Food allergies
Symptoms of food allergies
Food allergy symptoms can vary from person to person and range from mild to severe. They typically happen shortly after eating or coming into contact with the food you’re allergic to and can affect different parts of your body.
Common symptoms can include:
Swelling
Swelling can happen in the lips, tongue, throat, face or other areas.
Dizziness or fainting
If you feel dizzy or faint, you might have a rapid or weak pulse. You may also feel lightheaded or experience a loss of balance.
Anaphylaxis
In some cases, food allergies can cause anaphylaxis, a serious reaction that needs immediate medical attention. Symptoms of anaphylaxis can include difficulty breathing, a drop in blood pressure and loss of consciousness.
If you think someone is experiencing anaphylaxis, make sure to call 999 immediately and let them know it’s an anaphylactic reaction. Acting quickly can help to save a life.
Food allergy symptoms can appear within minutes or up to a couple of hours after eating the allergen.
If you’re worried about possible symptoms of a food allergy, it’s important to speak to your GP for testing, diagnosis and guidance on managing your allergy safely.
Digestive issues can include:
- Feeling sick (nausea)
- Vomiting
- Diarrhoea
- Stomach pain
- Cramps
Skin reactions can include:
- Itching
- Hives (red, raised bumps on the skin)
- Eczema
- Redness
- Swelling
Breathing problems can include:
- Sneezing
- A runny or blocked nose
- Coughing
- Wheezing
- Chest tightness
- Difficulty breathing
Causes, types & common food allergies
Food allergies occur when the immune system overreacts to certain foods, though the exact cause isn’t fully understood. Any food can trigger an allergy, but some are more likely to cause a reaction. The risk is higher if you or a close family member have allergies, asthma, or eczema.
Common allergy-causing foods include:
- Cow’s milk
- Eggs
- Peanuts, soybeans, peas and chickpeas
- Tree nuts – like walnuts, almonds, hazelnuts, pecans, cashews, pistachios and Brazil nuts
- Shellfish – like prawns, crab and lobster
- Wheat
- Celery
- Mustard
- Sesame seeds
- Lupin flour (used in some baked goods)
Food allergies can vary widely, but some allergens are more commonly associated with reactions. In the European Union (EU), the most common food allergens, known as the ‘top 14,’ must be clearly labelled on food products. However, it’s important to remember that less common food allergens, like certain fruits, vegetables or spices, can also cause reactions in some people.
These allergens are commonly highlighted on food labels to help those with allergies make safer choices.
The top 14 allergens include:
- Molluscs
- Mustard
- Tree nuts
- Peanuts
- Sesame
- Soybeans
- Sulphur dioxide and sulphites
- Celery
- Cereals containing gluten
- Crustaceans
- Eggs
- Fish
- Lupin
- Milk
Types of food allergy
Food allergies fall into 3 types based on how and when symptoms appear:
IgE-mediated food allergy
The most common type of food allergy is IgE-mediated, which happens when your immune system reacts to a food allergen by producing an antibody called immunoglobulin E (IgE). Each time you're exposed to the same allergen, your body may release chemicals like histamine, which can lead to allergic symptoms.
Symptoms appear quickly, often within minutes, and can range from:
- Mild – itching, hives or stomach pain
- Severe – breathing difficulties or anaphylaxis, a life-threatening reaction that needs urgent medical care
Mixed IgE & non-IgE-mediated food allergy
A combination of immediate (IgE-mediated) and delayed (non-IgE-mediated) reactions, like hives followed by digestive issues hours later.
Cow’s milk allergy is one of the most common childhood food allergies, affecting around 7% of babies under 1 year old. Most children outgrow it as they get older.
Oral allergy syndrome is also known as pollen-food syndrome. This condition is a sensitivity to certain raw fruits, vegetables and nuts. It often affects people with pollen allergies, particularly to tree, grass or weed pollen. Many people with oral allergy syndrome can still enjoy well-cooked fruits and vegetables without issues. If you’re worried about food allergies, a GP can help with testing, diagnosis and advice on managing your symptoms.
