Understanding Allergy Diagnosis

How are allergies diagnosed?

Many allergy symptoms are easily reconizable (e.g., sneezing, a runny nose, watery eyes) after exposure to certain triggers such as visiting the home of someone with pets or spending time outdoors during peak pollen seasons. However, allergies don’t always present themselves so clearly. Many chronic symptoms are easy to overlook or misattribute to other causes.

Self-diagnosis of allergy may lead to unnecessary avoidance of foods, medications, or certain environments. It may also lead to the overuse of symptomatic medications which have side effects like drowsiness, dry mouth, nose bleeds, or headaches. Allergy testing may allow you to better understand what is causing you respiratory symptoms and may help to identify possible food, drug, or insect venom allergies.

Step One: Physical Exam

Your doctor will begin by taking a complete clinical history, which involves asking a series of questions. Your answers to these questions will help your doctor gain insight as to the severity of your allergic symptoms.

Some examples of questions you may be asked are:

  • What type of symptoms do you have?
  • How long have you had these symptoms?
  • When do you experience these symptoms-seasonally or year-round? During the day or at night? Indoors or outdoors? At home or at work?
  • Is there any history of allergy in your family?
  • Do you have any other health conditions?

If the physical exam and clinical history indicate that you may suffer from allergies, your doctor will perform an allergy skin test to identify the specific cause of your allergies.

Step Two: Skin Prick Testing

Skin tests are performed in your doctor’s office and typically take one to two hours. A member of your doctor’s medical staff will press small amounts of allergen into the very top layer of skin with a plastic device. This takes seconds to apply and is typically done on the upper arm, the forearm, or the back. The number of tests may vary, but typically range from 40-60 different allergens. These allergens match common pollen, animal, and environmental exposures found in your region of the country.

In addition to testing to allergens, there will be two control tests-a positive control and a negative control. The positive control shows your allergic response is functioning properly, while the negative control ensures that reactions are truly due to allergy, and not skin sensitivity.

Once the tests are applied, the staff member will wait 15-20 minutes to give your skin time to demonstrate your reaction. Reactions look and feel very similar to a typical mosquito bite-a small raised circle surrounded by redness. This is referred to as “wheal and flare” and typically correlates with the severity of the allergy. In most cases, the bigger the circle, the more allergic.These wheals will typically go away within an hour, although some may linger for up to 24 hours. If you have any concerns after testing, contact your physician.

INTRADERMAL TESTING

Some allergy specialists may elect to perform a second round of testing called intradermal testing in order to get an even clearer picture of the severity of your allergy to any specific allergen. Intradermal testing involves injecting a small amount of allergen under the skin, usually on the upper arm, the forearm, or the back.

Step Three: Discuss Results & Options

Once your skin testing is completed, your doctor will walk you through the results and explain your options. You will then work with your doctor to develop a treatment plan that may include a combinations of avoidance, symptomatic medications, and allergen-specific immunotherapy.

When not adequately treated, allergic rhinitis has been associated with substantial impairments to overall quality of life caused by symptoms such as headaches, fatigue & decreased cognitive function.

Preparing for Allergy Skin Tests

There are a few things that may interfere with the success of your allergy test.

  • It is recommended that you avoid placing creams on the skin the day of testing unless directed by the health care provider.
  • All antihistamines should be stopped 2 to 7 days prior to testing. Your health care provider will provide withdrawal recommendations for specific medications.
  • Other medications, such as antidepressants, sleeping aids and herbal supplements may interfere with skin test results, so be sure to notify your health care provider of all medications you are taking.

Ask your doctor for a full list of medications to avoid when makeing your appointment. On the day of your appointment, if you are sick (i.e.,feverish) or if your allergy symptoms are particularly severe, contact your health care provider.

Who typically gets tested?

Children and adults can be tested for allergies. Check with your health care provider to see if there is any reason you should not be tested. One reason may be a severe skin condition that limits the areas where tests can be placed. A reason to delay testing is if a medication is being taken that may block or change the response to the tests.

Are the test safe?

Allergy skin testing is not unlike any other medical procedure, so there are always associated risks. The major concern is an allergic reaction and that is why this test is done in a health care provider’s office so you can be observed for any symptoms other than the expected local reaction. Studies show the chance of a severe allergic reaction is extremely rare.

Risk and warnings for immunotherapy

Although immunotherapy has been shown to be highly effective in treating the underlying cause of allergies, patients being treated may have side effects, You may experience one or more of these common reactions:

Local reactions

Although these local reactions may produce discomfort, they are not serious:

  • During immunotherapy, some individuals may experience pain, swelling and/or redness at the site of the injection.
  • Others may experience local swelling and soreness 8-12 hours after injection.
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