Why are allergy tests done?

When you have nasal symptoms that last longer than 2 weeks and keep coming back, you should consider making an appointment with your doctor for a complete medical evaluation.

Before your appointment, you should keep a diary of your symptoms. In many cases, your condition can be diagnosed by your medical history and a physical examination alone.

The season in which your symptoms occur will narrow the list of possible causes. Your doctor may wish to perform skin testing to determine which allergens (substances that bring about allergies) are causing your symptoms. A blood test for allergy can be obtained as an alternative, but this is not as sensitive as skin testing.

Because hay fever often is associated with asthma, tests to rule out this condition may be done, as well. Asthma refers specifically to a reaction in the airways that frequently (but not always) involves an allergy. The majority of adults with asthma, and an even larger majority of children with asthma, have an allergy to one or more substances.

What are allergy skin tests?

An allergy skin test is used to identify the substances that are causing your allergy symptoms. It involves applying an extract of an allergen to your skin, scratching or pricking the skin to allow exposure to the allergy, and then evaluating the skin's reaction.

What to expect: First, a doctor or nurse will examine the skin on your forearm and clean it with alcohol. (Sometimes, this test is performed on the back.) Areas on your skin are then marked with a pen to identify each of the allergens that will be tested. A drop of an abstract made from each allergen — such as pollen, animal dander, or mold spore — is placed on the mark on your skin.

A small disposable pricking device is then used to make sure the extract enters the outer layer of the skin (the epidermis). The skin prick is not a shot and does not cause bleeding. Sometimes an additional test is performed where a small amount of allergen is injected just under the skin to determine a complete list of possible allergies.

The areas of the skin that become red and itchy indicate the substances that cause a defensive response by your immune system. The skin reaction may be itchy.After the test, the extracts and ink marks will be cleaned off your skin with alcohol. A mild cortisone cream will be applied to your arm (or back) to relieve any itching at the sites of the skin pricks. Your doctor or allergist will use the results of the test to help develop a management plan for you.

To prepare for the test: Antihistamines stop allergic reactions and should not be taken for 5 days before the test.

Your doctor will give you a list of medications to avoid before the test, since there are other medications (such as tricyclic antidepressants) that may interfere with the test. Give the healthcare provider who is going to perform the skin test a list of all the medications you are taking, including over-the-counter ones. Talk to your doctor about stopping your prescription medications before the test.

What questions will your doctor ask when taking a medical history for allergies?

  • What type of symptoms do you have?
  • How long have you had these symptoms?
  • When symptoms occur, how long do they last?
  • Are your symptoms seasonal (come and go throughout the year) or do they last year-round?
  • Do your symptoms occur when you are outdoors or indoors?
  • Do your symptoms get worse when you are around pets? Do you have any pets?
  • Do you smoke? Does anyone in your family smoke?
  • Are your symptoms interfering with your daily activities or interrupting your sleep?
  • What makes your symptoms better? What types of treatments have you tried?
  • What medication(s) are you taking now for symptom relief? Do these medications provide relief? Do they cause drowsiness?
  • What medication(s) have you tried in the past? Were these medications helpful?
  • What other medications are you taking, including prescription, over-the-counter, vitamins, and herbal supplements?
  • What type of heating system do you have? Do you have central air conditioning?
  • Do you have any other health conditions, such as asthma or high blood pressure?
  • Are you having difficulty with your sense of smell or taste?
  • What makes your symptoms worse? Better?
  • How much can you modify your lifestyle to reduce your exposure to these allergens?

What questions should you ask your doctor about allergies?

  • What substances are causing my allergies?
  • What allergy symptoms should I be concerned about? When is it necessary to call the doctor?
  • What allergy medications or other treatments are available? What are the benefits and side effects of each treatment?
  • Am I a candidate for allergen immunotherapy (allergy shots)?
  • What guidelines should I follow if I'm prescribed allergy medication?
  • Should I take medicine all the time or only when my allergy symptoms get worse?
  • Should I stop exercising outside if I have allergies?
  • How can I avoid or reduce exposure to certain allergens?
  • What can I do around my house to reduce exposure to allergens?
  • Should I avoid going outside during certain times of the day?
  • What can I do to lessen allergy symptoms when I do have to go outside?
  • How often should I come in for follow-up appointments?

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