Food allergy  


Food allergy and intolerance myth buster

There is much in the media about food allergies and intolerances, but what is the difference? And can you tell fact from fiction?

Food allergy and intolerance myth buster

What is 'food intolerance'?

A food intolerance is not the same as a food allergy.

People with a food intolerance may have symptoms such as diarrhoea, bloating and stomach cramps. This may be caused by difficulties digesting certain substances, such as lactose. However, no allergic reaction takes place.

Important differences between a food allergy and a food intolerance include:

  • The symptoms of a food intolerance usually only occur several hours after eating the food.
  • You need to eat a larger amount of food to trigger an intolerance than an allergy.
  • Unlike an allergy, a food intolerance is never life-threatening.

Read more about the difference between food allergy and food intolerance.

Five facts about allergies

Around one in four people in Britain suffer from an allergy, and it's got worse in the last 10 years

A food allergy is when the body's immune system reacts abnormally to specific foods.

Allergic reactions are often mild, but they can sometimes be very serious.

In children, common food allergies include being allergic to milk and eggs. In adults, allergies to fruits and vegetables are more common. Nut allergies, such as being allergic to peanut, are relatively common in both children and adults.

Symptoms of a food allergy can affect different areas of the body at the same time. Some common symptoms include:

  • an itchy sensation inside the mouth, throat or ears
  • raised itchy red skin rash (this is known as urticaria or hives)
  • swelling of the face, around the eyes, lips, tongue and the roof of the mouth (this is known as angioedema)

Read more about the symptoms of food allergies.


In the most serious cases, a person has a severe allergic reaction (anaphylaxis), which can be life-threatening.

If you suspect that somebody is experiencing the symptoms of anaphylaxis, such as breathing difficulties and swollen lips, immediately call 999 for an ambulance and tell the operator that you think the person has anaphylaxis or 'anaphylactic shock'.

What causes food allergies?

Food allergies are caused when the immune system (the body’s defence against infection) mistakenly treats proteins found in food as a threat to the body.

It releases a number of chemicals to prevent what it sees as an infection taking hold. It is these chemicals that cause the symptoms of an allergic reaction.

Any food could cause an allergic reaction, but there are certain foods that are responsible for most food allergies.

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

  • milk
  • eggs
  • peanuts
  • tree nuts
  • fish
  • shellfish

The majority of children with a food allergy have a background of eczema (an allergic skin condition) during infancy. The worse their eczema is and the earlier it started, the more likely they are to have a food allergy.

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

  • some types of fruit such as apples, pears, kiwi fruit and peaches
  • some types of vegetables such as potatoes, carrots, celery and parsnip
  • crustaceans (shellfish), such as crab, lobster and prawns
  • tree nuts, such as walnuts, brazil nuts, almonds and pistachios
  • peanuts
  • fish

It is still uncertain why people develop allergies to food, although often people with a food allergy have other allergic conditions such as asthma, hay fever and eczema.

Read more information about the causes and risk factors for food allergies.

Types of food allergies

Food allergies are divided into three types, depending on the symptoms and when they occur.

  • IgE-mediated food allergy - the most common type, triggered by the immune system producing an antibody called immunoglobulin E (IgE). Symptoms occur a few seconds or minutes after eating. There is a greater risk of anaphylaxis with this type of allergy.
  • non-IgE-mediated food allergy - the allergic reactions are not caused by immunoglobulin E but by other cells of the immune system. This type of allergy is often difficult to diagnose as symptoms take much longer to develop (up to several hours or even days later).
  • mixed IgE and non-IgE-mediated food allergies - some people may experience symptoms of both types.

Read more information about the symptoms of a food allergy.

Oral allergy syndrome

A relatively common type of food allergy in adults is known as oral allergy syndrome.

This type of food allergy causes itching, tingling and swelling of the mouth, lips and /or throat.

Oral allergy syndrome is most commonly triggered by fresh fruit, vegetables and nuts.

Allergy UK has more information on oral allergy syndrome.


There is no treatment to cure a food allergy. The best way of preventing an allergic reaction is to identify the type of food that causes the allergy and then avoid it in future.

Read more about identifying foods that cause allergies (these are known as allergens).

However, avoid making any radical changes to your child’s diet, such as cutting dairy products, without first consulting with your GP.

A type of medication called an antihistamine can help relieve the symptoms of a mild to moderate allergic reaction. A type of medication called adrenaline is an effective treatment for anaphylaxis.

People with a food allergy are often given a device, known as an auto-injector pen, which contains dosages of adrenaline that can be used in case of emergencies.

Read more about the treatment of food allergies

When to seek medical advice

If you suspect you or your child may have a food allergy, it's very important to ask for a professional diagnosis from your GP, who can refer you to an allergy clinic.

The National Institute for Health and Care Excellence has also released a short guide for parents (PDF, 104kb) who are concerned that their child has a food allergy.

Many parents mistakenly assume their child has a food allergy when in fact their symptoms are due to a completely different condition.

Commercial allergy-testing kits are available, but their use is not recommended. Many kits are based on unsound scientific principles and even if they are reliable, it is best to have the results interpreted by a health professional.

Read more about diagnosing food allergies.

Who is affected

Most food allergies affect younger children aged under the age of three. It is estimated that around one child in every 14 children of this age has one or more food allergies.

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

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

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

For reasons that are unclear, rates of food allergies have risen sharply in the last 20 years.

However, deaths from anaphylaxis-related food reactions are now very rare. There are around 10 deaths related to food allergies in England and Wales every year.

Page last reviewed: 23/10/2013

Next review due: 23/10/2015


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The 3 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Jane1234 said on 25 February 2013

The good news if you have a food intolerance vs food allergy is that you can take key steps to address the underlying problem namely restoring your gut health. Probiotics are key here. People who have a number of food intolerances, typically dairy, gluten, egg, often have "leaky gut syndrome". I recommend they google this. Please also ensure you are getting adequate vitamins and minerals if eliminating foods.

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Valeria said on 12 November 2012

there is a factual mistake in this page. Food intolerance can be fatal, sulfites intolerance can cause anaphylaxis in asthmatics. Please rectify the information on this page.

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lchic said on 13 July 2012

Being allergic to cheese has got to be one of the worst food allergies to have. What doesn't have cheese? Or better yet, what doesn't have milk in it? I was recently rushed to the urgent care because I found out I was allergic to watermelon and my entire throat swelled up. Needless to say, it was one of the scariest things I've ever gone through. I thank for helping me that day. Thanks for sharing this it's definitely important that people know the different food allergies to avoid these instances.

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