Diagnosing Allergies

Allergic individuals might have any number of physical signs of allergy. A well-trained and credentialed allergy doctor will look for a few high points that include: 
The eyes might be mildly to strikingly bloodshot. They might also be watery. There might be swelling of the eyelids. The area beneath the eyes might be puffy and dark. 
Structures inside the nose might be enlarged. The nasal lining might be swollen and discolored. Copious amounts of mucus might be present. There may be pus in the nose if the sinuses are infected. Fresh or dried blood might be present. And nasal polyps are a possibility. 
Prolonged nasal congestion can contribute to buckteeth. Similarly, the hard palate might be highly arched. Post-nasal drainage is indicative of sinusitis. 
Poor air movement and wheezing might be heard when listening to the lungs of an asthmatic. And asthma can lead to an increased front-to-back diameter of the chest. 
The skin might show rashes of allergic eczema, hives or related conditions. It might also reveal marks from vigorous scratching of itchy skin. 
Common laboratory tests in allergy diagnosis include microscopic examination of nasal mucus, pulmonary function studies, and blood tests to determine, among other things, amounts of allergic antibodies and other gamma globulins and “allergy cells.” 
Chest x-rays are sometimes indicated. More often, computerized tomography (CT scan) of the sinuses is of value. 
And of course, allergy skin testing is probably the single most important special study done by allergists. 
Allergy Skin Testing
Allergy skin testing is a diagnostic tool that can be done to find out for sure if you have allergies, and, if you do, to discover what you are allergic to. Although it is also possible to do blood tests for allergies, the most reliable testing for allergies is done by introducing extracts of tiny amounts of substances to which you might be allergic into the surface of your skin. 
If your immune system has produced allergic antibodies, some of them will be attached to so-called “mast cells” in your skin. And even if your allergies don't cause rashes or hives, localized reactions similar to mosquito bites will appear where your skin is pricked with extracts of substances to which you are allergic. 
A number of extracts are usually used and those to which you react are your particular allergens. Extracts of substances to which you are not allergic won't cause a significant reaction on your skin.