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Allergy Skin Tests: How Do Doctors Check for Allergies?

Allergy Skin Tests: How Do Doctors Check for Allergies?

In order to lower your risk of severe allergic reactions, you need to undergo allergy testing. The types of allergy testing available vary depending on what suspected allergies you might have, as well as the current state of your health.

Allergy tests can also be done before surgery, in order for doctors to know if you may be allergic to anesthesia. For people who will be given the tetanus toxoid vaccine, allergy testing is important to rule out any allergic reactions with the vaccine.

Some people are even allergic to latex, or the material used in surgical gloves. If you have no idea that you have a latex allergy, your health may be at risk if you undergo an operation or a medical procedure that involves latex gloves.

What Are the Different Types of Allergy Testing?

Skin tests are the most common type of allergy testing. A skin test helps identify what allergens can cause an allergic reaction. Here are the different types of skin tests that you might undergo:

Skin prick test

As the name suggests, a skin prick test involves applying a drop of allergen extract on your forearm, and scratching the skin with a small needle or lancet. The lancet barely scratches the surface of your skin, so you should not experience any pain during this test. This can be done for up to 50 different allergens at once, and a new lancet will be used for each allergen.

If your skin shows any bumps, similar to a mosquito bite, then you have an allergy. The intensity of your allergy varies depending on the size of the bump that appears. Once the test is done, your skin will be cleaned with alcohol to remove the allergens.

This test can identify if you are allergic to pet dander, certain foods, pollen, and dust mites. The entire process takes less than an hour and is usually done by a doctor who then records the results. This is a painless process that can help quickly identify what allergies you might have. They may also refer you to an allergist or an immunologist.

Skin prick tests can also be used to check for allergies to certain vaccines, such as the influenza vaccine or hepatitis B vaccine.

Skin injection test

A skin injection test involves injecting a small amount of allergen into the skin of your arm. After about 15 minutes, the results will be checked to see if there is a reaction. This is commonly used to check for an allergy to insect venom or penicillin.

Patch test

Patch tests are done in order to check for contact dermatitis or an allergic reaction that occurs when your skin gets in contact with a certain substance. What makes patch tests different is that these can detect delayed allergic reactions.

Unlike the skin prick test and the skin injection test, a patch test does not involve any needles. Instead, it uses patches that contain allergens which are then applied to the skin. A person can be tested for up to 30 different types of allergens at one time.

While the test is being done, you will need to avoid bathing or activities that cause you to sweat heavily.

The patches need to stay on your skin for 48 hours, and afterward they will be removed. Based on your skin’s reactions, your doctor can identify which substances you are allergic to.

This allergy test helps check for an allergy to:

  • Latex
  • Certain medications
  • Fragrances
  • Hair dye
  • Resins
  • Metals

Skin Test Warnings

It is important to note that skin tests are not always 100% accurate. It is possible for a false positive or a false negative to occur. You can even get tested a second time and get different results. Sometimes, you may even be allergic to a substance during a test, but not show any reactions if you get exposed to it in everyday life.

This is why your medical history is also taken into consideration when your doctor diagnoses you with an allergy.

Blood test

A blood test is another way to get tested for allergies. This is usually done if the person is not able to undergo a skin test.

Here are some of the possible reasons for a blood test:

  • If the patient is taking medication that interferes with a skin test
  • The patient has a severe skin problem such as eczema or psoriasis
  • Testing might cause a very severe reaction in the patient

During a blood test, a blood sample will be taken and sent to the laboratory for testing. Unlike skin testing, the process can take a few days before there are any results.

Blood tests for allergies can help detect an allergy to:

  • Pollen
  • Molds
  • Dust mites
  • Animal dander
  • Insect stings
  • Certain medicines
  • Certain food.

Other Types of Allergy Tests

There are two other types of allergy test that are sometimes done. The first one is what’s called an oral challenge test.

Oral challenge test

In an oral challenge test, you will be asked to take a capsule that contains the food that is being suspected. If you show a positive reaction, then your doctor immediately gives treatment for the allergic reaction.

Elimination diet

This involves eliminating any suspected foods from your diet and checking to see if anything changes. Afterward, the foods are introduced one at a time, in order to check for an allergic reaction.

These types of tests can be risky, especially for those with a severe food allergy. This is the reason why they are not always done.

Key Takeaways

These different types of allergy testing can provide you and your doctor some useful information when it comes to your health. Once you can identify what your allergies are, you can take steps to avoid those allergens, or undergo treatment in order to relieve any symptoms and allergic reactions that you might have.

Allergic reactions to different substances can range from the mild to severe, and the treatment likewise. It is also important to understand your family history as those with allergies may often have a family member who also suffers from the same condition.

Learn more about Allergies here.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

How Do Doctors Test for Allergies? (for Parents) – Nemours KidsHealth, https://kidshealth.org/en/parents/allergy-testing.html#:~:text=The%20two%20main%20types%20of,small%20scratch%20on%20the%20skin., Accessed July 3 2020

Allergy skin tests – Mayo Clinic, https://www.mayoclinic.org/tests-procedures/allergy-tests/about/pac-20392895, Accessed July 3 2020

Allergy Testing | About Allergy Test | ACAAI Public Website, https://acaai.org/allergies/allergy-treatment/allergy-testing, Accessed July 3 2020

Allergy Tests: When you need them and when you don’t | Choosing Wisely, https://www.choosingwisely.org/patient-resources/allergy-tests/, Accessed July 3 2020

Food Allergy Testing: MedlinePlus Medical Test, https://medlineplus.gov/lab-tests/food-allergy-testing/, Accessed July 3 2020

Food Allergy – Harvard Health, https://www.health.harvard.edu/a_to_z/food-allergy-a-to-z, Accessed July 3 2020

Allergy Overview – Harvard Health, https://www.health.harvard.edu/a_to_z/allergy-overview-a-to-z, Accessed July 3 2020

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Written by Jan Alwyn Batara Updated May 31
Medically reviewed by Jobelle Ann Dela Cruz Bigalbal, M.D.
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