In the test, a drop of a purified liquid form of the allergen is either dropped onto the skin and the area pinched with a small plastic device, or a small amount of allergen is injected just under the skin. This only pinches a little. After about 15 minutes, if a reddish area, like a mosquito bite, appears at the injection site, the test is positive. A child must also have symptoms for a definitive diagnosis. For example, a toddler who has a positive test for dust mites AND sneezes frequently while playing on the floor would be considered allergic to dust mites.
Skin tests are less expensive and more accurate than blood tests for allergies.
But blood tests may be required in children with skin conditions or those who are extremely sensitive to a particular allergen. The Nemours Foundation is a nonprofit organization devoted to children's health and is the largest physician practice delivering subspecialty pediatric care in the United States. Inc. All rights reserved. KidsHealth and KidsHealth.org are Service Marks of The Nemours Foundation. All information on KidsHealth is for educational purposes only.