- Allergists may use a skin prick test - Stock xchng photos
According to the American Academy of Allergy, Asthma & Immunology, there are more than 50 million people in the United States with allergies. Since reactions to allergens can range from simply annoying to life threatening, it is very important that those who suspect they have allergies seek treatment. The first step to effective treatment is a clear diagnosis of what triggers one's immune system to respond in this way.
Under the guidance of an allergy specialist, or allergist, either a skin or blood test can be administered to determine what causes allergic reactions. An allergy test can help identify an allergy to pollen, mold, dust mites, animal dander, insect stings, foods, certain medicines, and other substances as well.
Skin Tests for Allergies
During a skin test, a small amount of allergen is placed in contact with the skin to determine the level (if any) of allergic reaction. A skin test may take one of three forms:
- skin prick test: In this test, a drop of allergen-containing solution is placed on the skin, then a series of scratches or needle pricks is done to let this solution enter the skin. A positive result is indicated by a red, raised itchy bump (called a wheal) and means an allergy exists. A skin prick test is usually conducted on the back or forearm.
- intradermal test: This test is conducted by injecting a small amount of allergen solution into the skin. It is a much more sensitive test. An intradermal test is usually performed on the arm.
- skin patch test: For this test, a pad containing some of the allergen solution is tapes to the skin and left for 24 to 72 hours. This kind of test is used to diangose contact dermatitis, an intense reaction of the skin to an allergen.
Reactions to a skin test typically appear within 20 minutes, so a diagnosis is fast. Redness and swelling may result at the test site, but usually go away within a few hours. These tests are not very painful and most adult patients can tolerate them well.
Blood Tests for Allergies
When a skin test is not an option, an allergist will perform a blood test. These tests are less sensitive, but can determine allergies to many substances at once. A blood test measures the antibodies present when the person is exposed to specific allergens. This testing must be conducted at a lab, so results can take days to come back.
Blood tests are usually performed, according to WebMD, if a person has hives or another allergic skin condition, such as eczema. It may also be used when a patient cannot discontinue use of a medication that would interfere with the results of a skin test. Also, a severe reaction, such as anaphylaxis, may make a skin test unsafe, so a blood test is usually performed. Babies and small children typically receive blood tests for allergies, since the discomfort of one needle prick to draw blood is less stressful than a full skin test.
Many different common allergens can be tested by both skin or blood tests on adults and children. Once a diagnosis is in hand, an allergist can make clear suggestions for treatment, lifestyle changes, and symptom management. Most people who have allergies don't realize how much better they can feel with proper treatment, according to the American Academy of Allergy, Asthma, & Immunology.
References:
- American Academy of Allergy, Asthma & Immunology. "Tips to Remember: Allergy Testing."
- American College of Allergy, Asthma & Immunology. "Allergy Testing."
- Web MD Allergies Health Center. "Allergy Tests."
Stephanie Haddad - Stephanie Haddad is a freelance writer living in the Boston area with her husband, their dog, and their new daughter. She focuses her work ...
