacting your national professional allergy society. In other countries, family doctors, general physicians, oto-rhino-laryngologists (ear nose and throat specialists) or dermatologists (skin specialists) more commonly treat allergic diseases.
To diagnose allergy, your doctor will concentrate particularly on the symptoms that you describe but will also examine the affected part of your body and perform allergy tests. The most common of these tests is "skin prick/puncture testing." This test involves placing separate drops of solutions of allergen vaccines/extracts onto the skin of your forearm or back and then using a very fine needle to prick through the drop into the skin. A positive test results in a small raised wheal with a red surrounding flare. (Click here for a picture of the test and a positive result).
Similar results can be obtained by blood testing commonly known as RAST (radio-allergosorbent test). This test accurately measures the amount of the allergy antibody – IgE – in your blood that is directed against the allergens to which you are allergic. It is important to appreciate that the results of these tests must be interpreted in conjunction with your allergic history and that the results of the tests are not sufficient on their own to confirm the allergy diagnosis.
The diagnosis of food allergy requires additional tests such as food challenges and elimination/exclusion diets, which need careful advice and supervision from your doctor.
The diagnosis of contact dermatitis requires a "patch test." The cosmetic or substance you may be allergic to is placed on the skin and covered for 48 to 72 hours to determine whether it produces a rash. If so, you are allergic to it.