What is a food allergy?

A food allergy is an abnormal response of the body's immune system to certain foods. This is not the same as food intolerance. But some of the symptoms may be very similar.

What causes food allergies?

Your body’s immune system fights off infections and other dangers to keep you healthy. When your immune system senses that a food or something in a food is a “danger” to your health, you may have a food allergy reaction. Your immune system sends out IgE (immunoglobulin E) antibodies. These react to the food or substance in the food. They cause special cells to release chemicals in the body. This can cause allergy symptoms such as hives, lip and mouth swelling, asthma, itching in the mouth, trouble breathing, stomach pains, vomiting, or diarrhea.

Which foods most often cause food allergies?

Most food allergies are caused by these foods:

• Milk

• Eggs

• Wheat

• Soy

• Tree nuts

• Fish

• Shellfish

• Peanuts

Some facts about food allergies:

• Eggs, milk, and peanuts are the most common causes of food allergies in children.

• Peanuts, tree nuts, fish, and shellfish commonly cause the most severe reactions.

• Nearly 1 in 20 children younger than age 5 have food allergies.

• From 1997 to 2007, food allergies increased by 18% among children under age 18.

• Most children "outgrow" their allergies to egg and milk. But allergies to peanuts, tree nuts, and shellfish may be lifelong.

• According to the National Institute of Allergy and Infectious Diseases, it doesn't take much food to cause a severe allergic reaction. Even a tiny amount (1/44,000 of a peanut) can cause a severe reaction in a highly allergic person.

What are the symptoms of food allergies?

Allergic symptoms may begin a few minutes to an hour after eating the food. Symptoms can be different for each person. Symptoms may include:

• Lip and mouth swelling and itching

• Tightness in the throat or hoarse voice

• Nausea and vomiting

• Diarrhea and cramps

• Itchy, raised bumps (hives)

• Skin swelling

• Itching

Many of these symptoms may be caused by other health problems. Always talk with your healthcare provider for a diagnosis.

What are severe symptoms of food allergy?

Anaphylaxis is a severe allergic reaction. It is life-threatening. Symptoms can include those above as well as:

• Trouble breathing or wheezing

• Feeling as if the throat is closing or that the lips and tongue are swelling 

• Skin gets warm and red (flushed )

• Itchy palms and soles of feet

• Feeling faint

• Nausea

• Fast pulse

• Low blood pressure

• Loss of consciousness

Anaphylaxis is a medical emergency. Call 911 to get help right away. Severe allergic reactions are treated with epinephrine. If you know you have severe allergies, you should carry an emergency kit with 2 epinephrine autoinjectors.

Treatment for food allergies in adults

The goal of treatment is to stay away from the food that causes the allergic symptoms. There is no medicine to prevent food allergies. But research is ongoing.

You need to be prepared in case you eat something with the food that causes your allergic reaction. If you are at risk of a severe reaction, talk with your healthcare provider about getting epinephrine auto-injectors. These should be used if you have a reaction. Carry these with you at all times.

Treatment for food allergies in children

As in adults, it's very important for your child to stay away from foods that cause allergies. But new research shows that children at high risk for peanut allergy may need to be introduced to peanut products early in life (between ages 4 and 6 months), instead of avoiding all peanut-containing food. Early exposure may help prevent peanut allergies. Discuss this information with your child's healthcare provider before giving peanut products to your baby. If you are breastfeeding your baby, talk with their provider to see if it's safe for you to have foods that contain peanuts.

There is now a treatment for peanut allergy in children that uses oral immunotherapy (OIT). In OIT an increasing amount of the allergic substance is given to the person to make them less likely to react to the substance that causes the allergy.

You may need to give vitamins to your child if they can't eat certain foods. This can help prevent any nutritional deficiencies. Discuss this with your child's healthcare provider.

If your child is at risk of a severe allergic reaction, talk with your child's provider. Ask about getting epinephrine auto-injectors for use in case of a reaction. Two epinephrine auto-injectors should be with your child at all times. If your child is in school, meet with the principal and teachers. Tell them about your child's food allergies. And help them create an emergency plan in case your child has an allergic response to a food allergen. Make sure that appropriate school staff have immediate access to 2 epinephrine auto-injectors at all times, including on the playground and for field trips.

Talk with your child's healthcare provider about seeing an allergist for allergy testing. Many children's allergies change over time. As some children grow older they are able to safely bring foods back into their diet. This should be done with an allergist's supervision.