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Allergy Skin Tests – An Overview

Verified By Dr Pranoti Deshpande April 7, 2021 4269 0
Allergy Skin Tests
Allergy Skin Tests (1)

Allergy skin tests involve exposing your skin to suspected allergens (substances that cause allergy) and then looking for the signs and symptoms of an allergic reaction.

About Allergy Skin Tests

If you want to avoid allergies, you must first identify the substances that cause allergic reactions in your body. Allergy skin tests help you identify the allergen(s).

During skin allergy tests, your doctor will expose your skin to the common allergy-causing agents. He/she is likely to introduce extracts of mold, pollen, dust mites, food items, pet dander, etc., on your skin in concentrated liquid form and look for allergic reactions.

If you are allergic to any particular or multiple substances, your skin will react (allergic reaction). In most cases, allergic reactions appear as rashes, redness, bumps, and itchiness like mosquito bites on your skin. This is how you can understand if or not you are allergic to something.

Moreover, the results of allergy tests are likely to help your doctor decide on an allergy treatment plan for you, including medications, avoiding the allergens, or immunotherapy (allergy shots).

Why does your doctor recommend allergy skin tests?

Your doctor is likely to recommend allergy skin testing to diagnose specific allergies, including allergic asthma, allergic rhinitis (hay fever), eczema (dermatitis), penicillin allergy, food allergies, and bee venom allergy, to name a few.

Also Read About: Squamous Cell Carcinoma of The Skin

What are the risks associated with allergy skin tests?

The risks or side effects of allergy skin tests include the following:

  • One of the most common side effects of skin testing for allergy is the appearance of red, swollen, and itchy wheals (bumps) on your skin.
  • In some cases, the swelling might not be visible during the skin test, while in other cases, the irritation happens to develop after a couple of hours after the test and stays for a few days.
  • In rare cases, the tests can lead to an immediate and severe allergic response. Therefore, it is highly advisable to take allergy skin tests at a recognised  healthcare facility.

How to prepare for the allergy skin tests?

Here is how you can prepare for an allergy skin test:

  • Your doctor is likely to ask you about your signs and symptoms, family history, medical history, medications you have been taking, and any underlying health concerns you may have..
  • Medications can affect your test results in many ways. Some of them can counter allergies, while some are likely to aggravate your symptoms and lead to severe allergies during the procedure. This can lower the accuracy of test results. Before fixing an appointment for allergy skin tests, inform your doctor about the OTC and prescription drugs you have been consuming, especially antihistamines, medications for heartburn, and antidepressants.
  • Different medications take different time spans to leave your system. Therefore, your doctor is likely to suggest you stop taking such medicines around 7 to 10 days before the test. For example, if you have been taking antihistamines, your doctor may ask you to discontinue them at least 3 to 7 days before the examination.

What can you expect during the allergy skin tests?

You will have to go to a  healthcare facility to take allergy skin tests. Your doctor will conduct the test and interpret the results. The entire process is most likely to take around 20 to 40 minutes. Some tests identify immediate allergic responses where symptoms develop within a few minutes of exposure to the allergy-causing agent, while others identify delayed allergies that appear over time.

There are different types of allergy skin tests:

Skin prick test: Also known as a scratch or puncture test, it detects immediate allergic responses to around 50 different types of allergens at a time. The commonly identified allergens include – pollen, animal dander, fungus, food, and dust mites. If you are an adult, your doctor is likely to perform this test on your forearm. For kids, the upper back is the preferred location.

Skin tests for allergies are not painful. Although your doctor uses lancets (needles) to prick the surface of your skin, those hardly penetrate your skin. All you will feel is mild discomfort for a moment without any bleeding.

To begin the test, your doctor will prepare the site by cleaning it with alcohol. He/she will then mark your skin to administer different allergens at different locations, using separate lancets.

To find out if your skin is reacting normally or not, your doctor might scratch two additional chemicals on the surface of your skin. It includes:

  • Histamine: This chemical causes a skin reaction in most people. If your skin does not respond to histamine, your allergy skin test results might be incorrect.
  • Saline or glycerine: Most people do not react to these chemicals. However, if you happen to respond to these, you most likely have very sensitive skin. In such cases, your doctor will interpret your test results carefully to avoid an incorrect diagnosis.

After the test is complete, you will have to wait for around 15 minutes. Your doctor will then examine your skin for the signs and symptoms of an allergic reaction(s).

If you have an allergic reaction to any of the allergens, you will develop itchy, red bumps on your skin. Your doctor will measure the size of the wheals and register the inference. And then remove the marks by rubbing them off with alcohol.

Skin injection test: It is an intradermal test where your doctor will administer the allergen into your skin using an injection. After about 15 minutes, he/she will examine the site of injection to detect allergic reactions. Your doctor will recommend the skin injection test if he or she suspects penicillin or insect venom allergy.

Patch test: If your doctor suspects that you may have contact dermatitis (a skin condition causing skin inflammation upon contact with an allergen), he/she is likely to recommend a patch test. During this test, your doctor will apply the allergens to several (20 to 30) patches and place them on your skin. The allergens might include – preservatives, perfumes, medications, resins, hair colors, and metals.

As a patch test can diagnose delayed allergic reactions, your doctor will ask you to keep those patches on your skin for around 48 hours. Your doctor will also restrict you from bathing and strenuous physical activities. After 48 hours, you will have to go to your doctor’s clinic, where he/she will remove the patches. If you have an allergy, your skin will be irritated by the corresponding patch(s).

What are the possible results of the allergy skin tests?

In case of an intradermal or prick test, you will get the results before leaving the doctor’s clinic. However, the outcome of a patch test might take a few days. If your test results are positive, you might be allergic to a given allergen(s). The bigger the bumps, the greater is your skin sensitivity. If your test results are negative, you might not be allergic to the substances used in the test.

When to see a doctor?

If you experience itchiness, redness, or raised rashes on your skin that do not go away on their own, visit your doctor as soon as possible.


Allergy skin tests might not be accurate all the time. These can be false-positive (showing a positive report when there is no allergy) or false-negative (conferring a negative result for an agent you are allergic to), depending on various factors. With test results that identify your allergens and a treatment plan to help you take control, you’ll be able to reduce or eliminate allergy signs and symptoms.

Frequently Asked Questions (FAQs)

  1. Which medical professional or doctor tests the skin for allergies?

Allergy specialists or dermatologists perform allergy skin tests, diagnose the conditions, and treat them.

  1. Are allergy skin tests safe?

As doctors administer a small amount of allergy-causing agent(s) into your skin, these tests are safe.

  1. What are the side-effects of immunotherapy shots for allergy?

One of the most common side effects includes swelling or redness at the injection site. However, some people might also experience the following symptoms:

Verified By Dr Pranoti Deshpande
Consultant Dermatologist, Apollo Hospitals, DRDO Kanchanbagh, Hyderabad

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