Diagnosis of Indoor Allergies

Knowing what particular allergen is causing allergy symptoms can help determine what steps are needed to reduce exposure to that allergen. Reducing exposure to an allergen can require simple or more involved changes in daily life.

Allergy testing is the only way to diagnose an indoor allergy with certainty. Allergy diagnosis first involves taking a patient history that includes detailed information about allergy symptoms and when they occur. Based on this information, testing for one or more allergens is performed.

Allergy tests can be done several different ways. A skin test involves exposing small patches of skin to different allergens. If a small hive or wheal (raised, itchy, red patch of skin) appears at the site where the specific allergen was applied, an allergy to that substance is indicated. Skin tests can involve a puncture, prick, or scratch of the skin where the allergen is applied. These tests cause little, if any, discomfort and the results can be obtained in about 15 minutes.

Another type of allergy test involves checking a blood sample for the presence of certain antibodies. There are many different allergy blood tests, including the radioallergosorbent test (RAST) and the enzyme-linked immunosorbent assay (ELISA). Results of these tests take longer than a skin test because the blood sample often must be sent to a laboratory for examination.

The type of allergy testing that is performed depends on a number of factors, including the patient's medical history. For example, people who have eczema (dermatitis) should not undergo skin testing. Antihistamine medication can interfere with the accuracy of allergy testing and should be discontinued at least 24 hours before any test is done.

For more information about allergy tests, please go to Allergy Testing.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 22 Oct 2008

Last Modified: 22 Sep 2015