Ask a Doctor

Q: How do I know if I have a food allergy or food intolerance?

A: Some of the symptoms of food intolerance and food allergy are similar, but the differences between the two are very important. Eating a food you are intolerant to can leave you feeling miserable. However, if you have a food allergy, your body’s reaction to this food could be life-threatening.

A food intolerance response takes place in the digestive system. This could be due to enzyme deficiencies, sensitivity to food additives or reactions to naturally occurring chemicals in foods. Often, people can eat small amounts of the food without causing problems.

A food allergic reaction involves the immune system. Your immune system controls how your body defends itself. For instance, if you have an allergy to cow’s milk, your immune system identifies cow’s milk as an invader or allergen. Your

immune system overreacts by producing antibodies called Immunoglobulin E (IgE). These antibodies travel to cells that release chemicals, causing an allergic reaction. Each type of IgE has a specific “radar” for each type of allergen. Symptoms of allergic reactions to foods are generally seen on the skin (hives, itchiness, swelling of the skin). Gastrointestinal symptoms may include vomiting and diarrhea. Respiratory symptoms may accompany skin and gastrointestinal symptoms, but don’t usually occur alone. On the more severe side of an allergic reaction is anaphylaxis. Anaphylaxis is a serious allergic reaction that happens very quickly. Symptoms of anaphylaxis may include difficulty breathing, dizziness or loss of consciousness. Without immediate treatment (an injection of epinephrine (adrenalin)) the outcome can be fatal.

Skin testing can identify food allergies, but cannot identify food intolerances. For this, your allergist will suggest a food elimination diet to try to identify what may be the cause of your symptoms

— Dr. Curt Chaffin, The Allergy & Asthma Group of Galen; member, Chattanooga-Hamilton County Medical Society