A doctor will use two primary tools to arrive at a diagnosis of allergies: the patient’s history and a physical examination. In the vast majority of cases, the history alone will suggest the diagnosis. Results of the physical exam are also helpful, while laboratory testing is needed to clarify the diagnosis of an allergy only in a small percentage of cases.
Several tests might be necessary to determine the allergens to which a child is reacting. Since the history is so important, prior to a medical evaluation it would be helpful to think back over the past few months (or years) to recall specific details of your child’s symptoms: When did the problem first start? How often does it bother her? What time of the day (or year) is it worse? Are symptoms more severe at home, outside, inside, in the city, out in the country, at the coast, or at high altitudes? Do the symptoms change with physical events or environmental factors such as cold, heat, dampness, exercise, or exposure to cigarette smoke? Have specific medications been used? Which of these has been most effective? Sometimes a diary can help you recall specific reactions, symptoms, and seasonal responses your child has experienced. Details about your child’s environment, especially her bedroom, could be helpful. Stuffed toys, pillows, the furnace and its filter, knickknacks and blinds (which collect dust), and trees outside the window are all potential sources of allergens.
During the physical exam, the doctor will look for various signs of allergic activity. These might include pale, swollen mucous membranes, clear drainage from the nose, an allergic “crease” across the nose, or perhaps dark “allergic shiners” below the eyes. Wheezing or coughing would of course be significant but may not necessarily occur during a scheduled office visit. The skin will be checked for evidence of eczema, including scratch marks and areas of thickening and redness, especially behind the knees, in the creases of the arms, and on the wrists.