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Food Allergy

On this page you will find information about all kinds of food allergy, including nut allergy, egg allergy, milk allergy and allergy to sesame and other seeds. You can also find information about a range of food intolerances such as lactose intolerance, gluten intolerance and histamine intolerance, as well as reactions to wheat and irritable bowel syndrome (IBS). We have factsheets available to help you work out whether you have a food allergy or intolerance and we can also provide support when it comes to identifying your food intolerance. You can find all of our factsheets at the bottom of this page.

What is Food Allergy?

Food allergy is caused when the body mistakenly makes an antibody (IgE) to 'fight off' a specific food. When the food is next eaten (or sometimes is just in contact with the skin) it triggers an immune system response which results in the release of histamine and other substances in the body.

These cause various symptoms, depending on where in the body they are released. Very rarely the immune system chemicals are released throughout the body, causing a 'systemic' reaction (such as anaphylaxis).


Allergy UK are providing a free masterclass for Healthcare Professionals on this subject.

What Could I Be Allergic To?

You can be allergic to any food substance. Some of the more common food allergies are peanut allergy; tree nut allergy; egg allergy; milk allergy (dairy allergy); wheat allergy; fish allergy; soya allergy and sesame allergy. Some people also suffer from alcohol allergy, mustard allergy and fruit and veg allergy.

What Are the Symptoms of Food Allergy?

Normally food allergy symptoms appear within a few minutes of eating the offending food, although they may be delayed by up to a couple of hours. The symptoms are usually those of 'classic' allergy, some of which are listed below:

Gut reactions:

  • Abdominal pain
  • Vomiting
  • Diarrhoea;

Skin reactions:

  • Itching
  • Swelling (rash or nettle rash)

Respiratory reactions:

  • Runny nose
  • Sneezing
  • Wheeze
  • Cough

At the bottom of this page you will find our downloadable Food and Symptoms Diary. Use this to track your symptoms to discuss with your GP.

What Is the Difference Between Food Allergy and Intolerance?

Food allergy is quite uncommon and normally causes symptoms within a few minutes of eating the offending food or being in contact with the relevant substance. Food intolerance (non-allergic hypersensitivity) is much more common. The onset of symptoms is usually slower and may be delayed by many hours after eating the offending food; the symptoms may also last for many hours, even into the next day. Some common food intolerances include lactose intolerance; gluten intolerance and histamine intolerance.

You can find more information about the differences in our downloadable Food Allergy or Food Intolerance? Factsheet.

Food Allergy or Food Intolerance can affect you when going out for a meal. Find out information about the top 14 food allergens.

What Are the Top 14 Food Allergens in the UK?

There are 14 major allergens which need to be mentioned (either on a label or through provided information such as menus) when they are used as ingredients in a food product or meal. 

The top 14 allergens are: Celery; Cereals containing gluten; Crustaceans; Eggs; Fish; Lupin; Milk; Molluscs; Mustard; Nuts; Peanuts; Sesame seeds; Soya and Sulphur dioxide (sometimes known as sulphites).

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Common Food Intolerances

Histamine Intolerance

Histamine, tyramine and phenyl ethylamine are vasoactive amines (also known as Biogenic Amines), chemicals which occur naturally in certain foods.

Most people tolerate the amounts found in a normal diet. However, some people experience symptoms to even normal levels of vasoactive amines, which may be due to a reduced ability to break them down in their digestive systems. Symptoms of histamine intolerance include:

  • Headaches,
  • Rashes, flushing
  • Runny or blocked nose
  • Diarrhoea, nausea or vomiting

Symptoms may occur 30 minutes or longer after eating and the level of intolerance does vary from person to person

Once food allergy or other causes have been ruled out, the best way to establish if vasoactive amines are causing symptoms of histamine intolerance is to try avoiding them for 2-4 weeks. Symptoms need to be monitored by keeping a food and symptoms diary; then by reintroducing foods gradually, you can see how much can be tolerated and how often.

Foods high in histamine, which may cause histamine intolerance, include wine and cheese.

Lactose Intolerance

This is a common disorder arising from an inability to digest lactose (milk sugar) because of low levels of the enzyme lactase. Lactose is the main sugar in milk and milk products from mammals (e.g. humans, cows, goats). Lactose intolerance is often confused with milk allergy, but it is NOT an allergy.

The symptoms of lactose intolerance are:

  • Diarrhoea
  • Bloating
  • Flatulence (wind)
  • Abdominal pain or discomfort
  • Infantile colic

And less commonly, it can cause constipation and nausea.

Lactose intolerance is treated by following a low lactose diet. Most children and adults with lactose intolerance can tolerate small amounts of lactose in foods. Lactose may act as a prebiotic - feeding healthy gut bacteria and improving the absorption of minerals such as calcium, so try to include it if you can.

Gluten Intolerance

Gluten intolerance is a comparatively newly recognised condition, although there is still a lot of controversy as to whether or not it exists and whether it is caused by gluten or another protein found in wheat. It is unclear if it is an intolerance or whether the immune system is involved and it is also unclear if it is life long or whether it is a temporary condition.

Patients commonly report a mixture of symptoms in response to eating wheat which include:

  • Abdominal pain
  • Altered bowel habit
  • Bloating
  • Nausea
  • Reflux

However gluten intolerance is also associated with symptoms outside the gut such as:

  • Foggy mind
  • Joint pains
  • Fatigue
  • Depression
  • Headaches
  • Anxiety
  • General lack of well being

Presently there are no tests for gluten intolerance and diagnosis is made by excluding coeliac disease and wheat allergy and using wheat elimination to see if symptoms resolve followed by wheat reintroduction to determine if symptoms reappear. Patients should be referred to a specialist dietitian who can guide them through the appropriate dietary regimen.

How Can I Manage Food Allergy?

You can find a whole host of useful tips on management and avoidance on our relevant factsheets below but there are 3 key things to be on top of when it comes to managing a food allergy:

  1. Identify and avoid the cause (if possible)
  2. Recognise the symptoms of an allergic reaction by keeping a food diary
  3. Know what to do if it happens again

For more detailed information about food allergy, food intolerances, allergy medications, or for more useful tips on management and advice on shopping and cooking for a restricted diet, please find further useful resources below…

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