Reactions to food are common, and can be divided into two categories, those caused by food allergy and all other reactions. Food allergies develop when the body's immune system has an abnormal reaction to one or more proteins in a food. Food allergies can lead to serious or even life-threatening allergic reactions. Food allergies can be further divided into “classic” and “non-classic” types. Other food reactions are not caused by the immune system. These reactions cause unpleasant symptoms and are far more common than food allergies. Examples include lactose intolerance, heartburn (gastroesophageal reflux), bacterial food poisoning, and sensitivity to caffeine.
Although 20-30% of people report food allergies, only 6-8% of children and 3-4% of adults have “classic” food allergy. The most common foods causing allergy are cow’s milk, egg, peanuts, soy, wheat, tree nuts, fish, and shellfish.
In people with "classic" food allergies symptoms typically occurs quickly, within minutes to two hours after eating. The most common symptoms of food allergy include:
Skin: Itching, flushing, hives (urticaria), or swelling (angioedema)
Eyes: Itching, tearing, redness, or swelling of the skin around the eyes
Nose and mouth: Sneezing, runny nose, nasal congestion, swelling of the tongue, or a metallic taste
Lungs and throat: Difficulty getting air in or out, repeated coughing, chest tightness, wheezing, increased mucus production, throat swelling or itching, hoarseness, change in voice, or a sensation of choking
Heart and circulation: Dizziness, weakness, fainting, rapid, slow, or irregular heart rate, or low blood pressure
Digestive system: Nausea, vomiting, abdominal cramps, or diarrhea
Nervous system: Anxiety, confusion, or a sense of impending doom
Some individuals suffer from “non- classic” food allergies. The symptoms of this type of food allergy are usually slower to develop and longer lasting than those of classic food allergies. Symptoms commonly include vomiting, diarrhea, abdominal pain, and/or blood in the stool. Food protein-induced enterocolitis and proctitis/proctocolitis are common types of non-classic food allergy that are seen often in infancy.
A complete and detailed medical history is essential for initiating the proper work up for food allergy. Specific skin and blood testing gives providers added information on determining the likelihood of “classic” food allergy. If a person had a reaction after eating peanuts, but has never reacted to wheat or eggs and eats them regularly, it is not necessary to test for allergy to wheat or eggs. The gold standard test for all food allergy is the oral food challenge, where the food is ingested by the patient in a controlled setting (clinic or hospital) to monitor for reaction. It is important to note that neither the size of the skin prick test nor the level on blood tests translate into severity of allergy. These tests only speak to the likelihood of any reaction.
Once a food allergy is certain, the best treatment is to avoid the food. Patients must carefully check ingredient labels for all food products. The most important aspect of the treatment plan is to have emergency medications available at all times in case of an allergic reaction. In the case of a severe allergic reaction, timely administration of self-injectable adrenaline is the cornerstone of treatment.
How We Can Help
Your Allergy Partners board-certified provider can assist in determining whether or not a food allergy exists, what type of food allergy it is, and what treatment plan is appropriate. Your allergist will help you understand the potential testing options as well as directing you to helpful resources like special food allergy cookbooks, patient support groups, and registered dieticians.