A food allergy is an exaggerated immune response triggered by eggs, peanuts, milk, or some other specific food.

Allergy to food

In severe reactions, you may have low blood pressure and blocked airways.

Blood or skin tests are sometimes used to confirm that you have an allergy. A double-blind food challenge is one way to diagnose true food allergies. During this test, you and your health care provider will not know what you are eating.  

With elimination diets, you avoid the suspected food until your symptoms disappear. Then you start eating the foods again to see if you develop an allergic reaction.

In provocation (challenge) testing, you eat a small amount of the suspected food under medical supervision. This type of test may cause severe allergic reactions. Challenge testing should only be done by a health care provider.

Never try to cause a reaction or reintroduce a food on your own. These tests should only be done under the guidance of a health care provider -- especially if your first reaction was severe.

The only proven treatment for a food allergy is to avoid the food. Other treatments, including allergy shots and probiotics, have not been proven to help with food allergies.

If your child has a problem with cow’s milk formula, your health care provider may suggest trying a soy-based formula or something called an elemental formula, if it is available.

If you suspect that you or your child has a food allergy, see an allergy specialist.

If you have symptoms on only one area of the body (for example, a hive on the chin after eating the food), you may not need any treatment. The symptoms will likely go away in a brief time. Antihistamines may relieve the discomfort. Soothing skin creams can also provide some relief.

Talk to your health care provider if you think you have had an allergic reaction to food, even if it is only a local reaction.

Anyone who has been diagnosed with a food allergy should carry (and know how to use) injectable epinephrine at all times. If you develop any type of serious or whole-body reaction (even hives) after eating the food:

• Inject the epinephrine.
• Then go to the nearest hospital or emergency facility right away, preferably by ambulance.

Food Allergy and Anaphylaxis Network -- www.foodallergy.org

• Call your local emergency number, such as 911, if you have any serious or whole-body reactions (particularly wheezing or difficulty breathing) after eating a food.
• If your doctor prescribed epinephrine for severe reactions, inject it as soon as possible, even before calling 911. The sooner you inject the epinephrine, the better.
• Anyone who has had an allergic reaction to a food should be evaluated by an allergy specialist.

Breastfeeding may help prevent allergies. Otherwise, there is no known way to prevent food allergies except to delay introducing allergy-causing foods to infants until their gastrointestinal tract has had a chance to mature. The timing for this varies from food to food and from baby to baby.

Once an allergy has developed, carefully avoiding the offending food usually prevents further problems.

Lack G. Clinical practice. Food allergy. N Engl J Med. 2008;359:1252-1260.

Chafen JJ, Newberry SJ, Riedl MA, et al. Diagnosing and managing common food allergies: a systematic review. JAMA. 2010 May 12;303(18):1848-56.