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Understanding Food Allergy Symptoms: Tips for Testing and Management

Written by Andrew Le, MD

UpdatedMay 29, 2024

Over 100 million people in the US experience various types of allergies yearly, ranking as the country's sixth leading cause of chronic illness. Although food is essential for nourishment and sustenance, certain foods can trigger allergic reactions in some individuals.

A food allergy arises when the body's immune system overreacts to specific proteins found in certain foods, leading to a wide range of symptoms that can vary in severity. Among the most severe reactions is anaphylaxis, a potentially life-threatening response that can develop rapidly and affect multiple systems in the body.

In this article, you will learn everything you need about food allergies – from common symptoms and causes to the diagnostic tests and treatments available.

Whether you suspect you have a food allergy or want to learn more about this important health topic, read on to become well-informed about food allergies and how to manage them effectively!

Understanding Food Allergies

A food allergy is an immune response to certain proteins in particular foods. When the body comes into contact with these proteins, it mistakenly identifies them as harmful invaders, triggering an allergic reaction. Food allergies can affect people of all ages, and the symptoms can vary widely from person to person.

Let's explore this topic in more detail, from common allergic foods to the causes of food allergies.

Common Symptoms of Food Allergies

Food allergy symptoms can manifest in various body parts. They may occur immediately after eating the trigger food or appear after a few hours or even days later.

Some common symptoms include:

  • Feeling Dizzy or Lightheaded: Individuals with food allergies may experience dizziness or lightheadedness.
  • Itchy Skin or Hives: Allergic reactions can cause the skin to become itchy, leading to raised rash-like hives.
  • Swelling of Lips, Face, and Eyes: Swelling facial features, such as lips, face, and eyes, is a common symptom of food allergies.
  • Respiratory Issues: Food allergies can affect the respiratory system, leading to symptoms like coughing, wheezing, breathlessness, noisy breathing, or a hoarse voice.
  • Nasal Symptoms: Sneezing or an itchy, runny, or blocked nose may occur in response to a food allergen.
  • Digestive Problems: Gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and diarrhea are common in food allergies.

Did You Know?

According to the CDC, approximately 8% of children in the US are affected by food allergies. While food allergy symptoms are most prevalent in babies and children, they can develop at any stage of life. Dr. Daryl Gioffre, a nutritionist and expert in gut health, explains the indications of a food allergy and the available treatment options. You can watch the discussion here: CBS News: How to tell if you have a food allergy, according to a nutritionist

Common Food Allergies

While any food can potentially trigger an allergic reaction, certain foods are more commonly associated with food allergies. Some of the most prevalent allergenic foods include:

  • Cow’s Milk Milk: Cow's milk allergy is common, especially in infants and young children.
  • Eggs: Allergic reactions to eggs are frequent, but many children eventually outgrow this allergy.
  • Peanuts: Peanut allergies are often lifelong and can cause severe reactions.
  • Tree Nuts: Tree nuts, such as almonds, walnuts, and cashews, can cause severe allergic reactions.
  • Shellfish: Crustaceans like prawns, crabs, and lobsters are known allergens.
  • Wheat: A wheat allergy can lead to various symptoms, and people with wheat sensitivity may have to avoid gluten-containing products.

It's essential to note that people can be allergic to other less common foods, including celery, mustard, sesame seeds, and lupin flour found in some baked goods.

Causes of Food Allergies

The exact cause of food allergies is not fully understood. Still, it is believed to result from an overreaction of the immune system to specific food proteins.

Some individuals may be more genetically predisposed to develop food allergies, and there is evidence that having other allergies, asthma, or eczema can increase the risk of food allergies.

Tests for Food Allergies

Suppose you suspect that you or someone you know has a food allergy. In that case, seeking medical evaluation for proper diagnosis and management is crucial. Medical professionals may conduct various tests to determine the presence and severity of a food allergy.

Here are the essential tests for food allergy that can help determine the presence and severity of the condition:

1. Skin-Prick Test

The Skin-Prick Test is a common diagnostic method used to identify food allergies. In this test, a small amount of liquid containing the suspected food allergen is applied to the skin, typically on the forearm or back. Then, the skin is pricked with a sterile probe to allow the allergen to penetrate the skin slightly.

