About Food Allergies

Conditions Related to Food Allergy

The disorders described below may produce symptoms that are similar to those of food allergies. However, some of these conditions do not involve IgE (immunoglobulin E), the antibody that causes potentially life-threatening reactions in people with food allergies. In some cases, a person may have both a food allergy and a related condition, such as eosinophilic esophagitis.

Eosinophilic Esophogitis
Food Protein-induced Enterocolitis Syndrome
Oral Allergy Syndrome
Food Intolerances
Lactose Intolerance
Celiac Disease

Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) causes large numbers of eosinophils, a type of white blood cell, to gather in the esophagus (the tube that connects the mouth to the stomach). As a result, the lining of the esophagus becomes inflamed, making it difficult for food to go down. EoE can be triggered by certain foods.  

Symptoms vary, depending on age. With infants and toddlers, families often note feeding difficulties, irritability, and occasionally poor weight gain. Older children typically have regurgitation, vomiting, heartburn and “belly pain.” Teenagers and adults may have chest pain, difficulty swallowing and a feeling that food “gets stuck” when they swallow. Some individuals complain that it takes a long time to eat meals and that large quantities of water are needed to help swallow food. They may also complain of feeling full rapidly and may stop eating before finishing a meal.

Once a diagnosis of EoE is confirmed, food allergy testing is typically performed to determine if a food is triggering the condition.

To learn more about EoE, please visit the website of the American Partnership for Eosinophilic Disorders.

Food Protein-induced Enterocolitis Syndrome

Food protein-induced enterocolitis syndrome (FPIES) is a serious, non-IgE-mediated type of food allergy. FPIES is usually triggered by cow’s milk or soy, though some cereal grains, especially rice and oat, and other foods may cause it. The symptoms typically include severe vomiting and diarrhea. Reactions are often delayed by 2-3 hours after the trigger food is eaten.

Standard food allergy tests are not used for diagnosing FPIES. The primary test medical professionals use to diagnose this disease is an oral food challenge with the suspected trigger food. In most cases, FPIES is resolved by the age of three.

More information about FPIES is available from the FPIES Foundation and the International Association for Food Protein Enterocolitis.

Oral Allergy Syndrome

Oral allergy syndrome (OAS), also known as pollen-food syndrome, is a term used to describe itchy or scratchy mouth symptoms caused by raw fruits or vegetables in people who also have hay fever. Symptoms are typically limited to the mouth. This reaction is caused by an allergic response to the pollen that crosses over to similar proteins in the foods. Because these proteins are sensitive to heating, most people affected by OAS can eat cooked fruits or vegetables. Symptoms usually resolve within minutes after the food is swallowed or removed from the mouth, and treatment generally is not necessary.

OAS typically presents in older children, teens or young adults. Often, patients have been eating the offending foods without problems for many years.

Common pollen-food associations*

  • Birch: apple, carrot, peach, plum, cherry, pear, almond, hazelnut
  • Grasses: tomato
  • Ragweed: melons, zucchini, cucumber, kiwi, banana

* These are potential associations. Not every individual allergic to pollen develops symptoms with cross-reacting fruits or vegetables. Individuals may react to a few but not all of the above.

Food Intolerances

With the exception of celiac disease (see below), food intolerances do not involve the immune system. Although food intolerances may cause some of the same symptoms as a true food allergy, they cannot trigger anaphylaxis, a potentially life-threatening reaction. Common intolerances include:

  • Lactose Intolerance
    Lactose intolerance occurs when a person’s small intestine does not produce enough of the lactase enzyme. As a result, affected individuals are not able to digest lactose, a type of sugar found in dairy products.

The symptoms of lactose intolerance typically occur within 30 minutes to two hours after ingesting dairy products. Large doses of dairy may cause increased symptoms.

  • Celiac Disease
    An adverse reaction to gluten is known as celiac disease or “celiac sprue.” This chronic digestive disease requires a lifelong restriction of gluten, which is found in wheat, rye, barley, and perhaps oats. People with celiac disease must strictly avoid these grains and their by-products.

When people with celiac disease eat gluten, they experience an immune reaction in the small intestine. IgE, the antibody responsible for life-threatening reactions (anaphylaxis) does not play a role in this disorder. However, the immune response in celiac disease may damage the lining of the small intestine, preventing proper absorption of the nutrients in food. Over time, patients may become malnourished.

Celiac disease can cause many symptoms, including bloating and gas, diarrhea, constipation, headaches, itchy skin rash, and pale mouth sores, to name a few. The symptoms may vary among affected individuals.

More information about celiac disease is available from the Celiac Disease Foundation and Beyond Celiac.