Food allergies: what you need to know

profile picture of Christina Merryfield
Senior Specialist Dietitian, Cromwell Hospital
12 May 2023
Next review due May 2026

Food allergies are increasing in the UK. But it can be hard to know if you’re truly allergic to something, or if you’re simply intolerant. It’s important to figure this out, because the treatment for each of these conditions is quite different. Here, I’ll share everything you need to know about food allergies, as well as what to do if you think you have one.

adult and child grocery shopping

What is a food allergy?

Food allergies are common. They usually begin when you are young and may continue throughout your life.

Food allergies can be scary as sometimes they can cause quite severe, and occasionally life-threatening reactions. But for other people, food allergies are mild.

At the moment there is no cure for food allergies. But there is currently ongoing research to see if exposing young children to potential allergens can prevent food allergies from developing. The good news is that food allergies are usually manageable.

Common food allergies include:

  • peanuts
  • tree nuts such as walnuts and almonds
  • eggs
  • cow’s Milk
  • seafood
  • wheat

Many people might think that coeliac disease is a gluten allergy, but it’s actually an autoimmune condition. And while you can be lactose intolerant, a true dairy allergy involves being allergic to the proteins in cow’s milk products.

What causes food allergy?

Food allergies involve your immune system. Normally your immune system does a great job of noticing and removing threats, such as viruses and bacteria, from your body. But sometimes it gets confused.

With food allergy, your immune system reacts to the proteins in certain foods. It mistakenly thinks they are dangerous, and so starts an immune response to try and get rid of it. This is what causes the symptoms of food allergy.

With most food allergies your body produces something called Immunoglobulin E (IgE) antibodies. These will fight against the allergen (food you are allergic to). Your body will also release histamine – a chemical which creates an inflammatory response.

There are also some non-IgE allergies, which are usually mild but can cause eating difficulties in children.

And sometimes you can react to foods if you have a pollen allergy (hay fever). This is because your body can confuse the proteins in pollen with the proteins in certain foods because they appear similar. It’s called pollen food syndrome, and usually leads to local, mild reactions such as itchy lips.

What are the symptoms of food allergy?

The symptoms can vary depending on whether you’re having a mild or severe reaction. Usually, the symptoms of food allergy appear quickly – within seconds or minutes. But they can take up to a few hours to develop.

Here are some of the symptoms of food allergy to look out for:

  • wheezing or breathing difficulties
  • itchy red patches on the skin (hives)
  • itching or tingling in your mouth
  • feeling sick
  • dizziness
  • stomach pain

Occasionally with food allergy you can experience something called anaphylaxis. This is a serious and potentially life-threatening reaction. If you think you or someone near you has anaphylaxis, call 999 immediately.

Symptoms of anaphylaxis include:

  • low blood pressure
  • flushed or pale skin
  • a feeling of tightness in the throat or chest
  • a fast but weak pulse
  • fainting

How do you test for food allergy?

It’s important to get a diagnosis for your food allergy. This is because sometimes the symptoms can be serious. But also, some people who think they’re allergic to a food are actually intolerant and can unnecessarily cut out important food groups from their diet. This can lead to nutritional deficiencies and other health issues.

If you have an IgE food allergy, then you can test for it via a skin prick test. Or sometimes a doctor may suggest you have a blood test to look for IgE antibodies.

When you see a doctor, it can be helpful to show them a food and symptom diary. This is so they can look for any patterns between what you have eaten and any negative effects.

It’s harder to test for non-IgE food allergies. Sometimes an oral food challenge is recommended. This is when you try eating a small piece of the food you think you’re allergic to. It’s done in a safe place like a hospital where the doctor can treat you if you react badly.

Unfortunately, there’s no evidence to suggest that tests looking at strands of your hair can reveal anything reliable about which allergies you might have.

How do you treat a food allergy?

With food allergy, you need to avoid your trigger foods (allergens). This means you should not eat or drink any products that contain them. And you’ll also have to check labels carefully to see if there are any traces of your allergen too. Food manufacturers are legally required to state if their products contain common allergens.

Some product labels also list if the product may be contaminated by small particles of allergens. This may happen if they are using the same premises to prepare their food. Remember to check non-food items too – such as skincare or even cleaning products as these can sometimes include allergens too.

As well as avoiding your trigger, a doctor may also recommend you have treatments ready to use if you need them. This can include antihistamines for mild reactions as well as an auto injecting adrenaline pen (epi-pen).

You might like to carry a card or bracelet with you to show people you have an allergy. And teach your family or friends how to use an epi pen safely if needed. Remember that even if you use an epi-pen you still need to call 999 as anaphylaxis is always an emergency.

What’s the difference between an allergy and an intolerance?

With an intolerance, your immune system is not involved. Instead, your body struggles to digest certain foods. For example, with lactose intolerance, your body doesn’t make enough of the enzyme required to break down the sugar in milk. This can cause bloating and other digestive symptoms, but it won’t make you have a severe reaction.

Most food intolerances are mild although they can sometimes be moderate. The treatment for food intolerance is to reduce or avoid consuming the food you struggle to digest. For lactose intolerance you can also take the enzyme (chemical which helps break food down) called lactase.

For food allergy, its important you avoid your allergen, including any cross contamination as it’s possible you could have a serious reaction.

Infographic: Food allergies: what you need to know

The following infographic highlights some of the key food allergy facts listed below. Click on the image to open a larger PDF version of the infographic (PDF, 0.2 MB).

  • Food allergies can be mild or severe.
  • They involve your immune system.
  • They are more serious than an intolerance.
  • Coeliac disease is not a food allergy.
  • Food allergy symptoms include hives, stomach pain and wheezing
  • Call 999 for: a tight chest or throat, fainting, fast pulse

  • Bupa's food allergy facts infographic

    Are you interested in learning more about your health? Discover more about our range of health assessments.

    profile picture of Christina Merryfield
    Christina Merryfield
    Senior Specialist Dietitian, Cromwell Hospital



    Julia Ebbens, Health Content Editor at Bupa UK

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