Types of Allergy Tests
- Allergy Skin Testing. …
- Blood tests. …
- Spirometry (Lung Function Tests) …
- Food Challenges. …
- Drug/medication Challenge. …
- Aspirin Desensitization. …
- Patch Testing.
Allergy occurs when a person reacts to substances in the environment that are harmless to most people. These substances are known as allergens and are found in dust mites, pets, pollen, insects, ticks, moulds, foods and some medications.
Atopy is the genetic tendency to develop allergic diseases. When atopic people are exposed to allergens they can develop an immune reaction that leads to allergic inflammation. This can cause symptoms in the:
- Nose and/or eyes, resulting in allergic rhinitis (hay fever) and/or conjunctivitis.
- Skin resulting in eczema, or hives (urticaria).
- Lungs resulting in asthma.
Prick and Intradermal Allergy Skin Tests
Prick and intradermal skin tests are the norm for suspected seasonal, environmental, stinging insects, food, and medication allergies. During the test, the suspected allergen is positioned on the skin and evaluated after 15 minutes for signs of allergic reactions. While prick testing uses a pricking device to place the allergen on the skin, intradermal skin testing involves placing a solution containing the allergen just below the skin via a small needle.
Blood Tests for Allergies
Skin testing is more common, but blood testing for allergies is also available. Typically, blood tests are recommended when patients cannot stop using antihistamines and other medications long enough for skin testing, when patients have dermatographism (hives resulting from scratching the skin), or when patients’ skin has lesions or rashes that might interfere with skin testing. These blood tests, known as specific IgE tests or RAST tests, help evaluate a patient’s suspected allergies, much like skin tests but using a blood sample.
Food and Drug Challenge Tests
Confirming a food or drug allergy may require food or drug challenge testing. The patient is given an incremental dose of food or drugs suspected of causing allergic symptoms, and then the patient is observed between doses to assess allergic reactions. Because of the risk of allergic reactions, food and drug challenge tests are supervised by a physician.
Patch Allergy Testing
Patients with contact dermatitis may benefit from patch allergy testing. This testing can help to reveal an underlying trigger for the condition, which often produces symptoms after using skincare products or wearing metal jewelry. The test requires wearing a patch with the suspected agent on the back for 48 hours, after which time the skin is evaluated for signs of contact dermatitis.