Skip to main content

Search
Nutrition and Fitness

How Do Doctors Test for Food Allergies?

|

How do doctors test for food allergies?
- Debra

Doctors often use a combination of skin testing and blood testing to diagnose a food allergy.

One common skin test is a scratch test. For this test, a doctor or nurse will scratch the skin with a tiny bit of liquid extract of an allergen (such as pollen or food). Allergists usually do skin tests on a person's forearm or back. The allergist then waits 15 minutes or so to see if reddish, raised spots (called wheals) form, indicating an allergy.

If the doctor thinks someone might be allergic to more than one thing — or if it's not clear what's triggering a person's allergy — the allergist will probably skin test for several different allergens at the same time.

When a skin test shows up as positive with a certain food, that only means a person mightbe allergic to that food. In these cases, doctors may want to do additional testing.

To diagnose a food allergy for certain, an allergist might do a blood test in addition to skin testing. This involves taking a small blood sample to send to a laboratory for analysis. The lab checks the blood for IgE antibodies to specific foods. If enough IgE antibodies to a particular food are in the blood, it's very likely that the person is allergic to it.

If the results of the skin and blood tests are still unclear, though, an allergist might do something called a food challenge. During this test, the person is given gradually increasing amounts of the potential food allergen to eat while the doctor watches for symptoms.

Skin tests may itch for a while. If your child undergoes one, the allergist might give you an antihistamine or steroid cream for your child to use after the test to lessen the itching.

Reviewed by: Steve Dowshen, MD
Date reviewed: April 2012

License

Note: All information is for educational purposes only. For specific medical advice, diagnoses and treatment, consult your doctor.

© 1995–2014 The Nemours Foundation/KidsHealth. All rights reserved.

Should your child see a doctor?

Find out by selecting your child’s symptom or health condition in the list below:

Summer 2014: Good Growing Newsletter

In This Issue

  • Understanding the Power and Influence of Role Models
  • Legal Marijuana Means Greater Poisoning Risks for Children
  • Why Choose Pediatric Emergency Care?

Download Summer 2014 (PDF)

Videos

Miracle Makers 2014 3:07:00Expand
6.6.14

The 30th annual Miracle Makers fundraising special aired on KOMO 4 TV on June 6, 2014. The special takes us on a journey through the hopes, fears, victories and challenges facing patients at Seattle Children's. Cosponsored by Costco Wholesale and KOMO 4. 

Play Video
Overcoming the Odds: A KING 5 TV Children's HealthLink Special 0:44:45Expand
12.30.13

In the spirit of the holidays, patients, parents and doctors share inspirational stories of healing and hope. From surviving heart failure and a near-death drowning to battling a flesh-eating disease, witness how the impossible became possible thanks to the care patients received at Seattle Children's Hospital.

Play Video
Miracle Season 2013 0:57:06Expand
12.11.13

Miracle Season, hosted by Steve Pool and Molly Shen, aired Dec. 8, 2013, on KOMO 4 TV. The annual holiday special celebrates the remarkable lives of Seattle Children's patients.

Play Video