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Food allergies

close-up of a bowl of peanuts in their shells

About one in four people think that they are allergic to certain foods. In fact, only about 4 percent of persons age 5 and older actually have a food allergy.

In a true food allergy, your body's defense system, called the immune system, reacts to a certain food or food component as if it were a harmful substance. Symptoms of an allergic reaction to a food usually develop within a few minutes to an hour after eating the food.

  • If you are allergic to a particular food, you may first feel itching in your mouth as you start to eat the food.
  • Your nose could become stuffy or itchy.
  • You might start sneezing.
  • Your eyes could itch and develop tears.
  • You may get swelling of the lips, face, tongue, throat, or other parts of your body.
  • After the food reaches your stomach, you may have symptoms such as vomiting, diarrhea, or stomach cramps.
  • Your skin could become red, itchy, or develop a rash.

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Anaphylaxis

For some people, an allergic reaction to a food is uncomfortable but not serious. For others, an allergic food reaction can lead to death. A life-threatening reaction caused by allergy is called anaphylaxis (an-uh-fuh-LAK-suhss). Symptoms of anaphylaxis include:

  • Hoarseness, throat tightness, or a lump in your throat
  • Wheezing, chest tightness, or having a hard time breathing
  • Rapid heart rate
  • Dizziness, lightheadedness, or fainting
  • Tingling in the hands, feet, lips, or scalp
  • Cold, clammy grayish or bluish skin

If you or someone you know is having these symptoms after eating something, call 9-1-1 right away. Anaphylaxis needs emergency treatment with a medicine called epinephrine (ep-uh-NEF-rin).

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Problem foods

In adults, the foods that most often cause allergic reactions include:

  • Shellfish, such as scallops, oysters, shrimp, crayfish, lobster, and crab
  • Peanuts
  • Tree nuts, such as walnuts, cashews, and pecans
  • Fish
  • Eggs

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Similar medical problems

Other medical problems can have some of the same symptoms as a food allergy, such as:

  • Food poisoning from contaminated food or foods containing poisons, such as certain mushrooms
  • Lactose intolerance
  • Irritable bowel syndrome
  • Reactions to large amounts of some food additives, such as MSG (a flavor enhancer)

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Diagnosis and treatment

If you have food allergy symptoms shortly after eating, see a doctor or allergist. If possible, see your doctor when the allergic reaction is occurring. This will help your doctor diagnose your problem.

The best treatment for a food allergy is to avoid eating the foods that cause your symptoms. This may require reading the ingredients on food labels to make sure that the foods don't contain anything that might cause you to have symptoms.

If you have anaphylactic reactions to certain foods, your doctor may give you a prescription for injectable epinephrine. You need to carry this medicine with you at all times so that you or someone you're with can give you an emergency injection if needed.

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Content last updated: June 17, 2008.

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