Diagnosis

Your doctor may suspect dust mite allergy based on symptoms and your answers to questions about your home.

To confirm that you're allergic to some airborne substance, your doctor may use a lighted instrument to look at the condition of the lining of your nose. If you have an allergy to something airborne, the lining of the nasal passage will be swollen and may appear pale or bluish.

Your doctor may suspect a dust mite allergy if your symptoms are worse when you go to bed or while cleaning — when dust mite allergens would be temporarily airborne. If you have a pet, it may be more difficult to determine the cause of the allergy, particularly if your pet sleeps in your bedroom.

• Allergy skin test. Your doctor may suggest an allergy skin test to determine what you're allergic to. You may be referred to an allergy specialist (allergist) for this test.

  In this test, tiny amounts of purified allergen extracts — including an extract for dust mites — are pricked onto your skin's surface. This is usually carried out on the forearm, but it may be done on the upper back.

  Your doctor or nurse observes your skin for signs of allergic reactions after 15 minutes. If you're allergic to dust mites, you'll develop a red, itchy bump where the dust mite extract was pricked onto your skin. The most common side effects of these skin tests are itching and redness. These side effects usually go away within 30 minutes.

• Allergy blood test. Some people can't undergo a skin test because they have a skin condition or they take a medication that can affect the results. As an alternative, your doctor may order a blood test that screens for specific allergy-causing antibodies to various common allergens, including dust mites. This test may also indicate how sensitive you are to an allergen.