A small raised bump or wheal will appear at the test site if the person is allergic to the food. The size of the wheal may indicate the severity of the allergy.

2. Blood Tests

Blood tests, such as measuring specific IgE antibodies, are also valuable tools for identifying food allergies. These tests assess the presence of allergen-specific antibodies in the blood, which indicate a potential allergic reaction to certain foods.

Blood tests can be beneficial when skin tests are inconclusive or when there is a concern about skin test reliability due to underlying skin conditions. They can provide additional insights into food allergies and complement the diagnostic process.

3. Elimination Diet

Sometimes, healthcare providers recommend an Elimination Diet to help identify trigger foods. This process involves avoiding suspected allergenic foods for a specific period and reintroducing them one at a time.

The goal is to observe allergic reactions and pinpoint the specific food allergens causing the symptoms. Keeping a daily food diary during the Elimination Diet can help track food intake and related symptoms, aiding in the diagnostic process.

4. Oral Food Challenge

The Oral Food Challenge is the most definitive test for diagnosing food allergies. Under medical supervision, the patient is given increasing amounts of the suspected food to monitor for adverse reactions.

This test is particularly valuable when other tests yield uncertain results or when there is a need for a conclusive diagnosis. However, an Oral Food Challenge must be conducted in a controlled environment with access to emergency medical care, as it can potentially trigger severe allergic reactions.


It's essential to remember that qualified healthcare professionals, such as allergists or immunologists, should perform food allergy testing to ensure accurate results and safe evaluation.

Treatments for Food Allergies

The primary treatment for food allergies is avoidance of the trigger foods. If a food allergy is diagnosed, the individual must eliminate the trigger food from their diet.

Additionally, there are specific treatments available to manage allergic reactions. Here are several common treatments:

1. Antihistamines

Antihistamines often relieve mild allergic reactions, such as itching, hives, and sneezing. They work by blocking the effects of histamine, a chemical released during an allergic response.

2. Epinephrine Auto-Injectors

For severe allergic reactions or anaphylaxis, epinephrine auto-injectors are essential. These devices deliver a dose of epinephrine (adrenaline) to quickly reverse life-threatening symptoms and buy time for emergency medical assistance.

3. Allergy Management Plan

Individuals with food allergies should work with their healthcare providers to develop a personalized allergy management plan. This plan outlines how to avoid allergenic foods, recognize symptoms of allergic reactions, and manage emergencies.

4. Immunotherapy

Sometimes, allergists may recommend immunotherapy, especially for children with peanut allergies. This treatment involves gradual exposure to small amounts of the allergen under medical supervision to desensitize the immune system.


Anaphylaxis is a severe and potentially life-threatening allergic reaction that can occur rapidly after exposure to allergens such as food, latex, insect stings, and medicines. It involves many signs and symptoms that can manifest alone or in combination. The condition demands immediate medical attention and administration of epinephrine.

Anaphylaxis can develop rapidly, with symptoms often emerging within minutes and usually within 30 minutes of allergen exposure. However, in some cases, it may take up to 2 hours for symptoms to appear, especially after exposure to specific food allergens. This swift onset makes recognizing the signs of anaphylaxis crucial for timely intervention.

Symptoms of Anaphylaxis

The symptoms of anaphylaxis can vary widely. They may include:

  • Skin Reactions: Itching, hives, and swelling are common skin manifestations of an allergic reaction.
  • Respiratory Distress: Difficulty breathing, wheezing, and chest tightness may occur due to airway constriction.
  • Gastrointestinal Distress: Nausea, vomiting, abdominal cramping, and diarrhea can indicate anaphylaxis.
  • Reduced Blood Pressure: This is a critical sign of anaphylaxis and may lead to weakness, confusion, or even loss of consciousness.

Biphasic Anaphylaxis

In some cases, a second round of allergic reactions, known as "biphasic anaphylaxis," can occur after the initial response. The second reaction may happen as early as an hour after the first reaction or 72 hours later, with the average time being 10 hours later.

