Allergy Testing

What is an allergy test?

Healthcare providers perform allergy tests to determine what substances (allergens) are causing you to have allergy symptoms. Your provider will test how your body reacts to common allergens in a controlled setting during this test.

People can be allergic to things in the environment like mold, pollen and pet dander. Some people have allergic reactions to bee stings or latex. People with food allergies may not be able to eat peanuts, milk or soy without having a reaction.

An allergy test allows your healthcare provider to pinpoint what’s causing the reaction and work on a treatment plan to help manage your allergy symptoms. Allergy tests are safe and effective in diagnosing allergens.

What are the types of allergy tests?

There are different ways to test for allergies. Your allergist will select the best method based on your symptoms, age and what they suspect is causing the allergic reaction.

These tests include:

• Skin prick (scratch) test: Your provider uses a thin needle to prick the skin on your forearm or back with potential allergens. Or your provider may place droplets of potential allergens onto your skin and use a device to scratch and lightly puncture the area, causing the liquid to enter your skin. Reactions such as redness typically occur within 15 minutes of exposure. Your reaction might be a rash or raised, round spots called wheals. This test checks for airborne allergies, food allergies and penicillin allergies. Skin prick tests are the most common allergy test.
• Intradermal skin test: You may get an intradermal skin test if skin prick test results are negative or inconclusive. Your provider injects small amounts of an allergen into the outer layer of your skin (epidermis). This test checks for allergies to irritants in the air, medications and insect stings.
• Patch test: This test determines the cause of contact dermatitis. Your provider places drops of an allergen onto your skin and covers the area with a bandage. Or your provider may apply a patch (bandage) that has the allergen on it. You leave the bandage on and return to the provider’s office within 48 to 96 hours. Then, your provider removes the bandage to check your skin for a rash or other reaction.
• Blood (IgE) test: Your provider sends a sample of your blood to a lab. The lab adds allergens to the blood sample and measures the levels of immunoglobulin E (IgE), an antibody involved in allergies. IgE antibodies in it. A total IgE test measures the total amount of IgE antibodies. A specific IgE test measures how much IgE your body makes in response to a single allergen.
• Oral challenge test: This test occurs only under a provider’s supervision in their office. People with a food or drug allergy swallow (or eat) a small amount of a suspected allergen. An allergist typically performs this test. Medical supervision is a must in order to treat any symptoms that may develop during the challenge.

Why do healthcare providers perform allergy tests?

Your healthcare provider may perform an allergy test if you have allergy symptoms that bother you. Providers also perform allergy tests on people who have asthma. The test can identify allergy triggers that can worsen asthma symptoms (allergic asthma).

You may also need an allergy test if you’ve had a severe allergic reaction called anaphylaxis. This potentially life-threatening problem can cause hives or swelling, breathing difficulty and/or a sharp drop in blood pressure that brings on anaphylactic shock.

Your health history, along with allergy testing, determines the cause of a severe reaction. If you’ve had an anaphylactic reaction or are at risk for one, then you may need to carry an epinephrine (adrenaline) auto-injector (EpiPen®) to use when symptoms develop.

How do I know if I need an allergy test?

Allergies affect everyone differently — this means the allergy symptoms you get can be different from those of your friends, even if you have the same allergy.

If you’re allergic to allergens in the air like dust, pollen or pet dander, you may develop allergic rhinitis. Also known as hay fever, this allergic reaction causes:

• Headaches.
• Itchy, watery eyes.
• Nasal congestion, sneezing or runny nose.
• Shortness of breath, wheezing or chronic cough.
• Sore throat.

Food allergy symptoms typically occur within 30 minutes of eating something but may occur up to two hours after. People with food allergies may experience:

• Skin symptoms such as hives, swelling of the face, lips or tongue, or itching.
• Respiratory symptoms like coughing, wheezing, shortness of breath, chest or throat tightness.
• Nausea and vomiting, abdominal pain and cramps, vomiting and diarrhea.
• Cardiovascular symptoms such as pale skin, weak pulse, dizziness or lightheadedness.

People who are allergic to latex, fragrances or metals like nickel may develop an itchy, swollen rash on their skin. You may have:

• Burning sensation on your skin or blisters.
• Hives and swelling.
• Skin rash or itchy skin.

Contact your healthcare provider if you have any allergy symptoms. They can help diagnose what’s causing your allergic reaction and determine if you need an allergy test. It’s important to not dismiss allergic reactions as just a nuisance. Allergic reactions can be unpredictable and become severe even if your first allergic reaction was mild.

What does an allergy test do?

Allergy tests measure your body’s response to specific allergy triggers or allergens. If you have an allergy, your immune system mistakenly identifies the allergen as a threat or invader. It produces antibodies called immunoglobulin E (IgE) to fight off the threat. These antibodies trigger the release of chemicals that cause an allergic reaction.

How should I prepare for an allergy test?

