Food Allergies Symptoms and Treatment

Allergic reactions to food have increase dramatically over the past 20-30 years. Once considered unusual, food allergy now affects 6-8% of young children in the UK and around 1-2% of adults.

There are different forms of food allergy, some are potentially life threatening, others not. A diagnosis of food allergy can have a massive impact on the everyday life of both a patient and their whole family. Food allergies can be daunting, especially for parents with a baby or child who is a sufferer. It is essential for optimal management that all the problem foods are correctly identified and that patients know exactly how to recognise and treat allergic reactions if they occur. It is also important that the common allergic problems such as eczema and asthma, that commonly go hand in hand with food allergy, are identified and treated.

What is a food allergy?

Food allergy is an over-sensitivity to a particular food protein such as milk, egg or a particular nut. Exposure to the allergen causes the release of chemicals in the body that can cause unpleasant and potentially harmful effects. The most severe form is known as anaphylaxis which can be life threatening. Some types of food allergy (often referred to as delayed or non-IgE mediated) can be unpleasant but are not dangerous. These predominantly effect infants and are outgrown in early childhood.

What foods do people tend to have allergies to?

Most food allergies are to a relatively small number of foods. The most common food allergy is to egg but other common allergens include milk, nuts, sesame, fish shellfish, wheat, soya and kiwi. What foods cause allergies is very much influenced by the foods eaten in the family home so will vary in different parts of the world.

What are the signs and symptoms of a food allergy?

Common symptoms of food allergy include:

  • Itchy rash/hives
  • Swelling
  • Runny eyes and nose
  • Abdominal pain, diarrhoea and vomiting

In more severe cases, they can cause

  • Breathing problems
  • Circulatory problems leading to dizziness and collapse due to low blood pressure

Delayed food allergy, seen in smaller children, will present with different problems, which are difficult to diagnose as they are otherwise common in children who do not have food allergy. Food allergy only needs to be considered if they are severe, multiple and treatment resistant These include:

  • Eczema
  • Colic
  • Diarrhoea
  • Gastro-oesophageal reflux (effortless vomiting usually after feeds)
  • Poor weight gain
  • Constipation

Until the underlying allergy is identified and removed, the symptoms may progress and worsen despite aggressive use of treatments such as steroids or other medications.

Food allergy may develop in adult patients as a new problem or may be a continuation of allergies that developed in childhood. Although childhood food allergies will often resolve (especially milk, egg and wheat) some are more inclined to persist (e.g. nuts, sesame, fish, shellfish).

Adults with eczema may also have undiagnosed food allergies, although this is much less common than in children. Sometimes identification of such allergies can help improve eczema symptoms.

Can a food allergy be fatal?

Thankfully fatal reactions to food are very rare, effecting approximately 10-20 people each year in the UK. Careful diagnosis and education around identifying and managing reactions can help reduce the risk.

How are food allergies tested and diagnosed?

A careful, detailed clinical history taken by an experienced physician coupled with allergy tests such as skin prick testing, specific IgE blood testing or provocation challenges remains the most reliable way to reach a diagnosis or exclude allergy as the cause of the problems.

Reassessment of such food allergies can sometimes identify foods that can be safety reintroduced back in the diet. The most common adult food allergies are to fresh fruit and vegetables in people with pollen allergy (known as Pollen Food Syndrome). Adults who have experienced a severe allergic reaction (such as anaphylaxis) should be evaluated by an Allergist, who will consider food allergy as a potential cause. There are many foods which may trigger such new reactions although the most common are seafood, nuts, seeds and fruit/vegetables. In some cases, food allergic reactions only occur when the food is eaten before exercise (Food-Dependent Exercise Induced Anaphylaxis). Therefore anaphylaxis in adults requires assessment with a careful history followed by test to identify the potential culprit. Sometimes this will involve molecular diagnostic testing.

We offer this as well as ongoing holistic care to ensure that food allergy has as little impact as possible on day to day life. This includes working in partnership with expert allergy dieticians.

Is a food allergy treatable or curable?

Some allergies are naturally outgrown but when they aren’t the conventional treatment is to carefully avoid the food and be prepared for a reaction, if it occurs More recently, there has been much research around food desensitisation (also known as immunotherapy or OIT). This involves giving small but increasing amounts of the food to re-train the immune system to be less sensitive. This can mean that small, accidental exposures are much less likely to cause reactions.

What treatments are available for food allergies?

Whilst standard advice in the NHS is to avoid food allergens, there is also another approach known as desensitisation or OIT (Oral Induction of Tolerance). This is a newer approach to food allergies such as milk, egg and peanut that now has a solid scientific grounding and is an area of particular interest at Allergy London.

How do these treatments work?

Oral Desensitisation (OD), also known as Oral Tolerance Induction (OTI or OIT) or food desensitisation, is a treatment that involves giving very small, but gradually increasing amount of the food that the child is allergic to. The intention of this is to increase the tolerance to the food allergen so that larger amounts of it can be taken without causing any symptoms and as a result, allergen containing foods can be eaten safely or at very least, accidental exposures to small amounts of them will not cause reactions.

Do food allergy treatments have any side effects?

Food OIT treatment carries a risk of reactions itself and is not a cure – if the dose of allergen is not continued in the diet, then the effect is lost. The risk of these reactions needs to be balanced against the benefits of the treatment before considering this approach.

Can I get my food allergy treated?

At Allergy London, once there is a clear diagnosis we can discuss the options – whether avoidance or desensitisation and consider together which may be the best option in an individual case.

How much does food allergy treatment cost privately?

This will depend very much on the allergen, the method of desensitisation, which is in turn influenced by the patient’s age. At Allergy London, desensitisation is offered as part of a package to ensure there is no risk on escalating costs.

If you would like to know more then please contact us on

Professor Fox has jointly written a definitive guide to managing your child’s food allergy, with the mother of a food allergic patient ‘The Allergy Free Baby & Toddler Book’ available on Amazon.

Prof Fox has also spoken to The Today Programme on the topic of food allergies.

Written by

Professor Adam Fox

Date reviewed: March 2021

Adam Fox is a Professor of Paediatric Allergy with over 20 years experience in both the NHS and private sector. Professor Fox is Commercial Medical Director at Guy’s & St Thomas’ Hospitals NHS Foundation Trust and Professor of Paediatric Allergy at King’s College London and the founding Director of the KCL Allergy Academy, a postgraduate educational programme, which was a finalist at the BMJ Awards in 2018.

View Professor Fox’s profiles on:

Food Allergies Symptoms and Treatment

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