How do doctors test for allergies in teenagers?

Allergy Tests: Testing is usually performed by skin testing, which is still the gold standard for detection of allergies. Blood/serum rast testing is also becoming popular but these are not as sensitive as skin testing.

Same as any age: It is important to consider the allergic reaction that prompted the testing. We might have the allergy antibody in our blood but be meaningless, since the allergy reaction has many components. Conversely, what is tested may not be the same as the reaction. For example, apple and cooked apple or peeled apple might not have all the same allergic properties.