What Is a Food Allergy?

A food allergy occurs when the immune system reacts abnormally to proteins in certain foods. Even tiny amounts of the allergenic food can trigger symptoms, usually within minutes but sometimes after a few hours. Food allergies can start in childhood or adulthood, sometimes appearing suddenly after eating a food that previously caused no issues. Some food allergies in young children may resolve over time.

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Common Foods That Cause Allergies

The most frequent allergens include:

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

Symptoms of Food Allergies

Food allergy symptoms range from mild discomfort to severe, life-threatening reactions. If any allergic reaction occurs, it’s important to see an allergist to identify the cause.

Mild to Moderate Symptoms

  • Itchy or flushed skin
  • Hives
  • Vomiting, stomach pain, diarrhea
  • Sneezing, runny nose, congestion
  • Itchy or watery eyes
  • Swelling beneath the skin (angioedema)

Severe Symptoms

  • Throat swelling and hoarseness
  • Difficulty breathing, wheezing, chest tightness
  • Dizziness or loss of consciousness
  • Anaphylactic shock

If anaphylaxis occurs, seek emergency medical help immediately, as delayed treatment can be fatal.

Causes of Food Allergies

Food allergies happen when the immune system mistakenly identifies a food protein as harmful. This causes the body to produce antibodies that, upon subsequent exposure, trigger the release of histamines and other chemicals. These chemicals cause the allergy symptoms.

Risk Factors

Certain individuals, especially children, are more prone to food allergies. Risk factors include:

  • Having other allergic conditions like eczema or asthma
  • Personal history of food allergies, even if symptoms have gone away
  • Family history of food allergies or other allergic diseases

Diagnosing Food Allergies

Many people confuse food intolerance (such as lactose intolerance) with food allergies. Unlike allergies, intolerances often allow small amounts of the food without symptoms. Accurate diagnosis is critical to avoid unnecessary food restrictions or dangerous exposures.

An allergist diagnoses food allergies by:

  • Taking a detailed medical history
  • Conducting skin prick tests and blood tests
  • Occasionally performing supervised “food challenges” to confirm the diagnosis

Treatment of Food Allergies

The best way to manage a food allergy is strict avoidance of the offending food. This includes carefully reading ingredient labels and asking about food preparation in restaurants or other homes.

  • For mild reactions, antihistamines can help relieve symptoms.
  • For severe reactions, immediate medical care is necessary. Individuals with serious allergies should carry prescribed injectable epinephrine at all times.