1. Health
You can opt-out at any time. Please refer to our privacy policy for contact information.

Prick Tests


Updated May 14, 2008

Prick Tests

Prick tests are one method for diagnosing food allergies.

Photo © A.D.A.M.


A prick test is often used by allergists when a patient has clear allergy symptoms but is not certain which food is causing those symptoms (or whether the symptoms are caused by a food at all). They are often used when patients have hives, eczema, or hay fever symptoms.


20 to 30 minutes.


Prick tests are among the quickest allergy tests available. They are reasonably inexpensive, allow allergists to test a number of potential allergens at one time, and are usually not painful.


Prick tests are considered less sensitive than some other allergy tests, and a negative prick test may be followed up with other, more sensitive tests if a practitioner strongly suspects an allergy. Prick tests are generally not used when a reaction is considered life-threatening.

"False positives," where a food someone tolerates well returns a positive test result, do sometimes occur. An allergist will make a final diagnosis of an allergy based not just on the prick test, but also on the patient's symptoms and history.

How it works:

Prick tests (sometimes called scratch tests) are performed on the skin of the forearm or the back. Allergists put a small amount of an extract of a potential allergen into a shallow scratch. Within twenty to thirty minutes, a positive result will show as a hive, or wheal, on the scratch. The size of the hive may correlate with the intensity of the allergic reaction.

In the event of a severe reaction, the allergist will administer a rescue medication such as epinephrine or an antihistamine. Severe reactions to a prick test, however, are uncommon. (This is why they are generally not used to confirm life-threatening reactions -- blood tests are much safer for that purpose.)

Related Video
Pretzel-Crusted Chicken Tenders
  1. About.com
  2. Health
  3. Food Allergies
  4. Diagnosing Food Allergies
  5. Prick Tests - Scratch Test - Allergy Prick Tests and Scratch Tests

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.