Food allergy is a reaction by the immune system that occurs quickly after eating a food. Symptoms occur with ingestion of even a tiny amount of a food and can range from rash or mild itching of the mouth and tongue to life-threatening and life-ending reactions. Many people who think they have a food allergy actually have food intolerance. Food allergy is estimated to affect six to eight percent of children under five, and three to four percent of adults. 

Intolerances to food will affect most people at some point in their lives. For example, lactose intolerance occurs when your body can’t break down milk sugar leading to bloating, cramping and diarrhea. While food intolerances can be uncomfortable they are less serious than food allergy and are not life-threatening. 

How do you determine if you have a food allergy to a specific food? Understanding the symptoms of an allergic reaction is important. In allergic reactions, symptoms develop within seconds to a few hours of ingesting the food. Symptoms occur each time you ingest the food allergen. In fact, 85% of food allergic reactions occur have ingesting the same eight foods: milk, egg, wheat, soy, peanut/tree nuts, fish and shellfish. Symptoms can range from mild to severe—itching in the mouth; hives or eczema; swelling lips, face or tongue; trouble breathing; diarrhea, vomiting and abdominal pain; dizziness and fainting are all symptoms of allergic reactions. Anaphylaxis is a severe, life-threatening allergic reaction to foods. 

Rachel Story, MD, Allergist at NorthShore, highlights some approaches your physician might take to determine if you suffer from a more mild food allergy and what might be triggering your reactions:

• History. A thorough history of reactions and the foods ingested in 2-3 hours prior to the reaction is important in diagnosis of food allergy.
• Food diary. Your physician might ask you to start keeping a food diary for a period of time. Your diary will track what you eat, when you eat it and how you feel after eating certain foods.
• Skin test. In a skin test, purified extracts of the suspected food will be placed on your back or arm and then the skin will be pricked with a skin-testing device to allow a small amount of the food to penetrate your skin. If you react with a raised bump you may have an allergy to that food. 
• Blood tests. Blood tests can be performed to see if you have allergic antibodies to specific foods in your blood. These are often used with a skin test to identify food allergies.  

Food allergy can cause a severe reaction called anaphylaxis.  Symptoms of anaphylaxis include swelling of the airways with throat closing or difficulty breathing, a drop in blood pressure, rapid pulse and fainting. This type of reaction must be treated immediately as it could result in death. All people with suspected food allergy should be evaluated by a physician as they may need to carry medications to treat accidental ingestions of food allergens. Over-the-counter antihistamines such as diphenhydramine (Benadryl) and cetrizine (Zyrtec) are used to treat mild reactions. Severe reactions are treated with an injection of epinephrine that can be administered using an epinephrine autoinjector (EpiPen, AuviQ).

There are currently no FDA-approved treatments for food allergy. However, much promising research is ongoing and there is hope for a treatment for food allergy in the next 5 to 10 years. 

Are you allergic to a food? How did you discover your food allergy?