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Allergy Tests: What to Expect

Whether your allergies are seasonal or year-round, antihistamines and decongestants can only go so far. If you’re ready to seek long-term treatment for your allergy problems, below are some details on what to expect.

Initial Diagnosis

In many cases, an allergy sufferer visits his or her physician, explains symptoms, and is given a mild daily allergy prescription, such as Claritin or Semprex. This is for mild, seasonal cases and is intended as a short-term solution.

If your allergies are more severe or year-round, your physician may recommend allergy testing. You may choose to do this testing anyway, as it gives a complete picture of your specific allergens. While you’ve likely heard stories about thousands of needle pricks, allergy testing is not anything to be afraid of. There are several types of allergy tests and each test is done under close supervision.

Skin Tests

To determine the substances causing your symptoms, your doctor will likely first try the skin scratch test. A small amount of each possible allergen is placed on the patient’s skin, lightly scratching the skin with the needle to allow the allergen to go further into the skin. The doctor then waits to see if the skin swells or reddens. Since results are seen within 15-20 minutes, the patient is closely monitored during this time. However, it should be noted that occasionally the patient sees results hours after testing occurs.

If a scratch test is unsuccessful in determining a patient’s allergens or if a specific allergen needs to be tested, physicians may order an intradermal skin test, where the allergen is injected into the skin. Like the scratch test, the doctor then waits to see if there is a reaction.

A third type of skin test is called a patch test. Allergens are attached to the skin and left for up to 48 hours. This method is used when a doctor needs to test skin reactions to certain items and the doctor will usually check the skin after 24 hours, then again after 48 hours.

Naturally, the biggest danger in all of these tests is that a patient will react to a large number of allergens at once. Itching, dizziness, and occasional fainting have been reported as a result of these tests.

Process of Elimination

Elimination tests are used primarily with food allergies. The physician has a patient remove certain items from his or her diet to determine if symptoms abate. Once the item has been absent from the patient’s diet for a period of time, the physician will then have the patient gradually add the item back into his or her diet and see if symptoms return.

Elimination tests can be especially difficult in children whose parents aren’t always in control of what they eat. One simple slip-up can negate all test results, so parents need to understand the importance of making sure the child sticks to the diet at all times, even while at school or out with friends.

Blood Tests

If skin testing is not an option, a physician may prescribe a blood test to determine the presence of antibodies to certain allergens in the blood. Since this test requires only one needle, some patients prefer this method. This test, called ImmunoCAP, compares well against traditional skin tests in studies.

However, in a University of Chicago study, a few allergens were not detected as well. Those included Aspergillus fumigatus, English plantain, oak tree, lamb’s quarter, and white ash tree. The study was successful in detecting many major allergies, however, including giant ragweed and Timothy-grass.


In some instances, a patient is tested by directly exposing them to the allergen. This may be done through having the patient inhale or ingest the substance in a controlled environment, under direct supervision by a physician.

In some cases, the patient may engage in a double-blind test, where the allergen is disguised within other substances. The patient then tries a placebo and the allergen to determine if the allergic reaction is mental or physical. While this can be effective, it will require multiple visits if the patient is allergic to more than one substance. It can also be more dangerous and should only be done under medical supervision.

Once you’ve completed allergy testing, you will receive a detailed analysis of your allergens. This can help a physician develop a course of treatment that may involve creating an inoculation to help you begin the path to eliminating your allergy, as well as avoiding the substance in your day-to-day life.

Content licensed from:

Written by: Stephanie Faris
Medically reviewed : George Krucik, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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