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What is Food Allergy?

A food allergy is a medical condition where the body’s immune system over-reacts to a harmless protein that is found in a certain food. For example, many people that are allergic to milk have an allergic reaction to the protein casein [kay-see-en], which is found in milk.

The most common foods that people in the United States are allergic to include:

  • Peanuts
  • Eggs
  • Milk
  • Wheat
  • Fish

In some cases, the symptoms of an allergic reaction can be mild, but in many cases, they can be serious or even life threatening. Reactions to food allergies are unpredictable, so just because you have had a mild reaction before does not mean you will have a mild reaction again. They can become very serious at any time. Because food allergies can be deadly, food allergies should be taken seriously.

Food allergies are not the same thing as food intolerances, even though some of the symptoms may be similar. For example, a milk allergy is not the same as lactose intolerance. Lactose intolerance means the body does not make enough lactase, which is responsible for digesting the sugar in milk. Lactose intolerance is not caused by an overreaction in the body’s immune system, yet people with lactose intolerance may have belly pain, gas, and bloating.

If you suspect you may have a food allergy, it is important to talk to your doctor. Your doctor may recommend that you see an allergist [al-err-jist], a doctor that specializes in allergies, to confirm your food allergy so you can adjust your diet, as needed.

Many times, people develop allergic reactions to more than one food. An allergist may test for associated foods if necessary.

New food allergies may begin at any time, from childhood to adulthood. 


Food allergy symptoms may vary, but will shortly follow if you have eaten a food that you are allergic to. Some food allergy symptoms are as follows.

Skin reactions, such as:

  • rashes (may be itchy and red)
  • hives
  • eczema
  • flushing
  • swelling of the lips, tongue, mouth, face, or throat
  • allergic “shiners” (black eyes)

Digestive system reactions, like:

  • belly pain
  • diarrhea
  • nausea
  • vomiting
  • itching
  • bloating
  • gas
  • cramps
  • swelling of the tongue, throat or mouth

Respiratory system (lungs) reactions, for example:

  • runny nose
  • wheezing
  • asthma 
  • throat tightening
  • difficulty breathing

Cardiovascular system (heart) reactions, including:

  • rapid heartbeat
  • low blood pressure
  • passing out

When to See a Doctor

You should see a doctor if you have any of the symptoms above and suspect that you may have a food allergy. It is important to reach out to your doctor as soon as possible so that you can get the food allergy confirmed, which will allow you to make any changes to your diet, as needed.


At this time, it is not known why a food allergy occurs in some people and not in others. It seems that some allergies may run in families, but not all of the time.

Also, people that have other type of allergic reactions that are not food-related, such as asthma, hay fever, or eczema, may also be more likely to develop food allergies.

Diagnosis and Tests

If you think you have a food allergy, you should ask your doctor about seeing an allergist.

Your doctor may ask you to come in for a physical exam to rule out other disorders that may have similar symptoms. If your doctor does not find any other problems, you may be referred to an allergist for further testing.

An allergist, can perform tests that will help you determine if you have a food allergy. Your allergist may ask you about your family history. Prior to seeing your allergist, you may want to write down any known allergies that may be common to your family.

One of the most common tests to find allergies is an allergy skin test. During the allergy skin test, an allergist will put common allergic reaction triggers on your skin and watch for the signs of an allergic reaction.

Skin tests are a fairly common, routine procedure, and can usually be performed at your doctor’s office. In general, needles are not used and the testing is usually not painful as the device only barely scratches the surface of the skin. Most people don't even bleed during a skin test. 

The allergist, or a nurse, will clean your back with rubbing alcohol. After your back is clean, the allergist will use a device with a drop of the allergen on it to scratch the surface of the skin. This will help the allergen get under your skin which may cause a reaction, a small, temporary rash. You may be tested for many different substances at one time. About 15 to 20 minutes later, your allergist will look at the spots on your back to see if there has been an allergic reaction.

If your allergist sees an allergic reaction, it will be recorded. Once your allergist determines what you are allergic to, he/she will help you create an allergy treatment plan to help you safely manage your allergies. You will know the results of your test before you leave the office.

Allergy tests are considered safe for adults and children of all ages (including infants). However, there are some cases where it may not be a safe option. Make sure to tell your allergist if you have ever had a severe allergic reaction. Also, make sure to tell your allergist about any medications you may be taking, including over-the-counter antihistamines, as these may interfere with your allergy test. If you are taking any medications that may make it so that you are unable to test, your allergist may ask you to stop taking them for up to ten days before the test to make sure they fully clean out of your system. If you have a tendency for severe allergic reactions, skin testing may not be the best way to find your skin allergies. If this is the case, talk to your allergist about other options. Your allergist may be able to perform other tests, such as a blood test, to confirm your allergies.


Currently, there is no cure for food allergies. The only way to prevent reactions is to completely avoid the food you are allergic to. When you have a food allergy, it is important to read the labels for, and ask questions about, the food you eat to make sure that you do not accidentally eat something that you may be allergic to. You may also need to substitute the food you are allergic to for other “safe” foods as you are cooking. For example, if you have an allergy to cow’s milk, you may think about trying other types of milk, such as rice or coconut milk.

In some cases, your food allergy may be so severe that you need to make sure that the food you eat not only does not have the food you are allergic to in it, but also does not come into contact with the food you are allergic to. If this is the case, you should always find out where your food was produced and, when eating at restaurants, make sure your server is aware of your allergy so they can make sure your food is prepared safely.

Your allergist may also give you medicines that will help you manage your food allergy. If you are given medicines, it is important to take them as directed.

As allergies can be deadly, for your own safety, you should ask your allergist to explain anything you don’t understand. With a successful allergy plan, you will be able to reduce or even completely get rid of the signs and symptoms of your allergy, and be able to live a normal life.


At this time, there is no known way to prevent a food allergy. If you have a food allergy, you can work to prevent an allergic reaction by making sure that you do not eat or come into contact with the foods that you may be allergic to.

A food allergy is a medical condition where the body’s immune system over-reacts to certain foods. In some cases, symptoms can be mild, but in other cases, they can be life-threatening.

A food allergy is a medical condition where the body’s immune system over-reacts to certain foods. In some cases, symptoms can be mild, but in other cases, they can be life-threatening.