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Food allergy - Introduction 


Food allergy or intolerance?

The major differences between a food allergy and a food intolerance are listed below.

  • An allergy produces specific symptoms, such as swelling of the lips, which usually develops within minutes of eating the food, while an intolerance produces more general symptoms, such as indigestion and bloating, that can develop several hours after eating.
  • Only a tiny particle of food is needed to trigger a food allergy, whereas you would usually need to eat a larger amount of food to trigger an intolerance.
  • The symptoms of a food allergy can be life threatening, whereas the symptoms of a food intolerance, unpleasant as they can be, are never immediately life threatening.

A food allergy is when the immune system generates an adverse reaction to specific proteins found in food.

Symptoms of a food allergy can range from moderate, such as tingling in the mouth and a skin rash, to life threatening, such as a severe swelling of the throat that makes it difficult to breathe. A life-threatening allergic reaction is known as anaphylaxis.

Food types

Any food can potentially cause an allergic reaction, but there are eight types of foods that are responsible for the majority of all food allergies.

In children, the foods that most commonly cause an allergic reaction are:

  • eggs
  • milk
  • soya
  • wheat
  • peanuts

In adults, the foods that most commonly cause an allergic reaction are:

  • crustaceans (shellfish), such as crab, lobster and prawns
  • tree nuts, such as walnuts, brazil nuts, almonds and pistachios
  • peanuts
  • fish

For a full list of the foods that commonly cause allergy, see Food allergy - Causes

How common are food allergies?

Food allergies are common, but they are not as widespread as many people think.

A number of surveys have found that 20-30% of people claim to have a food allergy. However, a Food Standards Agency (FSA) report in 2008 estimated that only 5-8% of children and 1-2% of adults have a food allergy. Some researchers believe that the figure for adults may be slightly higher, at around 3-4%.

The reason why many people think they have a food allergy is that they mistake an intolerance to certain types of food (which does not involve the immune system) for a food allergy (which does).

For reasons that are not fully understood, rates of food allergy cases (but not deaths, see below) have risen sharply over the last two decades. See Causes for more information.


Most children will ‘outgrow’ food allergies to milk, eggs, soya and wheat by the time that they start school.

Peanut allergies are usually more persistent. An estimated 80% of children with peanut allergies remain allergic to peanuts for the rest of their life.

Food allergies that develop during, are first noticed in or persist into adulthood are likely to be lifelong allergies.

There is currently no cure for food allergies. Treatment involves identifying the specific food that triggers the allergic reaction and then avoiding it.

If accidental exposure to an allergy-causing food occurs, anti-allergy medications can be used to relieve the symptoms. In cases of mild to moderate allergic reactions, medications such as antihistamines (which block the effects of a protein called histamine) can be used.

In the case of a severe anaphylactic reaction, an injection of a medication called adrenaline is required. As a precaution, people who have previously experienced an episode of anaphylaxis are often given an adrenaline injection device to carry with them.

Last reviewed: 12/01/2010

Next review due: 12/01/2012


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