Food Allergy

Food allergy affects millions of people worldwide and occurs when the body’s immune system mistakenly treats certain foods as harmful invaders, triggering reactions that can range from mild discomfort to life-threatening emergencies.

Table of contents

• What Is Food Allergy?
• How Common Are Food Allergies?
• Most Common Food Allergens
• Signs and Symptoms
• Understanding Anaphylaxis
• What Causes Food Allergies?
• Who Is at Higher Risk?
• How Food Allergies Are Diagnosed
• Treatment and Management
• Living with Food Allergies

What Is Food Allergy?

A food allergy is a condition where your body’s natural defense system, called the immune system, overreacts to certain foods that it mistakenly believes are dangerous.^[1] When you eat a food you’re allergic to, your immune system treats it as if it were a harmful virus or bacteria and sends out chemicals to defend against it.^[2]

This defensive reaction happens when your immune system identifies certain food proteins as harmful invaders and activates protective mechanisms to flush the allergen out of your system.^[8] Even a tiny amount of the allergy-causing food can trigger symptoms.^[1]

Food allergy is different from food intolerance, which is a less serious condition that does not involve the immune system and typically causes symptoms like bloating and stomach pain, usually a few hours after eating the food.^[1][3]

How Common Are Food Allergies?

Food allergies affect millions of people across the United States. An estimated 8% of children under age 5 and up to 4% of adults have food allergies.^[1] More recent data shows that approximately 7.6% of children and 10.8% of adults in the United States have food allergies.^[5]

The condition affects about 33 million Americans in total, including 26 million adults and 5.6 million children.^[5] Food allergy symptoms are most common in babies and children, but they can appear at any age. You can even develop an allergy to foods you have eaten for years with no problems.^[2]

The prevalence of food allergies in children increased by 50% between 1997 and 2011.^[5] Among children under 18, food allergies are common enough that there are about 2 students with food allergies in every classroom.^[5]

Most Common Food Allergens

While any food can cause an allergic reaction, nine types of food account for about 90 percent of all reactions.^[2][6] These foods are:

• Peanuts
• Tree nuts (such as almonds, walnuts, pistachios, hazelnuts, pecans, cashews, and Brazil nuts)
• Milk and dairy products
• Eggs
• Fish (such as halibut and salmon)
• Shellfish (such as crab, lobster, and shrimp)
• Wheat
• Soy
• Sesame

Sesame is the 9th most common food allergen and is found in many popular dishes, including hummus, under the name “tahini.”^[2] According to U.S. regulations, sesame was added as a major food allergen effective January 1, 2023.^[2]

Other foods that can cause allergic reactions include celery, mustard, and sesame seeds, as well as lupin flour found in some baked goods.^[3]

Signs and Symptoms

Food allergy symptoms usually develop within a few minutes to two hours after eating the food that causes the reaction.^[1] In most cases, symptoms occur within two hours of eating, and often they start within minutes.^[2] Rarely, symptoms may be delayed for several hours, or in some very rare cases, by four to six hours or even longer.^[1][2]

Symptoms of a food allergy can affect any part of the body, including different parts at the same time.^[3] They can range from mild to severe, and a food that triggered only mild symptoms on one occasion may cause more severe symptoms at another time.^[2]

Common symptoms include:

• Tingling or itching in the mouth
• Hives, itching, or skin rash
• Swelling of the lips, face, tongue, throat, or other parts of the body
• Difficulty swallowing or a hoarse voice
• Wheezing, shortness of breath, or difficulty breathing
• Coughing or repetitive cough
• Runny nose or sneezing
• Stomach pain or abdominal cramps
• Nausea or vomiting
• Diarrhea
• Dizziness, lightheadedness, or feeling faint

Understanding Anaphylaxis

Anaphylaxis is a serious allergic reaction that comes on quickly and has the potential to become life-threatening.^[5] It is a whole-body allergic reaction that can impair breathing, cause a dramatic drop in blood pressure, and affect heart rate.^[2] Anaphylaxis can come on within minutes of exposure to the trigger food and can be fatal if not treated promptly.^[2]

Life-threatening symptoms of anaphylaxis include:

• Constriction and tightening of the airways
• A swollen throat or the sensation of a lump in your throat that makes it difficult to breathe
• Trouble swallowing
• Shock or circulatory collapse
• Weak pulse
• Pale or blue coloring of skin
• Severe drop in blood pressure
• Loss of consciousness or fainting

