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Allergies Health Center

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Food Allergies - Topic Overview

Kids usually have the same symptoms as adults. But sometimes a small child just cries a lot, vomits, has diarrhea, or does not grow as expected. If your child has these symptoms, see your doctor.

Some people have symptoms after eating even a tiny bit of a problem food. As a rule, the sooner the reaction begins, the worse it will be.

The most severe reaction is called anaphylaxis (say "ANN-uh-fuh-LAK-suss"). It affects your whole body. Anaphylaxis can start within a few minutes to a few hours after you eat the food. And the symptoms can go away and come back hours later. If you have anaphylaxis:

Anaphylaxis can be deadly. If you have (or see someone having) any of these symptoms, call911right away.

A few foods cause most allergies. The protein in a food that causes an allergy is called a food allergen.

  • Milk, eggs, peanuts, tree nuts, fish, shellfish, wheat, and soy cause most problems in children.
  • Milk, peanuts, tree nuts, fish, and shellfish cause most problems in adults.

If you are allergic to one food, you may also be allergic to other foods like it. So if you are allergic to shrimp, you may also be allergic to lobster or crab.

Your doctor will ask questions about your medical history and any family food allergies. And he or she will do a physical exam. Your doctor will also ask what symptoms you have. He or she may want you to write down everything you eat and any reactions you have. Your doctor will consider other possibilities that could be confused with food allergies, such as a food intolerance.

Because food allergies can be confused with other problems, it is important for your doctor to do a test to confirm that you have a food allergy. Your doctor may first start out with either skin testing or a blood test to determine what you are allergic to. But an oral food challenge is the best way to diagnose a food allergy. In an oral food challenge, you will eat a variety of foods that may or may not cause an allergic reaction. Your doctor watches to see if and when a reaction occurs.

A skin prick test can help to find out which foods will cause a reaction. The doctor will put a little bit of liquid on your skin and then prick your skin. The liquid has some of the possible food allergen in it. If your skin swells up like a mosquito bite, your doctor knows that you are allergic to that food. Your doctor may also do blood tests to look for the chemicals in your blood that cause an allergic reaction.

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