Food allergy - Symptoms and causes

Understanding Food Allergies

Food allergies are more than just a minor annoyance. For millions of people—especially kids—they can cause symptoms ranging from mild discomfort to life-threatening reactions. Understanding food allergy symptoms and what causes them is the first step to safe and effective management.

At Empower Allergy Treatment, we help individuals and families in San Diego take control of their food allergies through early diagnosis, education and advanced treatment options. If you or your child have ever had a reaction to something you ate, this guide will help you understand what’s happening in your body—and what to do next.

What Is a Food Allergy?

A food allergy occurs when the body mistakes a harmless food protein for a threat. This triggers an immune response, releasing histamine and causing symptoms throughout the body.

It’s important to distinguish between a food allergy and food intolerance. While intolerances (like lactose intolerance) affect digestion and can be uncomfortable, food allergies involve the immune system and can be serious, even life-threatening.

Some reactions happen immediately, within seconds to minutes of eating. Others are delayed, hours later. A related condition, oral allergy syndrome, causes mild reactions (like itchy mouth or throat) to certain fruits or vegetables due to cross-reactivity with pollen.

The Top 9 Food Allergens

The FDA lists nine foods that account for most of the allergic reactions. These are:

• Milk
• Eggs
• Peanuts
• Tree nuts (like walnuts, almonds, cashews)
• Wheat
• Soy
• Fish
• Shellfish
• Sesame

Each of these allergens can cause different symptoms in different people. For example, milk allergies in kids often cause vomiting or hives, while shellfish allergies in adults may cause swelling or breathing difficulties.

You can be allergic to more than one food and reactions can vary in severity over time.

Food Allergy Symptoms: Mild to Severe

Mild Symptoms

These are the first warning signs of a food allergy:

• Itchy skin or hives (urticaria)
• Mild swelling of the lips, face or eyes
• Nasal congestion or sneezing
• Nausea or mild stomach cramps

These symptoms may go away on their own but repeated exposure can lead to more serious reactions.

Moderate to Severe Symptoms

• Vomiting or diarrhea
• Wheezing or coughing
• Swelling of the tongue or throat
• Trouble swallowing
• Chest tightness or rapid heartbeat

These symptoms indicate a more significant immune response and may require medical treatment.

Anaphylaxis

The most serious type of food allergy reaction is anaphylaxis. Symptoms include:

• Difficulty breathing
• Drop in blood pressure
• Dizziness or fainting
• Loss of consciousness

Anaphylaxis is a medical emergency. It requires immediate treatment with epinephrine and a call to 911.

If you’ve had any of the above, ask about our Services and Programs to create a personalized allergy management plan.

What Causes Food Allergies?

Food allergies are often thought to be genetic but the causes are more complex. Key contributors are:

• Genetics: A family history of food allergies, asthma or eczema increases risk.
• Immune system development: Children with altered gut microbiomes or underdeveloped immune regulation may develop allergies more easily.
• Environmental factors: Early life exposures—like antibiotics, pollution or delivery by C-section—may influence allergy risk.
• Early introduction of allergenic foods: Delayed exposure to certain foods may increase the chance of developing an allergy.

In short, food allergies happen when the body mistakes proteins in food as dangerous, triggering a defense that causes the symptoms we recognize as an allergic reaction.

Who’s at Risk for Food Allergies?

Infants and Children

Food allergies develop in infancy or early childhood. In fact, up to 8% of U.S. children have at least one diagnosed food allergy.

Risk factors are:

• Family history of allergies or asthma
• Eczema or other atopic conditions
• Delayed introduction of allergenic foods
• Antibiotic use or gut dysbiosis

Teens and Adults

Though less common, food allergies can start in adolescence or adulthood. Shellfish, tree nuts and sesame are among the top adult-onset allergens.

We diagnose food allergies in patients of all ages, whether symptoms began early in life or developed recently.

How Food Allergies Are Diagnosed

Diagnosing a food allergy is a multi-step process. At Empower Allergy Treatment, we start with a full health history and then recommend testing based on your symptoms.

Skin Prick Testing - A small amount of food protein is placed on the skin and the skin is gently pricked to see if there’s a reaction.

Blood Testing - This measures IgE antibodies in the blood to specific food allergens.

Oral Food Challenge - Considered the gold standard, this test involves eating small amounts of the suspected allergen under medical supervision to see if there’s a reaction.

Lung Function Testing - For patients with asthma or breathing symptoms, this may be used to assess airway response and overall respiratory health.

Each test helps us understand your body’s unique response and develop a safe and effective treatment plan.

When to See a Specialist

If you or your child has any of the following, it’s time to see an allergist:

• Recurring hives or skin reactions after eating
• Stomach pain or vomiting after eating
• Trouble breathing, coughing or wheezing during meals
• A known allergy but no treatment plan in place
• Fear or anxiety around eating new foods

Empower Allergy Treatment offers compassionate, evidence-based care for children, teens and adults. Learn more about our providers and mission on our About Us page.

Treatment Options for Food Allergies

While avoiding allergens is important, advances in allergy treatment are giving patients new ways to build tolerance and reduce reaction severity.

Oral Immunotherapy (OIT) -This involves gradually introducing tiny amounts of the allergen over time to desensitize. OIT has helped thousands reduce the risk of severe reactions and have more freedom in daily life.

Sublingual Immunotherapy (SLIT)- An alternative to OIT, SLIT delivers allergen drops under the tongue. It’s used for environmental and some food allergies with fewer side effects.

Xolair (omalizumab) -Originally developed for asthma, Xolair is now FDA-approved to be used with oral immunotherapy for food allergies. It reduces allergic inflammation and makes desensitization safer.

Avoidance Planning - For patients with severe allergies, we create detailed avoidance plans, emergency action plans and guidance for travel, school and eating out.Your treatment plan is tailored to your lifestyle, preferences and medical history—because no two allergies are the same.

Conclusion: Early Awareness = Empowered Life

Knowing the symptoms of food allergies and what causes them is key to your health and well-being. Whether you’re new to a diagnosis or looking for better control of existing allergies, you deserve expert care and personalized support.

At Empower Allergy Treatment, we believe in giving families the tools and confidence to live their best lives. From initial testing to advanced treatments like OIT, SLIT and Xolair, we’re here for you every step of the way.

Get Started Today

Don’t wait until symptoms get worse. If you suspect a food allergy, book an appointment with our team to get the answers and peace of mind you need