In someone with a food allergy, the immune system has an inflammatory reaction whenever the person eats the allergenic food. Most food allergies present with classic patterns of symptoms. In some people, food allergies show up in specific forms that are a little different.
Symptoms of food allergy can vary widely. Many people develop skin symptoms such as itching, rash, or hives. Others have respiratory symptoms such as asthma, sneezing, cough, and trouble breathing. Gastrointestinal symptoms including cramping, vomiting, and diarrhea are also common. Others experience anxiety, behavior changes, heart palpitations, dizziness, or many other reactions.
Anaphylaxis is a life-threatening reaction that can progess to a sudden drop in blood pressure, narrowing of the airways that makes it difficult to breathe, rash, and swelling. If untreated, anaphylaxis can be fatal. Learn more about food allergy symptoms.
These are the most common ways food allergies are experienced. Sometimes, food allergies cause other types of reactions that look a little different and have their own specific terms.
FPIES is a serious allergic condition that causes gastrointestinal symptoms such as diarrhea, vomiting, weight loss, and failure to thrive in small children just beginning to eat solid food. These symptoms usually begin hours after eating a food and can last for hours. The most common allergens that cause FPIES include:
FPIES can become severe enough that it requires hospitalization due to dehydration. Strict avoidance of the food triggering FPIES is necessary to avoid symptoms.
Children commonly outgrow FPIES by age 3 or 4.
Also known as pollen-food allergy syndrome, OAS occurs in people with hay fever or seasonal allergies. Certain types of pollen have proteins in common with certain raw nuts, fruits, or vegetables. When the person eats the food with similar allergenic proteins, they experience itching and swelling which is typically limited to the mouth, tongue, throat, lips, and sometimes ears. Symptoms are usually fairly mild and do not require treatment. OAS is most likely to develop in older children or young adults. Typically, the food was eaten for years with no problems when OAS begins.
A few of the raw foods most likely to cause OAS include:
People with OAS can typically eat the trigger foods with symptoms if they have been cooked. Cooking changes the proteins enough to avoid the reaction.
In EOE, the esophagus — the tube you swallow food down that brings food to the stomach — becomes inflamed and may narrow, making it difficult to swallow hard or dry foods. Other symptoms can include vomiting and abdominal pain. Small children may refuse to eat. EOE can develop in people of any age. EOE can be caused by environmental allergies, but food allergies are the most common cause.
EOE is a complex and serious allergic disorder. EOE is chronic and can be difficult to treat. Identifying the foods that trigger EOE is difficult. Treatments include elimination diets, swallowed corticosteroids, and proton pump inhibitors (drugs to reduce the amount of stomach acid produced). In children with severe cases that do not respond to other treatments, an elemental diet may be recommended. In an elemental diet, all nutrition is received from a formula containing amino acids, sugars, and oils.