Allergy Skin Test

Scratch Test · Skin Prick Test · Skin Patch Test

The Basics

An allergy skin test exposes the skin to possible allergy-causing substances (allergen) to identify which of these substances trigger an allergic reaction in a person.

Your doctor determines when and how often it is appropriate for you to do this test. This test is useful to help your doctor diagnose a number of conditions such as:

  • hay fever (allergy to inhaled allergens such as tree, grass pollens, molds, dust)
  • allergic rhinitis
  • dermatitis
  • asthma that is triggered by allergens
  • food, penicillin, bee sting allergies

This test may not be recommended if you take medications that can interfere with the results (e.g., antihistamines, some antidepressants, some heartburn medications), have a serious skin condition, or may be highly sensitive to the test allergens. In these cases, your doctor may recommend blood tests. Some people may be able to stop medications that affect the test before having the test. Your doctor will suggest what would be best for you.

A skin prick test or scratch test.
A skin prick test or scratch test.

Risks and precautions

Allergy testing is usually a straightforward and safe procedure. However, there are some risks of complications or side effects, including:

  • hives (swollen, red, itchy bumps on the skin)
  • anaphylaxis reaction (an immediate, life-threatening allergic reaction)

It is important that you understand all the risks of complications and side effects of the allergy skin test, and what you or your doctor can do to manage them. For example, your doctor may suggest a corticosteroid cream (e.g., hydrocortisone) to treat hives. Make sure that your doctor is aware of all your concerns.

If you experience symptoms of a severe allergic reaction (e.g., shortness of breath; wheezing; or swelling of the mouth, tongue, or face) within a few days after skin allergy tests, get immediate medical attention.

Before the test

There are no specific preparations before the test. Your doctor will likely obtain a detailed medical history from you and conduct a physical examination before starting the test. It is important to note that taking some medications (e.g., antihistamines, some antidepressants, some medications for heartburn) can lead to a false negative result.

If you are taking any prescription or over-the-counter (non-prescription) medications, supplements, or herbal products, make sure you inform your doctor or pharmacist. Ask them whether it is necessary for you to stop taking any of these medications and products before an allergy skin test. It is also important to tell them if you have allergies to certain medications or have certain medical conditions.

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The contents of this health site are for informational purposes only. Always seek the advice of your physician or other qualified healthcare provider regarding any questions you may have about a medical condition.

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