What is a food allergy?

A food allergy is when the body’s immune system reacts unusually to specific foods. Although allergic reactions are often mild, they can be very serious. In the most serious cases, a person has a severe allergic reaction (anaphylaxis), which can be life-threatening. If you think someone has symptoms of anaphylaxis, call 999 immediately, ask for an ambulance, and tell the operator they are experiencing anaphylaxis.

Most children who have a food allergy will have experienced eczema during infancy. The worse the child’s eczema and the earlier it started, the more likely they are to have a food allergy. It’s still unknown why people develop allergies to food, although they often have other allergic conditions, such as asthma, hay fever and eczema.

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What are the symptoms of a food allergy? 

Food allergy symptoms can vary widely from person to person and can range from mild to severe. They typically occur shortly after consuming or coming into contact with the allergen and can affect different parts of the body. Common symptoms of a food allergy include:

  • Digestive problems: Nausea, vomiting, diarrhoea, abdominal pain, cramps.
  • Skin reactions: Itching, hives (red, raised welts on the skin), eczema (itchy, inflamed skin), redness, swelling.
  • Respiratory issues: Sneezing, runny or stuffy nose, coughing, wheezing, shortness of breath, difficulty breathing, chest tightness.
  • Swelling: Swelling of the lips, tongue, throat, face, or other parts of the body.
  • Cardiovascular symptoms: Rapid or weak pulse, light-headedness, dizziness, fainting.
  • Anaphylaxis: A severe, potentially life-threatening reaction involving multiple systems of the body, characterised by a drop in blood pressure, loss of consciousness, and difficulty breathing. Anaphylaxis requires immediate medical attention.

Symptoms of a food allergy can occur within minutes to a couple of hours after consuming the allergen. In severe cases, anaphylaxis can happen rapidly, within minutes, and requires immediate treatment with adrenaline and emergency medical care.

It’s important to note that the severity and type of symptoms can differ among individuals, and some may experience only mild symptoms while others might have more severe reactions. If someone suspects they have a food allergy based on their symptoms, it’s crucial to speak to a healthcare professional for accurate diagnosis, testing, and guidance on managing food allergies.

Types of food allergies

Food allergies are divided into 3 types, depending on symptoms and when they occur:

IgE-mediated food allergy is the most common type, triggered by the immune system producing an antibody called immunoglobulin E (IgE). Upon subsequent exposure to the same food allergen, the allergen binds to the IgE antibodies on the mast cells, triggering these cells to release various chemical substances, including histamine and other inflammatory mediators. This release of chemicals leads to the symptoms associated with an allergic reaction.

Symptoms of an IgE-mediated food allergy occur a few seconds or minutes after eating. Symptoms can range from mild to severe and may include skin reactions (such as itching, hives, or eczema), digestive issues (like vomiting, diarrhoea, or abdominal pain), respiratory symptoms (such as coughing, wheezing, or difficulty breathing), swelling of the lips, tongue, throat, or face, and in severe cases, anaphylaxis, a potentially life-threatening reaction affecting multiple systems of the body.

Non-IgE-mediated food allergies refer to allergic reactions that occur without involving Immunoglobulin E (IgE) antibodies. Unlike IgE-mediated allergies, these reactions involve different components of the immune system and have a delayed onset.

Mixed IgE and non-IgE-mediated food allergies: Some individuals may experience a combination of both IgE-mediated and non-IgE-mediated responses to certain foods. This type of allergy can present with both immediate (IgE-mediated) symptoms, such as hives or swelling, as well as delayed (non-IgE-mediated) symptoms, such as gastrointestinal disturbances or skin issues.

Food allergy testing and diagnosis

It’s essential for individuals with food allergies to be aware of their specific allergens, read food labels carefully, avoid cross-contamination, and have an emergency action plan in case of accidental exposure. Consulting with a healthcare professional and undergoing allergy testing can help determine specific food allergies and appropriate management strategies.

Diagnosing a food allergy is essential for preventing reactions, managing symptoms, improving quality of life, avoiding unnecessary dietary restrictions, and ensuring proper support and guidance for individuals living with food allergies.