Importantly, this second phase can be less severe, as severe, or even more severe than the initial reaction. Due to the unpredictability of biphasic anaphylaxis, individuals will often be observed in the emergency department for a variable period of time or even admitted to the hospital for observation after their symptoms have resolved. However, there isn’t a consensus on the duration of observation for post-anaphylactic monitoring, as it may vary depending on individual cases and medical practices.

Coping with Food Allergies

If you have a food allergy, taking specific precautions to manage your condition effectively is essential. Here are some practical steps you can take:


  • Carefully read food labels to identify potential allergens in packaged foods.
  • Inform family, friends, school, and the workplace about your food allergy.
  • Always carry at least two epinephrine auto-injectors if prescribed by your healthcare provider.
  • Communicate your food allergy to restaurant staff and airlines before dining or traveling.
  • Wipe down surfaces in public places before eating to avoid cross-contamination.


  • Underestimate the seriousness of your food allergy; even a small amount of allergenic food can trigger a severe reaction.
  • Hesitate to seek medical attention in case of an allergic reaction.
  • Forget to inform caregivers or teachers about your child's food allergies, especially in schools or daycare centers.

Tips for Parents of Children with Food Allergies

If you are a parent or caregiver of a child with food allergies, here are some additional tips to ensure their safety and well-being:

Education and Communication

Educate your child about their food allergy in an age-appropriate manner. Teach them to recognize allergens, inform adults about their allergies, and never share food with others.

Safe Food Alternatives

Find suitable food alternatives free from allergens and provide balanced nutrition for your child. Seek guidance from a registered dietitian if needed.

Allergy-Proof the Home

Keep allergenic foods out of reach and ensure proper labeling of foods in the refrigerator and pantry. Clean kitchen surfaces regularly to avoid cross-contamination.

Prepare for Emergencies

Have an allergy action plan, and ensure all caregivers, teachers, and family members are familiar. Teach them how to use an epinephrine auto-injector if necessary.

Inclusive Activities

Work with your child's school or extracurricular activities to create an inclusive environment. Encourage allergy-friendly events and ensure staff members are trained to handle allergic reactions.

Food Allergy vs. Food Intolerance

Food allergies and food intolerances are two distinct conditions that can affect how our bodies react to certain foods. While they share some similarities in symptoms, their underlying causes and severity differ.

Food Allergy:

  • Involves the immune system.
  • Triggers an immediate reaction.
  • Even small amounts of allergenic food can cause a severe response.
  • Involves symptoms such as hives, swelling, respiratory distress, and in severe cases, anaphylaxis.

Food Intolerance:

  • Does not involve the immune system.
  • The reaction may be delayed and gradual.
  • Typically occurs with large quantities of the offending food.
  • Involves symptoms like bloating, gas, and stomach cramps.

The interesting thing about food intolerance is that some people can still eat small amounts of the problem food without getting severe symptoms.

For example, those with lactose intolerance might find relief by choosing lactose-free milk or taking lactase enzyme pills to help digestion. This flexibility allows individuals to adapt their diet and manage their food intolerances better.


Everyone's body is unique, and what works for one person may not work for another. Prioritize your health, listen to your body, and consult healthcare professionals for tailored guidance and support.

Wrap Up

Food allergies can significantly impact an individual's quality of life. Still, with proper management and precautions, it is possible to lead a fulfilling life.

If you suspect a food allergy or have been diagnosed, work closely with your healthcare provider to create an allergy management plan. Always carry any prescribed medication, such as an epinephrine auto-injector, and be vigilant about reading food labels and communicating your allergy to others.

Early detection, accurate diagnosis, and timely treatment are essential to effectively managing food allergies and preventing severe reactions. By staying informed and taking necessary precautions, you can safely navigate life with a food allergy and enjoy a healthy lifestyle.

FAQS on Food Allergy:

Why be aware of food allergies?

Food allergies can be life-threatening. While most symptoms are mild, some may progress to severe allergic reactions like anaphylaxis, leading to constricted lung airways.

Are food allergies genetic?

Food allergies may have a genetic component, but they can also be influenced by genetic predisposition and environmental factors. Allergies within families might reflect shared environmental conditions contributing to their development.