Beyond the common allergens, legumes, like peas, lentils and chickpeas, are believed to be the next most frequent food allergy group.
Lipid transfer proteins (LTPs) are plant-based proteins found in fruits, vegetables, nuts, and cereals. They’re concentrated in the skin, seeds, and pips of these foods and act as a natural defence mechanism for the plant. If you think you have an allergy to LTPs or any other food, it’s important to speak to your GP for advice.
Diagnosing & testing for food allergies
There are different types of tests to diagnose allergies, whether they’re related to food, the environment (like pollen or pets), medications or other triggers. If you think you have an allergy to something, it’s important to contact your GP. They may refer you to an allergy specialist for testing.
The most suitable test depends on the type of allergy suspected, your medical history and the allergens being investigated. Allergy tests should always be carried out and interpreted by a healthcare professional, like an allergist or immunologist.
Skin prick test (SPT)
This test involves placing a small amount of allergen extract on your skin (usually on your forearm) and gently pricking or scratching it. If you’re allergic, a raised, itchy red bump (called a wheal) will appear within about 15 to 20 minutes.
Blood tests
Blood tests measure levels of specific IgE antibodies to allergens. These tests help identify which allergens may be causing reactions and are useful if skin tests aren’t suitable.
Oral food test
This is the most accurate way to confirm or rule out a food allergy. Under medical supervision, you consume small amounts of the suspected allergen while being closely monitored for a reaction. It’s a controlled test designed to help keep you safe.
Elimination diet
This method temporarily removes suspected allergens from your diet, gradually reintroducing them to identify triggers while monitoring symptoms. You may also need to keep a food and symptom diary to track potential triggers.
Managing & treating food allergies
Living with a food allergy requires being prepared, staying informed and taking proactive steps to avoid allergens and handle any reactions safely.
Be careful with cross-contamination
Avoid sharing cutlery, plates, or cooking surfaces with allergenic foods. Clean surfaces thoroughly to prevent cross-contact.
Inform others
Educating family, friends, caregivers, teachers, or colleagues about your allergy can help. Teach them to recognise symptoms and how to respond to a reaction.
Plan ahead
When travelling or attending events, bring your own snacks or meals to avoid uncertainty. Research restaurants in advance for allergy-friendly options.
Read food labels carefully
Check ingredient labels every time you buy or eat packaged foods. In the UK, allergens must be listed. For on-site food, check menus or ask staff.
Carry your medication
Always carry your emergency medication, like adrenaline auto-injectors (EpiPens). Ensure family, friends, or co-workers know how to use it in an emergency.
Know your allergens
Know which foods trigger your allergies. Allergy testing with a healthcare professional can help you identify them and know what to avoid.
Treating food allergies
If you have a food allergy, the best way to prevent an allergic reaction is to know and avoid the specific food that causes the allergic reaction. When it comes to managing food allergies, there are 2 main types of medications that can help relieve symptoms:
- Antihistamines – for mild to moderate allergic reactions
- Adrenaline – for severe allergic reactions (anaphylaxis)
Antihistamines work by blocking the effects of histamine, the chemical responsible for many allergy symptoms. By doing so, they can help reduce itching, swelling and mild to moderate allergic reactions.
You can buy some antihistamines from a pharmacist without a prescription. It’s a good idea to have some on hand in case of an emergency. There are non-drowsy antihistamines available, which are especially helpful if you need to stay alert or drive.
Some antihistamines aren’t suitable for children under 2. It’s important to speak to your GP about options for younger children.
Adrenaline works quickly to counteract the effects of anaphylaxis. It helps to narrow blood vessels to raise blood pressure and opens airways to make breathing easier. If you or your child are at risk of anaphylaxis, you will be prescribed an adrenaline auto-injector. To use an auto-injector, make sure to follow the instructions. If you’re unsure of how to use them, make sure to speak to your GP or a pharmacist.
