Finally, if this careful observation of the child does not seem to give an answer of what the allergen is, skin testing may be performed. Skin testing is done by the physician by dipping a sharp sterile metal tester into a solution made up of the components that are thought to be the allergens. The skin is then pricked. This deposits a small amount of the allergen under the skin. If the person is sensitive to the allergen a large red spot that may itch will appear at the prick spot within about 15 minutes. Each allergen must be tested with a separate prick, and there are literally hundreds of these solutions from which to choose. Obviously, you can't test for every one or the child would have to endure a lot of pricks. Therefore, coming to the doctor armed with your careful observations will help narrow down what to test for.
So, once the allergens are identified, how do you have your child avoid them?
Some things are obvious. If his symptoms get worse when he's around the neighbor's cat, then he shouldn't play with the cat. However, many allergens are not that easy to avoid.
Indoor allergens are a little easier to deal with. Dust mites, cockroaches, molds, and pet dander are some of the more common sources of indoor allergens. And even though you may feel you keep your house immaculately clean, these microscopic particles may be found in almost anyone's house. While there are elaborate, very time-consuming strategies that may be employed to limit allergens in the household, most parents find that following all the possible ones is tiring and discouraging. Therefore, here are some reasonable interventions that may be tried that hopefully will not be overwhelming or prohibitively expensive: