Testing for allergies is conducted by a qualified allergy specialist to assess whether the body has allergic reactions to a known substance. The allergies testing can be performed on blood, skin, or on a specific diet. If you have an allergy, the immune system, which is your body’s natural defense system, overreacts to something in your environment that you have inhaled, touched, or ingested. Your immune system regulates the way the body protects itself.
For example, if you have an allergy to pollen, your immune system will perceive pollen as an invader or allergen. Your immune system over-reacts by creating antibodies called Immunoglobulin E (IgE). These antibodies travel to cells that release chemicals and cause allergic reactions. These reactions can range from irritating sneezing and sniffing to life-threatening reactions called anaphylaxis.
Types of allergy tests
The easiest and safest way to tell what triggers your symptoms is a test. Popular triggers include dust mites, animal dander, molds, pollen, cockroach droppings, stinging insects, food, latex and drugs.
Skin tests: This is the most prevalent method of testing for skin allergies. The allergist will put a small amount of allergen on your skin in this test, and the region is pricked or scratched. You will feel a little swelling at the site of the prick test if you are allergic. Usually, results are available within 15-20 minutes.
Intradermal tests: Intradermal testing is more reliable than prick testing and used if the results of the prick test are inconclusive. Your allergist will use a syringe in this test to inject some allergen into your skin.
Blood Tests: The doctor will take your blood sample and screen it. It costs more than other tests. It would also take longer for your results to be received from the laboratory.
Challenge tests: Often challenge tests are used when a doctor suggests that you are allergic to particular food or medications. In this test, under the close supervision of an allergist, patients eat or inhale a tiny amount of potential allergens. Do not try this test at home!
Patch tests: Patch testing for allergies is conducted to see if a substance causes allergic skin inflammation (contact dermatitis). Delayed allergic reactions can be identified by patch tests, which can take many days to develop. Patch tests use no needles. The allergist will apply allergens to the patches then placed on your skin.
To conduct and interpret allergy testing, an allergist should have advanced training. Your allergist will work with you to create a treatment plan for your allergies after you get your testing results.
You will know the results of a skin prick test or an intradermal test before you leave your doctor’s office. However, a patch test can take several days or more to get the results. A positive skin test shows you are allergic to a specific substance. Typically, larger wheals show a greater sensitivity. A negative skin test shows you are not allergic to a specific allergen.
Remember, skin tests aren’t always accurate. They often suggest an allergy when there is not one (false-positive), or if you are exposed to something you are allergic to, skin testing does not cause a reaction (false negative). On various occasions, you can respond differently to the same test carried out. Therefore, during a test, you can respond positively to a substance but not react to it in everyday life.
Medications, immunotherapy, modifications to the work or home environment, or dietary changes may be part of your allergy care plan. Ask your doctor to explain something you don’t understand about your condition or treatment. You’ll be able to minimize or eliminate allergy signs and symptoms with test results that identify your allergens and a treatment plan to help you take control.
Risks of allergy testing
Allergy tests can cause minor itching, redness and swelling of the skin. Often tiny bumps called wheals appear on the skin. These symptoms sometimes become apparent within hours, but can last for a few days. Mild topical steroid creams can relieve these symptoms. In rare cases, tests cause an acute allergic reaction that needs medical attention.
That is why allergy testing is crucial at a doctor’s office that has appropriate drugs and supplies, including epinephrine, to treat anaphylaxis, which is a potentially life-threatening acute allergic reaction. Call your doctor immediately if you have a severe reaction right after you leave the doctor’s office.
After Testing for Allergies
Call the emergency services immediately if you have signs of anaphylaxis, such as swelling of the throat, trouble breathing, rapid heart rate, or low blood pressure. Severe anaphylaxis is an emergency medical condition. When your doctor has decided which allergens are causing your symptoms, you will work together to create a strategy to stop them. Your doctor may also prescribe drugs that may ease your symptoms.
Frequently Asked Questions
Skin tests produce fast results. They typically cost less than blood testing for allergies. Blood tests are useful since they require a single needle prick. However, it takes a long time to get the results and, depending on the test, there could be false positives.
There is little or no pain from both types of skin tests. Positive responses, however, cause irritating itchy red bumps that look like mosquito bites. In only a few quick minutes or hours, the scratching and bumps are gone. To help decrease the reaction, your allergist can apply a cream to your skin or make you take an antihistamine afterward.
Some drugs interfere with skin tests. An allergist will inform you whether you need to change your medication before testing your skin for allergies.
An allergy blood test will help find pollen allergies, molds, dust mites, animal dander, insect stings, foods, and certain medicines.
Skin testing is the standard process, but your doctor can order blood tests in some situations. Allergy blood tests are important if you are using a drug that is messing with the test results and cannot avoid taking it for a few days. This may include antihistamines, some antidepressants, and steroids. Your doctor may also recommend blood test if you have allergic asthma, severe eczema, dermatitis, psoriasis, or having an extreme reaction during skin tests or a history of life-threatening allergic reactions called anaphylaxis.
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- ALLERGY TESTING. American Academy of Allergy, Asthma & Immunology.
- Blood Testing for Allergies. webMD.
- Allergy skin tests. By Mayo Clinic staff.
- Allergy Testing. American College of Allergy, Asthma & Immunology.
- How Do Doctors Test for Allergies? KidsHealth.