Certain allergies are hard to detect. If your child has had symptoms similar to a cold for more than a week, allergies might be to blame. The first step is to make an appointment with your child's pediatrician who will refer you to a pediatric allergist at a clinic like Asthma and Allergy Clinic. Pediatric allergists are specially trained physicians who will run a gamut of tests to pin down exactly what your child is allergic to so he can recommend appropriate treatment.
There are several different kinds of skin tests that help detect the presence of an allergy. A scratch test is one type of test a pediatric allergist might use. Your child's skin, on the forearm or back, will be scratched with a tiny amount of a liquid extract of a certain allergen, such as a specific food.
If, after a period of time, a small red bump appears, called a wheal, an allergist will diagnose your child with that allergy. The size of the wheal indicates how sensitive a child is to that specific allergen, and the larger the wheal the more severe the allergy.
The allergist might conduct more than one type of allergen skin test at a time. Other skin tests involve injecting a small amount of the allergen under the skin to see if a reaction occurs.
Blood tests are necessary to affirmatively diagnose a food allergy, and they are accurate 90 percent of the time, according to the Asthma and Allergy Foundation of America. A small amount of blood is drawn out of your child's arm and sent to a laboratory for analysis. Those analyzing the blood are looking for the presence of antibodies, each of which indicates an allergy to a specific thing. The needle stick might hurt for a few seconds, but distracting your child with a book or favorite toy will help make the process less traumatic.
Eliminating suspected allergens from diet is another way to pinpoint exactly what your child is allergic to, though it's only useful in diagnosing food allergies. Your child's allergist will create a diet that eliminates one food for a period of four to seven days. If your child's symptoms continue, the allergist will recommend a different food to eliminate. Once symptoms disappear, the specific allergen is revealed. This test isn't as accurate as skin or blood tests, but it's often used if the allergist believes that your child is allergic to several foods.