Could you tell me what happens when you go to an allergist?

Usually skin tests: It depends why you are going of course, but typically we will do testing to see what you are allergic to. The nature of that will vary depending on if you're allergic to medications, insects, pollen, etc. Scratch tests are most common, and involve a small amount of liquid extract on an applicator which then scratches the skin. Does not draw blood, and can itch but not really hurt.