Allergies to Foods

What is an allergy to foods?
What are the symptoms of food allergy?
What are common food allergies?
How is food allergy diagnosed?
Prevention of food reactions
What is the treatment for food allergy?
What is the role of National Jewish Health ?

What is an allergy to foods?

An allergic reaction to a food is an unpleasant reaction caused by the immune system overreacting to a food. The most common type of food allergy is caused by an overly sensitive immune system that creates IgE antibodies directed against an otherwise harmless protein in the food (allergens). Other types of unpleasant reactions to foods not caused by the immune system are considered to be food intolerances.

Food intolerances have various causes. For example, a person may lack an enzyme needed to digest a portion of a certain food; or, the food may be contaminated by bacterial or other toxins that cause symptoms resembling those of food allergy.

Since so many people have a negative reaction to food at some time in their lives, the public perception of the prevalence of food allergy is skewed. In reality, very few people are truly allergic to foods. However, for those who are allergic, it is important to diagnose the allergy and identify the food so that serious, and even life-threatening, reactions can be avoided.

To learn more about food allergies, listen to our podcast featuring Kirstin Carel, MD.

What are the symptoms of food allergy?

Food allergies may cause many different allergy symptoms. Allergic reactions to food usually occur rapidly after eating the offensive food. Signs and symptoms of food allergy can involve the nose, mouth, skin, lungs, heart and stomach.

• Skin symptoms include itching, flushing (redness), hives, and swelling.
• Stomach symptoms include tingling; burning; abdominal cramping, nausea, vomiting and diarrhea.
• Respiratory symptoms include nasal congestion, runny nose, sneezing, throat swelling, wheezing and/or difficulty breathing.
• Life-threatening anaphylactic reactions to foods may cause a person to lose consciousness and stop breathing. Call 911 immediately if you suspect anaphylaxis.
• Cardiovascular symptoms include lightheadedness, fainting, low blood pressure and shock.

Occasionally, delayed allergic reactions to foods may occur that take hours to several days to develop and may include other symptoms such as decreased appetite, abdonminal pain, chronic diarrhea, failure to gain or maintain weight, rashes and (less frequently) fever and joint aches.

What are common food allergies?

Adverse reactions to foods are fairly common, but true allergic reactions to food determined by food challenges are not very common. Six to 8 percent of babies and young children and 3 to 4 percent of adults have food allergies.

Young children and babies can outgrow food allergies. Eighty percent outgrow allergies to eggs, milk, soy and wheat by school age. New research indicates 20 percent of children may outgrow peanut allergy and 10 percent may outgrow tree nut allergy as they get older.

Most Common Food Allergies

Learn more about what causes allergy.

How is food allergy diagnosed?

Every diagnosis begins with a detailed medical history and thorough physical examination. The doctor will ask lots of questions about the nature of the reaction, where and when it occurs, which foods are thought to cause symptoms, etc. You may be asked to keep a detailed food diary to help in making the diagnosis. Since the possibility to become allergic is inherited, expect some questions about other family members who may be allergic.

Depending upon the findings of the initial evaluation, the following tests may be necessary:

• Allergy skin testing may be performed to check for sensitivity to selected food allergens.
• Laboratory testing is often indicated.
• Food Diary to record what was eaten, when it was eaten, and how long after eating you reacted and what was the reaction and treatment given.
• Food challenges are performed with safety as the highest priority.

Why bother with a food challenge?

Learn more about allergy testing.

Prevention of Allergic Reactions to Food

Here are some simple things you can do to help lead a normal, active life:

• Learn more about your food allergies and how to avoid foods you are allergic to. Talk with your doctor or a registered dietitian. 
• Avoid foods to which you are allergic.
• Know all the different names of foods to which you are allergic. 
• Read labels carefully to identify foods in packages.
• Ask about foods served away from your home.
• Educate adults caring for your children about food allergies.
• Encourage children with food allergies not to eat food given to them by friends.
• Use and understand allergy medications.
• Carry injectable epinephrine (Epi-Pen or TwinJect) and an oral antihistamine such as Benadryl as prescribed for emergencies.

What is the treatment for food allergy?

There is currently no cure for food allergy. As a result, the current management of food allergy involves avoiding the offending food and having the medications necessary for the treatment of allergic reactions to foods available at all times. Injectable epinephrine and antihistamines can be used to alleviate symptoms resulting from accidental exposures, but the recommended approach is complete avoidance of the suspected food.

Learn about the latest allergy treatments and medications.

What is the role of National Jewish Health?

Allergists at National Jewish Health have been working with food allergies for a long time. We can do a comprehensive allergy evaluation to identify the cause or causes of food allergy. National Jewish Health doctors may perform specific skin testing, blood testing or food challenges. Based on your test results and history, the doctor will develop a management plan.  This includes specific things to avoid, how to take care of yourself and treat your allergic reactions.

If you would like additional information on allergies or an evaluation at National Jewish Health, please call LUNG LINE® to speak with one of our nurses.

National Jewish Health allergy shot hours.

Return to Top

This information has been approved by Dan Atkins, MD  (October 2007).