What is a food allergy?

A food allergy is when your immune system has a bad reaction to a certain food. This is different from a food intolerance, which does not involve the immune system. This is true even though some of the same signs may be present.

What causes a food allergy?

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. Your body releases histamine and other substances. This can cause hives, asthma, itching in the mouth, trouble breathing, stomach pains, vomiting, or diarrhea. It doesn’t take much of the food to cause a severe reaction in highly allergic people.

Most food allergies are caused by these foods:

• Milk

• Eggs

• Wheat

• Soy

• Tree nuts

• Peanuts

• Fish

• Shellfish

Food protein-induced enterocolitis syndrome (FPIES) is also called the delayed food allergy. FPIES often occurs in young babies. It causes vomiting and severe fluid loss (dehydration). The most common cause of FPIES is having milk, soy, or grains.

What are the symptoms of a food allergy?

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

• Severe nausea or vomiting

• Diarrhea

• Stomach cramps or stomach pain

• Red, itchy rash (hives)

• Face swelling

• Eczema

• Itching or swelling of the lips, tongue, or mouth

• Throat itching or tightness

• Feeling dizzy with a lowered blood pressure

• Asthma symptoms such as coughing, runny or stuffy nose, wheezing, or trouble breathing

The symptoms of a food allergy may look like other health problems. Always see your healthcare provider for a diagnosis.

How is a food allergy diagnosed?

If you think you have a food allergy, see your healthcare provider for a diagnosis. He or she will take your health history and do a physical exam. The healthcare provider will do skin or blood tests or both to find out the exact diagnosis. These tests may include:

• Skin prick test

• Blood test

• Oral food challenge

• Trial elimination diet

How is a food allergy treated?

The goal of treatment is to stay away from the food that causes the symptoms. This includes speaking up when you are at a restaurant or at friends’ homes. Let them know that you have a food allergy. Don’t be shy. And be clear that you could have a severe reaction if you eat a food you are allergic to, even in small amounts.

In January 2020, the first treatment for food allergy using oral immunotherapy (OIT) was approved by the FDA for peanut allergy in children. In OIT an increasing amount of the allergic substance is given to the child to make them less likely to react to the substance that causes the allergy.

If you have a food allergy, carry an epinephrine shot to treat emergency reactions. Know how to give yourself this shot. You must be ready to treat any allergic reaction caused by eating a food by mistake that you are sensitive to. You need an emergency kit to stop severe reactions. Talk with your healthcare provider about what to do with the kit. Also consider wearing a medical alert bracelet or necklace

Medicines are available to treat some symptoms of food allergy after the food has been eaten. These medicines may ease nose and sinus symptoms, digestive symptoms, or asthma symptoms.

Right now, no allergy shot treatment is approved to treat food allergies. But research is ongoing. Strictly staying away from the allergy-causing food is the only way to prevent a reaction.

Living with a food allergy

If you have one or more food allergies, eating out can be a challenge. But it’s possible to have a healthy and satisfying meal when dining out. It just means that you may have to plan ahead when you eat out.

Here are some tips for dealing with food allergies when you are eating away from home:

• Know what ingredients are in the foods at the restaurant where you plan to eat. When possible, get a menu from the restaurant ahead of time and look over the menu items.

• Let your server know from the start about your food allergy. Before you order, ask how the dish is made and what is in it. If your server does not know this information or seems unsure, ask to speak to the manager or the chef.

• Don’t go to buffet-style or family-style restaurants. There may be cross-contamination of foods from using the same utensils for different dishes.

• Don’t eat fried foods. The same oil may be used to fry several different types of foods, such as fish.

• Carry your emergency injectable epinephrine whenever you go out to eat. Bring it to restaurants and to other people’s homes.

Another tip for dining out is to carry a food allergy card. You can give it your server or the manager before you order food. A food allergy card contains information about the specific items you are allergic to. It also has more information. This includes a reminder to make sure all utensils and equipment used to make your meal are thoroughly cleaned before use. You can easily print these cards yourself using a computer and printer.

Key points about a food allergy

• A food allergy is when your immune system has a bad reaction to a certain food. Before having a food allergy reaction, a sensitive person must be exposed to the food at least once before.

• Most allergies are caused by milk, eggs, wheat, soy, tree nuts, peanuts, fish, and shellfish.

• Allergic symptoms may begin within minutes to an hour after eating the food. If you think you have a food allergy, see a healthcare provider for a diagnosis.

• Carry an epinephrine shot to treat emergency reactions. Know how to give yourself this shot.

• The goal of treatment is to stay away from the food that causes the symptoms.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.