Key Points about Food Allergies

Food allergies occur when the immune system identifies a certain food as harmful, causing the body to release chemicals that cause allergy symptoms.

  • Common food allergies in adults include shellfish, peanuts, tree nuts, and fish
  • Common food allergies in children include peanuts, tree nuts, soy, wheat, eggs, and cow’s milk.
  • Some food allergies can cause symptoms that are irritating but relatively mild, such as throat itching, light headedness, nausea, and swelling
  • Other allergies can cause a severe and life-threatening reaction called anaphylaxis, which is characterized by throat constriction and trouble breathing, rapid pulse, and loss of consciousness

People experiencing anaphylaxis must seek immediate emergency medical treatment. Call your doctor if you have experienced any symptoms of a food allergy following a meal.

Overview

Food allergies occur when the immune system identifies a certain food as harmful, which leads the immune system to produce antibodies, called immunoglobulin E (IgE), that remain on the alert for that food. When you are exposed to the food again, these antibodies attack the “invader” by releasing immune system chemicals such as histamine, which cause allergy symptoms.

Mild to moderate symptoms of food allergies may include a tingling or itching sensation in the mouth, hives or skin rashes, swelling of the tongue, throat or lips, and digestive issues.

Food allergies in some people can cause a serious and life-threatening allergic reaction called anaphylaxis, which is characterized by throat constriction and trouble breathing, a rapid pulse, or a loss of consciousness.

Your doctor can administer tests to identify possible food allergies, prescribe emergency medications to treat anaphylaxis, and help set up a long-term plan to avoid foods that cause your allergic reactions.

Food allergy causes

Food allergies are caused by your immune system identifying a usually harmless food as a dangerous invader. When your immune system makes this identification, it leads cells to release antibodies called immunoglobulin E (IgE), which remain on the alert for that food. When you are exposed to the food again, these antibodies attack the “invader” by releasing immune system chemicals such as histamine, which cause allergy symptoms.

Common food allergies in adults are triggered by:

  • Shellfish, including lobster, crab and shrimp
  • Peanuts
  • Tree nuts, including pecans and walnuts
  • Fish

Common food allergies in children are triggered by:

  • Peanuts
  • Tree nuts
  • Wheat
  • Soy
  • Eggs
  • Cow’s milk

It is not totally known, however, what causes some people to develop food allergies, while others do not.

Food allergy risk factors

You may be more likely to have a food allergy if you:

  • Have a family history of asthma, eczema, or general allergies
  • Have an existing food allergy
  • Are a child, toddler, or infant
  • Have asthma

You may be more likely to experience anaphylaxis from a food allergy if you:

  • Have asthma
  • Are a child or teenager
  • Do not have hives or other allergic reaction skin symptoms
  • Delay using your prescribed epinephrine after being exposed to your existing allergen trigger

Food allergy symptoms

Symptoms of a food allergy usually develop within several minutes or an hour after consuming the food item.

Symptoms may include:

  • A tingling or itching sensation in the mouth
  • Itching, eczema, or hives on the skin
  • Face, tongue, lips or throat swelling
  • Swollen airways, nasal congestion, wheezing, and trouble breathing
  • Digestive problems such as abdominal pain, nausea, vomiting, or diarrhea
  • Lightheadedness, dizziness or fainting

Some food allergies can cause symptoms that are irritating but relatively mild. Other allergies can cause a severe and life-threatening reaction called anaphylaxis.

Symptoms of anaphylaxis include:

  • A tightening of the airways or a swollen throat that restricts breathing
  • Shock, and a dramatic blood pressure drop
  • A rapid pulse
  • Feeling lightheaded, dizzy, or losing consciousness

People experiencing symptoms of anaphylaxis must seek immediate emergency medical treatment.

Food allergy diagnosis

When diagnosing a possible food allergy, your doctor may:

  • Review your physical symptoms, to get an idea of what foods may be causing problems
  • Ask about any family history of allergies to specific foods
  • Administer a skin test. In a skin test, a doctor or nurse will prick your skin to expose you to small amounts of the proteins found in various potential allergens. If you are allergic, you will likely develop a raised bump, or hive, at the injection site on your skin.
  • Perform a blood test to measure your immune system response to various foods
  • Recommend an elimination diet, which involves removing possible food allergens from your diet for several weeks. After a few weeks, you will reincorporate the foods into your diet one at a time, to track which food may be responsible for symptoms.

Food allergy treatment

While there is no cure for allergies, a combination of medications and strategic planning to avoid your allergen triggers can prevent allergic reactions or regulate symptoms if reactions do occur.

Taking over-the-counter antihistamines can relieve symptoms of minor allergic reactions to foods.

For severe food allergies, you may need to carry an emergency epinephrine auto-injector such as EpiPen or Adrenaclick, in the event of an allergic reaction.

The following measures can also help avoid allergic reactions to foods:

  • Carefully read food and drink labels to make sure you always know what you are consuming
  • Wear a medical alert bracelet or necklace stating your allergy in the event of a reaction that compromises your ability to communicate
  • Alert your server at restaurants of your food allergies
  • Plan meals before leaving the house, and pack food for yourself if attending an event that may not have allergen-free food

Consult your doctor to establish a comprehensive plan for avoiding your triggers and preventing allergic reactions.

When to seek care

Call your doctor if you have experienced symptoms of a food allergy shortly after eating.

If you are experiencing symptoms of anaphylaxis, seek emergency medical treatment immediately.

Next Steps

Patients will likely need to consult a doctor who specializes in allergies and immunology, to manage long-term symptoms and prevent anaphylaxis.