To make sure you’re always prepared to use your auto-injector:
- Always carry 2 adrenaline auto-injectors with you. If your child is old enough, encourage them to carry it too
- Wear a medical alert bracelet. It can display information about your allergy and emergency contact details
- Store it correctly. Keep the auto-injector away from extreme temperatures (not in the fridge or car glove box) as this can make the adrenaline less effective
- Check expiry dates. Expired injectors may offer less protection. Some manufacturers offer a reminder service to alert you when it’s time to renew
If you suspect anaphylaxis, don’t delay. It’s better to act early, even if you’re unsure. Adrenaline is life-saving, and early treatment can prevent a reaction from becoming more severe.
Food allergies in babies & children
When it comes to feeding your baby, it’s natural to have questions.
Breastfeeding & formula feeding
For the first 6 months, the NHS recommends exclusive breastfeeding or first infant formula. While breastfeeding doesn’t prevent food allergies, it has many benefits for mother and baby. If you’re pregnant or breastfeeding, you don’t need to avoid common allergens (e.g., peanuts) unless you’re allergic yourself.
If your baby has a cow’s milk allergy and isn’t breastfed, they may need a special formula, speak to your GP for advice.
Weaning & allergy risks
When your baby starts solids (around 6 months), introduce potential allergens one at a time in small amounts to spot reactions.
If they have an allergy, eczema, or a family history of allergies, asthma, or hay fever, consult your GP or health visitor first.
Introducing allergenic foods from 6 months, like other foods, may help reduce allergy risk. Take it slowly and monitor reactions.
From around 6 months, you can start introducing a variety of foods into your baby's diet, including:
- Cows' milk (in cooking or mixed with other foods)
- Eggs
- Foods containing gluten (such as wheat, barley and rye)
- Nuts and peanuts (serve crushed or ground)
- Seeds (serve crushed or ground)
- Soya
- Fish
- Shellfish (make sure it's fully cooked)
Once introduced and well-tolerated, keep offering these foods regularly to reduce the risk of allergies. Delaying peanuts and hen’s eggs beyond 6–12 months may increase allergy risk.
When trying an allergen, start with a small amount. If no reaction occurs, gradually offer more next time to include it in their regular diet.
You don’t need to go one by one, once a food is accepted, keep it in their diet to maintain exposure.
Top tips for introducing new foods
Introducing new foods to your baby is an exciting step, but it’s important to take things slowly and carefully. Here are some helpful tips to guide you through the process and make sure it’s as safe and enjoyable as possible:
- Introduce new foods one at a time so it's easier to spot any signs of an allergic reaction
- Do it at a time when you can keep a close eye on your baby for a few hours afterwards
- If your baby has eczema or a family history of allergies, speak to your GP or health visitor before introducing food allergens
Allergic reactions usually happen quite quickly, within minutes of eating the food, but in some cases, it might take a few hours or even days for symptoms to show. symptoms of a food allergy in children can include:
- Sneezing
- Runny or blocked nose
- Itchy, watery eyes
- Wheezing or coughing
- Red, itchy rash
- Worsening asthma or eczema symptoms
- Feeling sick, being sick or having tummy pain
- Diarrhoea or constipation
Most reactions are mild, but in rare cases, a severe reaction called anaphylaxis can happen. This can cause swelling of the lips and face, breathing problems and a sudden drop in blood pressure.
Anaphylaxis is a medical emergency, make sure to call 999 right away if you suspect it.
If you think your child might have a food allergy, it’s important not to experiment by cutting out major food groups (like milk) from their diet. Doing so could mean they miss out on important nutrients for their growth and development. Instead, make sure to speak to your GP for proper guidance. They can offer advice, support and referrals if further testing is needed.
Food additives, like preservatives, colours and texture enhancers, help keep food fresh to eat for longer. All additives must pass strict safety checks before being used in food products. By law, food labels must clearly list any additives used, including their name, ‘E’ number and function (for example, “preservative” or “colour”).