If you or someone you’re with is having a serious allergic reaction, call 911 or get to an emergency room immediately.^[3][6] If you have an adrenaline auto-injector (such as an EpiPen), you should use it immediately, even if you or the person seems to be feeling better afterward.^[3]

A second round of allergic reactions, called biphasic anaphylaxis, can occur after the initial reaction. It may happen as early as an hour or up to 72 hours later, with an average of 10 hours. This second reaction can be less severe, as severe, or even more severe than the initial reaction.^[5] Because of this risk, observation in a hospital for 4 to 24 hours is recommended after the individual returns to normal.^[5]

Each year in the United States, severe reactions to food cause approximately 30,000 emergency room visits, 2,000 hospitalizations, and 150 deaths.^[5] Every 10 seconds, a food allergy reaction sends a patient to the emergency room.^[4]

What Causes Food Allergies?

Food allergy is caused by your immune system overreacting to certain types of food.^[3] When you have a food allergy, your immune system mistakenly identifies a food protein as something harmful, as if it were a virus or bacteria.^[8]

The job of the body’s immune system is to identify and destroy germs that make you sick.^[4] In people with food allergies, the immune system overreacts to a food or a substance in a food, identifying it as a danger and triggering a protective response.^[2]

It’s not entirely clear why this happens, but certain foods are more likely to cause an allergic reaction in some people.^[3] When you eat something you’re allergic to, it activates mechanisms meant to protect you and flush the allergen out of your system, which causes your symptoms.^[8]

Who Is at Higher Risk?

You have a slightly higher chance of getting a food allergy if you or a close family member have other allergies, asthma, or eczema.^[3][8]

While allergies tend to run in families, it is impossible to predict whether a child will inherit a parent’s food allergy or whether siblings will have a similar condition.^[2] However, some research does suggest that the younger siblings of a child with a peanut allergy will also be allergic to peanuts.^[2]

The tendency for people to have eczema, asthma, and allergies together is called atopy.^[8] Food allergy is among the diseases considered to be part of the Atopic March, also known as the Allergic March. This term refers to the progression of allergic diseases in a person’s life: eczema, food allergy, allergic rhinitis, and asthma. Not everyone will follow this progression or experience every condition.^[4]

How Food Allergies Are Diagnosed

Healthcare providers diagnose food allergies by asking about your symptoms and performing allergy testing.^[8] There’s no perfect test used to confirm or rule out a food allergy, so your healthcare team will consider several factors before making a diagnosis.^[7]

If a doctor thinks you have a food allergy, you may be referred to a specialist for tests.^[3] Tests you may have include:

Skin-prick test: A small amount of liquid containing a food you may be allergic to is placed on your skin to see if it reacts. If you’re allergic to a particular substance being tested, you develop a raised bump or reaction. However, a positive reaction to this test alone isn’t enough to confirm a food allergy.^[3][7]

Blood test: A blood test can measure your immune system’s response to particular foods by measuring the allergy-related antibody known as immunoglobulin E (IgE). A blood sample taken in your care professional’s office is sent to a medical laboratory and tested for foods that could have caused an allergic reaction.^[7]

Elimination diet: You may be asked to eliminate suspect foods for a week or two and then add the food items back into your diet one at a time. This process can help link symptoms to specific foods. However, elimination diets aren’t foolproof and can’t tell you whether your reaction to a food is a true allergy instead of a food sensitivity.^[7]

Food challenge: This test involves eating small amounts of the suspected food under medical supervision to confirm or rule out an allergy.^[3]

You may also be asked to keep a food and symptoms diary to help work out what may be triggering your symptoms.^[3]

Treatment and Management

There is no cure for food allergies.^[15] The primary preventive therapy against a recurrent food allergy is strict elimination of the offending food allergen from the diet and avoidance of any contact with the food by ingestion, skin contact, inhalation, or injection.^[11] Avoidance of the food allergen is the only way to protect against a food allergy reaction.^[15]

While there’s no cure, some children outgrow their food allergies as they get older.^[1] There are now FDA-approved treatment options available.^[5] Children with a peanut allergy may have immunotherapy to help their bodies become less sensitive to peanuts, but they should still avoid eating peanuts.^[3]

Emergency Medications

Epinephrine (adrenaline) is the drug of choice for the initial management of a food-induced anaphylactic reaction.^[11] Injectable epinephrine is the only medication that can reverse the symptoms of anaphylaxis.^[5] If you have a food allergy, your doctor will likely prescribe an epinephrine auto-injector and provide you with instructions on how to use it.^[15]

