Food Allergies

Food allergy symptoms occur most often in babies and children but can appear at any age. Foods that you have eaten for years without problems can cause allergies.

An allergy occurs when something causes your body’s natural defenses to overreact. More than 50 million Americans have an allergy of some kind, but food allergies are rare. Up to 4 percent of adults have food allergies.

By using caution and carefully following an allergist’s advice, you can bring food allergy under control. Please contact your allergist with further questions and concerns about food allergy treatment.

Food allergy causes:

The body’s natural defense network is called the immune system. It keeps you healthy by fighting off infections and other dangers to good health. Most people have no problem eating many kinds of foods. An allergic reaction occurs when the immune system attacks a specific food or something in a food by mistake. This battle causes:

  • Blood vessels to swell up,
  • Smooth muscles to contract, and
  • Skin areas to become red, itchy and swollen

Why do I have food allergy?

If both your parents have allergies, you have about a 75 percent chance of being allergic. If one of your parents is allergic, or if one of your relatives from either side has allergies, you have a 30-40 percent chance of having some form of allergy yourself. If neither parent has allergy, the chance is only 10-15 percent.

The amounts of a food or a kind of food you eat, and how often you eat, it may be important to why you become food allergic.

Which foods are most likely to cause allergy?

Almost any food can start an allergy. Peanuts, tree nuts and shellfish often cause severe food allergies.

Someone allergic to a food may also react to related foods. A person allergic to walnuts may also react to pecans. Persons allergic to shrimp may also react to crab and lobster. A person allergic to peanuts may have problems with soy, peas or certain kinds of beans.

Most food allergy patients only react to one or two foods. Someone allergic to pecans may not have to stop eating all nuts. This should be discussed with your allergist.


Food Allergy Symptoms

Studies suggest that food allergies affect as many as 15 million Americans. Food allergy reactions can cause a variety of symptoms that range from mild to severe, including anaphylaxis, a serious reaction that is rapid in onset and may cause death. These reactions can be the result of the immune system producing an antibody, Immunoglobulin E (or IgE) to a certain food, or the result of a non-IgE reaction, which is cell-mediated. Some examples of non-IgE reactions include milk or soy intolerances, celiac disease, Food Protein Induced Enterocolitis (FPIES), and eosinophilic disorders.

Virtually any food can cause an adverse reaction, though eight foods (egg, milk, peanut, tree nuts, fish, shellfish, wheat, and soy) account for approximately 90 percent of all reactions.

Symptoms can involve the skin, gastrointestinal, cardiovascular, and/or respiratory tracts. Mild symptoms can include an itchy mouth, isolated hives, or mild nausea or discomfort. More severe food allergy symptoms include:

  • Vomiting
  • Stomach cramps
  • Indigestion
  • Diarrhea
  • Hives all over the body
  • Shortness of breath
  • Wheezing
  • Repetitive cough
  • Tight, hoarse throat; trouble swallowing
  • Swelling of the tongue and/or lips
  • Weak pulse
  • Pale or blue coloring of skin
  • Dizziness or confusion

Epinephrine is the first-line treatment for anaphylaxis. Other medications, such as antihistamine and corticosteroids, may be prescribed to treat symptoms of a food allergy, but it is important to note that there is no substitute for epinephrine – this is the only medication that can reverse the life-threatening symptoms of anaphylaxis.

Symptoms of a food allergy typically occur within the first few minutes following ingestion of the food allergen, though in some cases, the reaction may be delayed by 4 to 6 hours, or even longer if the reaction is not IgE-mediated (i.e., FPIES).

Certain symptoms can point to a particular type of reaction –  symptoms such as itchy mouth and throat that could signal Oral Allergy Syndrome (OAS), which occurs in individuals who have hay fever and eat certain raw fruits or vegetables that cross-react with pollens.

Delayed (two to eight hours) allergic reactions to certain foods such as milk and soy among infants and young children could be related to FPIES, a reaction typically characterized by vomiting and diarrhea.

Some mild food related symptoms may be caused by food intolerance rather than an allergic reaction. If you have a reaction to what you believe is a food, consult with your allergist for a diagnosis and to determine a treatment and management plan.


Credit: American College of Allergy, Asthma & Immunology