Your healthcare provider may ask you to stop taking allergy medications like antihistamines three to seven days before an allergy test. These medicines can interfere with test results by stopping your immune system’s response to allergens. You should continue to take asthma medication if you need it. Talk to your healthcare provider if you have questions about how to prepare for your test.

What should I expect during an allergy test?

The purpose of skin tests is to see how your body responds to allergens. If you have an allergic reaction, you’ll develop a reaction at the site of the scratch or prick. Mild allergy symptoms such as itchy skin, watery eyes and congestion are common. Most symptoms clear up in one to two hours after the test, but the redness or bumps may remain for several hours. In rare cases, a severe reaction occurs. This is why healthcare providers perform skin allergy tests and food challenges in their offices. A blood allergy test only involves giving a blood sample. Your healthcare provider draws blood from a vein in your arm and then sends it to a lab.

How long does an allergy test take?

It depends on what allergen your provider is testing you for and the type of test. Here’s what you can expect:

• An allergy blood test can take 10 minutes because it only involves giving a blood sample.
• A skin prick test can take three to five minutes per allergen, plus the 15 to 20 minutes you wait to see if a reaction occurs.
• A patch test can also be about three to five minutes per allergen. With this test, you go home and come back a few days later for your provider to check for a reaction.
• An oral challenge test could take three or four hours.

What does a full allergy test consist of?

You may hear people call allergy tests a complete, full or comprehensive panel. They’re probably referring to a test that checks your allergic reaction to several of the most common allergens. For example, this could mean your allergist checks for pollen, ragweed, grass, dust and pet dander, as they’re the most common airborne irritants.

What are the risks of allergy testing?

The potential for an anaphylactic reaction is the more serious risk of allergy testing. This type of reaction is rare. Your healthcare provider prepares for this risk by having emergency epinephrine nearby during allergy testing.

You may feel itchy or sore or begin developing allergy symptoms during allergy skin tests. This is normal and how your provider can determine if you have an allergy. They have medication to give you to help with this.

If you have a reaction to a patch test once you’re home, don’t apply anything to your skin. Your skin may start to itchy under the patch. Ask your healthcare provider what to do if you begin experiencing intense itching or burning while wearing an allergy patch.

When should I get my allergy test results?

You’ll get the results of most allergy tests immediately after testing while at your provider’s office. A patch test can take several days. Results from blood tests sent to a lab may take a week or longer.

What do the results of an allergy test mean?

Allergy test results may be:

• Negative: You aren’t allergic to that substance. It’s rare to get a false (incorrect) negative allergy test result (meaning the test says you don’t have an allergy when you actually do).
• Positive: You’re allergic to that substance. Note that even when tests correctly show that you have an allergy, it doesn’t necessarily mean that you’ll react to that allergen. A false positive test result is possible, especially from a blood (IgE) test. A false positive means the results show you have an allergy when you don’t.

What happens if I have an allergy?

Depending on the allergy, your healthcare provider may recommend one or more of these steps:

• Minimize exposure to allergens: Avoid known allergens if you can. This could mean staying indoors when pollen counts are high due to a pollen allergy. You should take extreme precautions to avoid allergens that can cause severe reactions.
• Take daily allergy medications: Medications like nasal sprays and antihistamines can prevent or reduce allergic rhinitis and other symptoms. Your healthcare provider may recommend other allergy medications depending on your symptoms.
• Get allergy shots: This type of immunotherapy can decrease your immune system’s response to environmental allergens like pet dander. You should get allergy shots for three to five years to experience maximum benefit. Allergy shots can be costly, but they often provide long-lasting relief, even after you receive the full shot series.
• Have a medical alert card: A card or medical alert jewelry lets others know about your severe allergy. It tells them you could have an anaphylactic response to peanuts, bee stings or other allergens.
• Carry an epinephrine injector: Keep this medicine with you at all times if you’re at risk for an anaphylactic allergic reaction.

Do at-home allergy tests work?

Over-the-counter allergy test kits that you buy at your local drugstore or online aren’t very reliable. Some of them don’t test for the right antibodies. You’re also more likely to get a false-positive result, which may lead you to avoid certain substances or foods unnecessarily. It’s better to work directly with a healthcare provider to determine the cause of your allergy symptoms.

Does insurance cover allergy tests?

Healthcare coverage for allergy testing varies depending on your insurance policy. The costs for each type of allergy test also vary. It’s best to check with your insurer about your plan’s policies before testing so you know what you can expect.

At what age is allergy testing accurate?

Adults and children can get an allergy test. Healthcare providers typically don’t conduct skin prick testing on children under 6 months old. Some research shows blood allergy tests can be slightly less accurate in children under 5. Despite this, deciding whether to test children for allergies should be based on your child’s symptoms. Your child’s healthcare provider can help you decide if an allergy test is necessary and if any factors will affect its accuracy.