Ensure that you have self-injectable epinephrine readily available at all times.^[11] Prompt administration of epinephrine is crucial to surviving a potentially life-threatening reaction. Epinephrine has very few side effects and is available as an auto-injector device (such as Auvi-Q or EpiPen) or nasal spray (neffy).^[5]

If you or someone you know is at risk of anaphylaxis, carry two epinephrine auto-injectable devices.^[5] Always carry your epinephrine auto-injector or have immediate access to it, and be sure to replace all devices when they have expired.^[15]

Advanced medical therapy for food allergen-induced anaphylaxis may include antihistamines, bronchodilators, corticosteroids, and administration of intravenous fluids, glucagon, and oxygen. In severe anaphylaxis, ventilatory and circulatory support may be needed.^[11]

Managing Your Allergy

If you have a food allergy, you will not be able to eat the food you’re allergic to, including foods where you’re allergic to any of the ingredients.^[3] Your specialist will give you an allergy management plan that will explain how to manage your allergy.^[3]

Ask your doctor to provide a written food allergy action plan, outlining the treatment course you should follow in the event of an allergic reaction. Make sure school staff and all caregivers have a copy of this plan.^[15] To help communicate your food allergy to others during an emergency, wear medical identification jewelry.^[15]

Living with Food Allergies

Managing a food allergy daily involves constant vigilance. Even trace amounts of an allergen can trigger an allergic reaction in some individuals.^[5] However, with proper preparation and awareness, you can live a normal life with food allergies.

Reading Food Labels

Always read food labels thoroughly, and at least twice, even if it is an item you wouldn’t think would contain your food allergen.^[15] In the United States, food manufacturers must state on their labels if foods contain any of the most common allergens: peanuts, tree nuts, shellfish, fish, wheat, milk, sesame, eggs, and soy.^[18]

If a food does not have an ingredient label, it is safest to avoid that food.^[15] Check packaging thoroughly—sometimes an ingredient listing is placed on one side of a product and an advisory label (such as “may contain”) is placed on another side.^[15] Avoid products with advisory labels for your specific allergen, as such labeling communicates some level of risk.^[15]

Read ingredient statements for non-food products, such as lotions, soaps, hair care products, and medications, to ensure these items do not contain an ingredient to which you are allergic.^[15]

Preparing Food Safely

If everyone in the household isn’t following an allergen-free diet, you want to be sure to avoid cross-contamination.^[14] Cross-contamination happens when a food you are not allergic to comes in contact with a food you are allergic to.^[18]

It’s a good idea to have two sets of cooking and eating utensils—one exclusively for the allergic person—so that a knife used to cut a peanut butter sandwich isn’t inadvertently pressed into service buttering the toast of someone who’s allergic to peanuts.^[14] All dishes and utensils should be thoroughly washed in hot, soapy water between uses.^[14]

Meal preparation must consider avoidance of cross-contact through shared utensils or fryers of allergens with otherwise safe foods.^[11]

Eating Out and Traveling

It’s wise to let the restaurant’s manager or chef know about your food allergy before you order.^[14] Speak to a restaurant’s manager and chef about the accommodations you need before dining out. Order food that is simply prepared, and avoid desserts, as they often contain or have come into contact with food allergens.^[15]

People with food allergies often carry a chef card—a printed note specifying all the ingredients you are allergic to as well as a request that all dishes, utensils, and preparation surfaces be free from traces of that food.^[14]

Before traveling, plan for how food allergies will be managed. For example: Will you pack your own food for the trip? Will you have food shipped to your destination? Will you need additional medication? Make sure you keep emergency medication in your carry-on luggage if you are flying.^[15]

Teaching Children About Food Allergies

If your child has food allergies, teach them which foods they must avoid and what these foods look like. Role-play with your child so that he or she understands how to respond if a well-meaning person offers food or drink.^[15]

Work with caregivers and school staff to ensure they know about your child’s allergy. Their school or daycare should have an epinephrine auto-injector and any other medications they might need on hand, along with an allergy action plan from your child’s healthcare provider on file.^[16]

Finding Support

There are more resources than ever for people living with food allergies. Online communities can help you find go-to restaurants and groceries and provide other helpful information. You can also ask your healthcare provider for recommendations.^[16]