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Getting an allergy test? Here's what to expect

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As the sixth leading cause of chronic illness in the United States, allergies affect about 50 million Americans each year. If you are trying to determine what you're allergic to, or if you're bothered by allergy signs and symptoms, your provider may recommend an allergy test. 

What is an allergy test and what should you expect during your visit? Keep reading to learn more. 

The importance of allergy tests

An allergy develops when the immune system identifies a substance as harmful and launches an excessive attack against it. Some of the most common substances that people develop allergies to include pet dander, pollen, dust, mold, latex and certain foods or medications. 

When exposed to a triggering substance (allergen), the immune system creates proteins called immunoglobulin E (IgE). These proteins stimulate the release of other chemicals that can lead to classic allergy symptoms, including:

  • Watery and itchy eyes
  • Sneezing and nasal congestion
  • Sore throat
  • Cough
  • Hives, swelling or itching on the skin
  • Swelling of the lips or tongue
  • Nausea, vomiting or diarrhea


Allergy symptoms vary in type and severity. (In extreme cases, called anaphylaxis, allergic reactions can be life-threatening and cause issues like facial swelling, breathing problems, decreased blood pressure and shock.) But whether an allergic reaction is mild or severe, knowing the cause of a person's allergy can dramatically improve that individual's health, safety and quality of life—which explain why allergy tests are so valuable! 

An allergy test measures the body's response to allergens.  These tests help doctors and patients learn which substances should be avoided to help control symptoms. Allergy tests also help guide treatment decisions, such as what type of medication a person should take or carry with them for emergencies. Sometimes, health care providers recommend allergy tests for people with asthma, as these tests may identify substances that can trigger or worsen an asthma attack.

What to expect during an allergy test

There are several types of allergy tests, including skin prick (scratch) tests, blood tests and challenge tests. Your health care provider, such as an allergist or dermatologist, will help you determine which test or tests are most appropriate for you.

Skin prick tests are the most common type of allergy test. Here's what to expect: 

  • Within a week of your appointment, your doctor may ask you to stop taking any allergy medications, as they may interfere with the accuracy of the testing.
  • During the appointment, your doctor will expose and cleanse an area of your skin, such as your back or forearm. Then they'll either use a thin needle to prick your skin with samples of potential allergens, or they'll place droplets of potential allergens on your skin and use a tool to gently "scratch" the area so the droplets get into the skin. Anywhere from 10 to 50 potential allergens can be tested in one allergy test.
  • You and your doctor will then watch to see whether any of the droplets trigger an allergic reaction in your skin, which may present as a red itchy rash or round spots called wheals. These reactions usually develop within 15 minutes and go away after about two to three hours.
  • Depending on the results of your test, your doctor will be able to make further recommendations for treatment or testing. 


Skin prick tests are not appropriate for everybody. The specific type of allergy test or tests you'll need depends on factors unique to you, including your signs and symptoms and your family and personal health history.

Do you have questions about allergies or allergy testing? 

If you're interested in allergy testing or would like to learn more about your treatment options, find a doctor today. SIU Medicine is central and southern Illinois's premier resource for personalized medicine and wellness services. It’s home to more than 300 compassionate and experienced health care providers, as well as a diverse team of caregivers, researchers, educators and clinicians-in-training.

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