Food Allergies

What Are Food Allergies?

Food allergies are an immune-system reaction. When the immune system is not working right, it thinks a harmless food protein is a dangerous invader. To protect the body from that food, the immune system produces the immunoglobulin E (IgE) antibody. IgE triggers cells to release substances that cause allergic reaction symptoms.

Food allergies in children and adults are common. About 33 million (Opens in a new window) people have food allergies, that’s about 1 in 13 children and 1 in 10 adults. Globally, food allergies affect 220 million people (Opens in a new window) (Opens in a new window) (Opens in a new window) (Opens in a new window). 

Rates of Food Allergy by Country (Opens in a new window)

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Most food allergies develop in babies, but it is possible to develop food allergies later in life. Allergies to some foods, such as milk, egg, wheat and soy are commonly outgrown if they start during childhood. Others like peanuts or tree nuts are usually lifelong allergies.

Food Allergy Causes

According to the Food and Drug Administration (Opens in a new window) (Opens in a new window) (Opens in a new window) (Opens in a new window), more than 160 foods can cause food allergies in people who are food sensitive. 

9 Most Common Food Allergens

1. Dairy
2. Egg
3. Fish (such as bass, cod flounder)
4. Peanuts
5. Shellfish (clams, crab, lobster, shrimp and scallops)
6. Tree nuts (almond, Brazil nut, cashew, hazelnut, macadamia, pecan, pine nut, pistachio walnut)
7. Wheat
8. Sesame 
9. Soybeans

These allergens account for 90% of food allergies and serious reactions. 

Signs and Symptoms

Food allergies signs and symptoms can vary from person to person. An allergic reaction to food typically starts within minutes to a few hours of eating. 

Common Symptoms 

• Coughing, wheezing or trouble breathing
• Hives
• Itching or tingling in the mouth, face tongue or lips
• Runny nose, sneezing or congestion
• Stomach pain, nausea or vomiting
• Swelling of the lips, face, tongue or throat

Less Common Symptoms

• Dizziness, lightheadedness or fainting
• Flushing
• Low blood pressure
• Shock
• Swelling in other parts of the body

Severe food allergy reactions can affect the whole body and be life-threatening. A life-threatening reaction is called anaphylaxis. It can cause loss of consciousness and stopped breathing. Call 911 immediately if you suspect this serious reaction.

Risks for Developing Food Allergies

Food allergies can be inherited. You have an increased risk of developing food allergies if someone in your family has:

• Allergies (hay fever)
• Asthma
• Eczema
• Hives

If you have an allergy to one food, you may be at risk for developing other food allergies. 

Conditions Related to Food Allergies

There are other conditions that mimic food allergies or that are made worse by eating specific foods. The two most common conditions that are often confused with food allergies are food intolerance and oral allergy syndrome.

Food Intolerance 

Food intolerance is different from a food allergy because it is not caused by the immune system. It is the digestive system that can't break down certain foods and causes the problem. A food intolerance is not life-threatening. Learn more about the difference between food allergy and food intolerance. 

Oral Allergy Syndrome

Oral allergy syndrome (OAS), which is also called pollen-food allergy syndrome, affects a small group of people. If you have pollen allergies and notice that eating certain raw fruits and vegetables can cause a food allergy-like reaction, you may have OAS. This reaction happens because some foods have proteins that are similar to pollen proteins. The raw form of those foods can cause symptoms like itching and swelling of the mouth, lip, tongue and throat. OAS reactions can be mild to severe. Learn more about OAS. 

Diagnosis

Food allergies need to be diagnosed by a doctor who specializes in allergy and immunology. 

To diagnose food allergies, the allergist will review your medical history and do a physical exam. The doctor will ask questions about food-related reactions, such as:  

• What food seems to cause symptoms?
• How much of the food did you eat?
• What symptoms did you have after eating the food?
• How long after eating did you have symptoms of an allergic reaction?
• Do you have symptoms every time you eat the food?
• Did you have symptoms when eating other foods?
• Do you have family members who have food allergies?
• What foods are your family members allergic to?

Tests 

Initial testing for food allergies can include allergy skin testing and bloodwork.

Food Allergy Skin Testing

This is a skin prick test. During the test, a small amount of the food allergen is placed on the skin (usually on the back). Then the skin is pricked. If a bump and redness develop where the skin was pricked, that means there is an allergy.  

Food Allergy Blood Test

This simple blood test measures the amount of immunoglobulin E (IgE), the allergy-related antibody, in the blood. This determines if your  immune system will react to certain foods. 

Diagnostic Procedures

Oral Food Challenge

The most accurate test for diagnosing food allergies is the oral food challenge. This medical procedure was developed in the 1970s by  Charles May, MD (Opens in a new window) (Opens in a new window) (Opens in a new window) (Opens in a new window), and his colleagues. Dr. May was a National Jewish Health pediatrician and expert on childhood nutritional disorders. The oral food challenge remains the gold standard way to diagnose food allergies.

