What is a food allergy?

Food allergies occur when the body’s immune system overreacts to something you eat. The body could think the food or ingredient is a danger and trigger a defensive response.

Fifty million people in the United States suffer from some kind of food allergy. The Centers for Disease Control and Prevention estimates that 4 to 6 percent of children and 4 percent of adults have a food allergy.

Allergies to eggs, milk, peanuts, tree nuts, fish, shellfish, wheat and soy cause 90 percent of all food related reactions.

Common related conditions
Eczema (Atopic Dermatitis) Contact Dermatitis (Skin Reactions) Drug Allergy

Causes of a food allergy

Food allergies are caused by a specific food or ingredient in the food that you have eaten.

Any food can cause an allergic reaction, but milk, egg, peanuts, tree nuts, fish, shellfish, wheat, soy are the most common causes in children. In teens, peanuts, tree nuts, fish and shellfish are the most common causes.

If you have the allergy as a child, you most likely will have it for life.

Risk factors for a food allergy

  • Family history of food allergies – food allergies can run in families
  • Younger age – younger children are more likely to have food allergies than adults
  • Presence of another allergic condition such as asthma or atopic dermatitis
  • Medical condition where allergens can pass into the bloodstream

Symptoms of a food allergy

Symptoms can be mild or severe and typically occur within two hours of ingestion. Some patients will experience symptoms within minutes.

Symptoms of food allergies include:

  • Vomiting
  • Hives
  • Shortness of breath
  • Repetitive cough
  • Weak pulse
  • Pale or blue coloring of skin
  • Dizziness or feeling faint
  • Anaphylaxis

Diagnosis of a food allergy

Diagnosing food allergies is challenging. Symptoms often differ from person to person and from attack to attack. Symptoms of food allergies can mimic symptoms for other conditions, and they can occur at any age.

When a food allergy is suspected, your primary care doctor will refer you to an allergist. The allergist can determine which food allergy tests to perform.

Patients should keep a food log before visiting the allergist. During the physical exam, you will be asked detailed questions about your symptoms.

Be prepared to answer the following questions:

  • What foods did you consume?
  • What quantity of food did you consume?
  • How long did the symptoms take to develop?
  • What are your symptoms?
  • How long did the symptoms last?

Your allergist may order a blood test as well as perform a skin prick food allergy test. These tests can show if food-specific IgE antibodies are present in the body.

Although positive tests can confirm the presence of a food allergy, how your body will respond is sometimes a mystery. Some people will never react to the specific food he or she is allergic to, and others may have severe reactions. On the other hand, a negative test will rule out a food allergy to specific foods.

Treatment for a food allergy

The best way to avoid food-related allergic reactions is to avoid the food causing the reaction. Some allergies fade over time, but allergies to peanuts, tree nuts, fish and shellfish typically last for life.

Because the symptoms of a reaction can be life-threatening, it is important for patients who have severe food allergies to carry an epinephrine (commonly known as EpiPen) auto-injector at all times. If you or your child has a serious reaction, use the EpiPen immediately.

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