Allergic reactions to common foods like milk or soya are far more common than reactions to additives. Most children have no issues with food additives, but some may react to certain ones, like sulphites (often found in dried fruits and juices).
If you’re unsure how to introduce new foods or spot the signs of an allergy, speak to your GP for advice and support. We’ve also put together a guide on weaning and feeding your baby.
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Frequently asked questions
The most common food allergens include:
- Celery
- Cereals containing gluten
- Crustaceans
- Eggs
- Fish
- Lupin
- Milk
- Molluscs
- Mustard
- Tree nuts
- Peanuts
- Sesame
- Soya
- Sulphur dioxide and sulphites
These foods are part of the ‘top 14’ allergens that must be clearly labelled on food products in the UK and EU.
Unfortunately, there’s no way to ‘flush out’ or cure a food allergy. The best way to manage a food allergy is to avoid the allergen entirely and be prepared to treat any reactions. We’ve covered this in the ‘Managing & living with food allergies’ and ‘Treating food allergies’ section of the page.
If you’re unsure how to manage your food allergy, make sure to speak to your GP for advice and support.
Hives, also known as urticaria, are a common symptom of food allergies. They can appear as raised, itchy red welts on the skin and often develop soon after eating a food allergen.
Foods that can commonly cause allergic reactions include:
- Milk
- Eggs
- Peanuts
- Tree nuts (like walnuts, almonds and cashews)
- Shellfish (like prawns, crab and lobster)
- Fish
- Soy
- Wheat
If you get hives after eating, it’s important to speak to your GP to help confirm the cause.
Yes, it’s possible to develop food allergies as an adult, even if you’ve never had allergies before.
While food allergies are more commonly diagnosed in childhood, adults can suddenly become allergic to foods they’ve eaten without issue in the past.
Common triggers for adult-onset food allergies include:
- Shellfish
- Fish
- Tree nuts
- Peanuts
If you think you’ve developed a food allergy, it’s important to speak to your GP for diagnosis and advice on managing your symptoms.
To help reduce the risk of your child developing food allergies, you can follow these tips during weaning:
- Start introducing foods that can trigger allergies (for example eggs, peanuts and dairy) from around 6 months old, along with other solid foods
- Introduce one food at a time. You can offer these foods in very small amounts, one at a time, to spot any potential reaction
- Once food allergens are introduced and tolerated, continue to include these foods in their regular diet to help minimise the risk of an allergy developing
Some evidence suggests that delaying the introduction of peanuts or eggs beyond 6-12 months may increase the risk of developing an allergy to these foods.
If your baby has a family history of allergies, asthma, eczema or already has a food allergy, you need to be careful when introducing new foods. You should make sure to speak to your GP first.
Most people feel better quickly, often within an hour, after treatment for an allergic reaction. However, it’s important to stay vigilant, as there is a small chance the reaction could return within a few hours if the medication wears off or if you're still exposed to the allergen.
In some cases, an allergic rash may take several days or even weeks to fade. If you're feeling well otherwise and have no other symptoms, there’s usually no need to worry. If you're concerned or the rash persists, speak to your GP for advice and reassurance.
If your symptoms get worse, it’s important to seek medical advice.
The key difference between a food intolerance and a food allergy is how your body reacts to certain foods. A food allergy involves the immune system reacting to a specific food. Symptoms can happen quickly and may include hives, swelling, difficulty breathing or in severe cases, anaphylaxis. Even tiny amounts of the allergen can trigger a reaction.
A food intolerance doesn’t involve the immune system. The symptoms, like bloating, stomach pain or diarrhoea, tend to develop more slowly and are usually linked to the amount of food consumed. Intolerances, like lactose intolerance, are often less serious but can still affect quality of life.
If you’re unsure whether your symptoms are due to an allergy or intolerance, make sure to speak to your GP.
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