During this test, very small amounts of a food is eaten slowly, in gradually increasing amounts.  Food challenges are done under medical supervision and are considered very safe. There is some risk of a severe allergic reaction. Because of that risk, food challenges should only be performed in a medical setting that can handle serious allergic reactions 

Benefits of Food Challenge Testing

• Identify Safe Foods and Foods to Avoid — The  oral food challenge can determine what foods can be eaten safely and identify what foods need to be avoided. It's important to not eliminate the wrong foods from your diet. You can prevent future reactions by knowing the exact food(s) you are allergic to.
• Determine If You've Outgrown a Food Allergy — An oral food challenge can show if you have outgrown a food allergy. Many children who are born allergic to milk, egg, wheat or soy outgrow these allergies. Roughly 1 in 4 children will outgrow a peanut allergy, while 1 in 10 may outgrow a tree nut allergy. A carefully performed food challenge can safely document when the food can be returned to the diet. Food allergies that develop in adulthood are usually lifelong.

Treatment

There is currently no cure for food allergy. However, food allergies are easily treated with self-management that is focused on  preventing and treating allergic reactions.

Preventing Allergic Reactions

To prevent having a food allergy reaction, you need to avoid foods that you are allergic to. You can accidentally eat food allergens when you don't know they are in certain foods. To reduce the risk of accidentally eating a food and having an allergic reaction, you need to:

• Ask about the ingredients in food served outside your home. Know the foods you are allergic to and avoid them.
• Do not eat food when you don't know what's in it.
• Inform and educate people at work, school and home about your food allergy. 
• Know the different names of foods that you are allergic to. For example, casein and whey are both cow's milk products. 
• Know the foods that you are allergic to and avoid them.
• Read labels always because manufacturers can change ingredients at any time.

Learn more about food allergies and how to avoid foods that you are allergic to by talking with your doctor. Another reliable resource is the Food Allergy Research & Education (FARE) (Opens in a new window) organization. 

Treating Allergic Reactions

Accidental exposure to foods happen. Even when you are careful to avoid allergens. Always be prepared to act quickly to treat a food allergy reaction.  

• Carry an epinephrine auto-injector (like EpiPen®) with you always. This is the first line and only treatment for anaphylaxis.
• Keep an oral antihistamine (like cetirizine or Zyrtec®), preferably in liquid or fast-melt forms with you at all times as prescribed for emergencies. Antihistamines can treat mild food allergy reaction symptoms like hives. They do NOT prevent anaphylaxis.
• Know how to recognize an allergic reaction
• Understand your allergy medications and know when and how to use them.

Your doctor may provide a Food Allergy & Anaphylaxis Emergency Action Plan (Opens in a new window). This plan describes how to treat different types of reactions. Follow your treatment plan.

Immunotherapy

Prevention is the main food allergy treatment and the preferred option for most adults and children. In addition, there are treatments available that retrain the immune system. This type of treatment is called immunotherapy. Two of the most common immunotherapy treatments for food allergies are injections and oral immunotherapy. Immunotherapy can reduce your risk of severe food allergy reactions. 

Oral Immunotherapy with PALFORZIA®

Oral immunotherapy (OIT) desensitizes you to a food allergen. It retrains your immune system to tolerate the food instead of seeing it as dangerous. This reduces the risk of reacting to accidental food allergen exposure. With OIT, you eat a very small amount of the food allergen at home every day. Every few weeks you will see your allergist to increase the amount eaten until you reach the maintenance dose. This will increase the amount of allergen it takes to trigger a reaction. Once you reach the maintenance level, having an allergic reaction is less likely and it will be less severe that before the treatment, if one occurs.   

PALFORZIA is made from peanuts. It was approved by the FDA in 2020 to treat peanut allergy in kids ages 1 to 17 years old. The peanut dust or flour comes in capsules. These are opened and mixed into food (like pudding or yogurt) and eaten every day at home. It takes about six months to reach the maintenance dose. You must continue to take the medicine every day to maintain desensitization. You also must follow a peanut-free diet while taking this medicine.

Most patients had only mild allergic symptoms after six months of treatment. Side effects like nausea or vomiting are possible. There is a risk of an allergic reaction, including anaphylaxis because you are eating a food allergen. Read more about the research on the FDA website (Opens in a new window). 

Xolair® Injections

In February 2024, the FDA (Opens in a new window) approved Xolair (omalizumab) injection as a treatment for food allergy in adults and children 1 year and older. Xolair is a prefilled injection that is given in a health care setting and then at home if approved by your doctor. It reduces allergic reactions (including anaphylaxis)  by blocking the allergic reaction process. You must still avoid the foods you are allergic to during this treatment.  

Lifestyle Management

You can manage food allergies successfully with lifestyle habits that include reading food labels and washing hands and surfaces before preparing food. It is also important to educate family, friends, schools and others about your food allergies. Learn more about living with food allergies. 

Clinical Trials

Clinical trials help determine new treatment options for diseases and conditions Patients with food allergies have access to clinical trials and should speak with their doctor to learn what trial may work best for them.

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See a Specialist

It’s important to be evaluated by an allergist if you, your child or a loved one:

• Have had any type of reaction to eating a food or symptoms of a food allergy
• Have been avoiding multiple foods
• Want to determine if you have outgrown a previously diagnosed food allergy
• Need to learn strategies that help prevent food allergies from developing in your baby  
• Want information about treatment options

At National Jewish Health in Denver, Colorado, we have one of the nation’s leading food allergy treatment programs. Learn more about our programs for children and adults, or use the button below to make an appointment.