Diagnosing a food allergy is crucial for several reasons:

  • Accurate identification of triggers
  • Prevention of severe reactions
  • Avoidance of unnecessary dietary restrictions
  • Finding the right support and guidance.

If you are looking for help and advice or information, you can call Allergy UK’s Helpline on 01322 619898, they can support you through your food allergy journey and advise on your nearest NHS allergy clinic or consultant.

Types of food allergy testing

There are several types of allergy tests used to diagnose different types of allergies, including food allergies, environmental allergies (like pollen or pet allergies), medication allergies, and others. Some common allergy tests include:

  • Skin Prick Test (SPT): This test involves placing a small amount of allergen extract on the skin (usually on the forearm) and then pricking or scratching the skin to allow the allergen to enter. If a person is allergic to the substance, a raised, red, itchy bump (called a wheal) will appear within about 15-20 minutes.
  • Blood Tests: Blood tests measure the levels of specific IgE antibodies to various allergens in the blood. These tests can identify specific allergens that may trigger allergic reactions.
  • Oral Food Challenge: This involves consuming small amounts of a suspected food allergen under medical supervision to confirm or rule out a food allergy. It’s considered the most accurate way to diagnose a food allergy but is performed in a controlled setting due to the risk of severe reactions.
  • Elimination Diet: This isn’t a test in the traditional sense but a method used to identify food triggers by eliminating suspected allergens from the diet and then gradually reintroducing them while monitoring for reactions.

The choice of allergy test often depends on the type of allergy suspected, the individual’s medical history, and the allergens being tested for. These tests should always be conducted and interpreted by a healthcare professional, such as an allergist or immunologist.

Food allergy vs food intolerance

Food allergy vs food intolerance

It's important to differentiate between a food allergy and a food intolerance. A food allergy involves the immune system, while a food intolerance typically involves the digestive system and doesn't trigger an immune response. Consulting with a healthcare professional and undergoing proper testing can help diagnose food allergies accurately.

Food allergy testing and diagnosing

Food allergy testing and diagnosing

Diagnosing a food allergy is essential for preventing reactions, managing symptoms, improving quality of life, avoiding unnecessary dietary restrictions, and ensuring proper support and guidance for individuals living with food allergies.

Food symptoms diary

Food symptoms diary

A food symptoms diary is a record-keeping tool used to track an individual's dietary intake and any associated symptoms or reactions that may occur afterward. It is particularly useful in cases where there's a suspicion of food allergies or intolerances.

Oral Food Challenge

Oral Food Challenge

This involves consuming small amounts of a suspected food allergen under medical supervision to confirm or rule out a food allergy. It's considered the most accurate way to diagnose a food allergy but is performed in a controlled setting due to the risk of severe reactions.

Treatments/managing a food allergy

The best way to prevent an allergic reaction is to identify the food that causes the allergic reaction and avoid it. Research is currently looking at ways to desensitise some food allergens, such as peanuts and milk, but this is not yet an established treatment in the NHS.

  • Avoid making any radical changes, such as cutting out dairy products, to your or your child’s diet without first talking to your GP. For some foods, such as milk, you may need to speak to a dietitian before making any changes.
  • Antihistamines can help relieve the symptoms of a mild or moderate allergic reaction. A higher dose of antihistamine is often needed to control acute allergic symptoms.
  • Adrenaline is an effective treatment for more severe allergic symptoms, such as anaphylaxis.

People with a food allergy are often prescribed adrenaline auto-injectors, which contain doses of adrenaline that can be used as an effective treatment in an anaphylaxis emergency.

Common food allergies

Several foods are commonly associated with allergic reactions. The most common food allergens are often referred to as the “top 14” and must be clearly labelled on food products sold within the European Union (EU). It’s important to note that there are other less common food allergens, and some individuals may have allergies to specific fruits, vegetables, spices, or other food ingredients.

The Top 14 Allergens

The ‘top 14’ allergens are celery, cereals containing gluten, crustaceans, eggs, fish, lupin, milk, molluscs, mustard, tree nuts, peanuts, sesame, soya and sulphur dioxide (sometimes known as sulphites).

