What Is a Skin Prick Test?

To determine if your child has allergies, your doctor might recommend a skin prick test that involves piercing the skin with small drops of allergens.

What Is a Skin Prick Test?

If your doctor thinks your child shows signs of allergies, he might recommend a skin prick test. This test, also called a scratch test, can detect allergies for about 40 foods and substances. The test results can help you manage your child's allergic reactions to common allergens such as mold, pollen, and pet dander, and prevent life-threatening emergencies if your child has an allergic reaction to insect venom, latex, or nuts.

    What to Expect From Skin Prick Tests

    A number of over-the-counter and prescription medications, such as antihistamines, can prevent accurate results from a skin prick test. Before scheduling a test, always inform your doctor of all the medications your child is taking. Your child may need to stop using these medications for up to two weeks before the test.

    The test is done in the doctor's office, often by a nurse. Your child's arm or upper back will be used as the test site. After cleaning the test site with alcohol, the nurse may use a pen to draw marks on the skin for each drop of potential allergen to be placed on it. Each mark will then be pricked with a needle or pin that contains a tiny amount of a specific allergen. To ensure accurate results, the scratch test will include histamine and glycerin, which are used as controls to make sure your child's skin is reacting normally. Histamine normally causes a skin reaction in most people, but glycerin usually causes no reactions, so if your child's skin reacts to glycerin, it may indicate that the skin is too sensitive for a skin prick test to work.

    After about 15 minutes, the nurse will observe each mark for raised red bumps that resemble mosquito bites (also called wheals). Any bump will be measured and recorded so your doctor can review the results and then develop a treatment or prevention plan. Allergies are often triggered by certain foods (milk, eggs, nuts), weed pollen, dust, pet dander, bee venom, penicillin, and latex.

    The most common reactions to a skin prick test are itchy, swollen bumps on the skin that usually subside in a few hours and disappear in a few days. In rare cases, the test can result in an extreme reaction if your child has a severe allergy to one of the tested substances. This is why these tests are done at a doctor's office, where emergency equipment and medications are on hand to counteract anaphylaxis, which causes breathing difficulties.

    Copyright 2012 Meredith Corporation.

    All content on this Web site, including medical opinion and any other health-related information, is for informational purposes only and should not be considered to be a specific diagnosis or treatment plan for any individual situation. Use of this site and the information contained herein does not create a doctor-patient relationship. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.