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Oral allergy syndrome

Oral allergy syndrome, also known as pollen-food syndrome, is a hypersensitivity to certain raw fruits, vegetables, and nuts. It typically occurs in individuals who have pollen allergies, especially to certain types of tree, grass, or weed pollen. Many with pollen food syndrome can tolerate fruit and vegetables that are well-cooked.

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Peas and other legumes

Outside of the top food allergies (i.e., milk, egg, wheat, soy, peanut, tree nuts, fish, shellfish), allergies to legumes including peas, are thought to be the next most common allergy.

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Lipid transfer protein allergy

Lipid transfer proteins are proteins found in plant-based foods, including fruit, vegetables, nuts and cereals, and they are designed to protect the plant. Most lipid transfer proteins are found in the skin, pips and seeds of the food.

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Managing a food allergy

Managing a food allergy requires vigilance, awareness, and proactive measures to avoid allergens and manage potential allergic reactions. Here are some essential tips for managing life with a food allergy:

  • Know your allergens: Identify the specific foods that trigger your allergic reactions. This might involve allergy testing conducted by a healthcare professional.
  • Carry medication: Always carry your emergency medication, such as two adrenaline auto-injectors, with you at all times. Ensure that family members, friends, or colleagues also know how to use it.
  • Always read ingredient labels carefully. All pre-packaged food must show a list of ingredients which clearly identifies all the ingredients. There are different regulations for foods that are not pre-packaged and which are prepared on-site in smaller food businesses e.g., a café/sandwich shop/deli. There is still a requirement to provide information on the ingredients and allergen content, but how this information is shared is up to the individual business. They may choose to provide this information in a written form, for example, on a chalkboard, or they may communicate the information verbally.
  • Inform others: Educate family members, friends, caregivers, teachers, and colleagues about your or your child’s food allergy. Explain the severity of the allergy, how to recognise symptoms, and what to do in case of a reaction.
  • Plan ahead: When travelling or attending events, take safe snacks or meals where possible to ensure you have options available. Research restaurants or food options beforehand to find allergy-friendly choices.
  • Be cautious with cross-contamination: Avoid sharing utensils, plates, or cooking surfaces with allergenic foods. Ensure proper cleaning of surfaces to prevent cross-contact.
Food allergen labeling

Food allergen labeling

Food allergen labeling is not only a matter of convenience but a critical element in safeguarding the health and well-being of individuals with food allergies, ensuring they can make safe and informed choices about the foods they consume.

Decoding food allergy labelling

Decoding food allergy labelling

Food labelling can be complex and confusing, leaving many individuals uncertain about the safety of the products they consume. Our new leaflet serves as a practical guide to navigating food labels, providing clarity on allergen information and empowering consumers to make informed choices confidently.

Ingredients Matter

Ingredients Matter

As part of our 'It's Time' campaign, Allergy UK is bringing food allergy conversations back to the top of the agenda so this year we want to remind and raise awareness of why Ingredients Matter. It’s time to acknowledge the often-overlooked daily challenges and anxieties of living with a food allergy.

Translation cards

Translation cards are available from Allergy UK and will ensure others are made aware of your allergy despite any language barriers. The cards feature an allergy alert message, an emergency message and a message for use in restaurants to ensure that your food order is free from the particular allergen that causes your reaction.

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Travelling with a Food Allergy

On this page you will find information about travelling abroad with a food allergy, airline polices for customers with allergies and top tips for holidays, from booking and packing to eating out while you’re there. We have a range of factsheets available on different topics related to travelling with an allergy.

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Allergy recall alerts

Sign up to receive allergy alerts when foods have to be withdrawn or recalled if there is a risk to consumers. This could be because the allergy labelling is missing or incorrect or if there is any other food allergy risk, such as cross-contamination.

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Tamsin and Arlo's Story

Click here to view Tamsin’s story, an inspirational video about her Son Arlo and the difficulties they face as a family managing food allergies.

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