Last updated: 15.09.22

How to Recognise the Symptoms of Food Allergies

Across the UK, there are thousands of people that suffer from allergies. Whether it be an intolerance to a specific food they’ve lived with since they were born, or a reaction that has developed over time, food allergies are serious.

Food allergies can range from being very mild to life-threatening. In some instances, people might be unaware that they have an allergy, or indeed if they’re suffering from an allergic reaction. As a result, it’s useful to understand a little bit about the different types that can occur, and how you can recognise the symptoms. 

For those that experience very mild reactions, understanding the signs of a food allergy can be useful to help diet management, but in the case of serious allergies, knowing how to spot symptoms can help to save a person’s life.

Those working with or serving food to members of the public must also be aware of the different types of food allergies and how to recognise them, as acting quickly and being able to identify what may have caused a reaction can massively help to mitigate the damage.

In this article, we take a look at some of the signs and common symptoms of food allergies to help advise on what to look out for, as well as explaining what causes a food allergy and the two different types.

What is a Food Allergy?

A food allergy is a reaction that your body’s immune system has to specific foods or ingredients. Instead of digesting the food as normal, your immune system perceives it as a dangerous or harmful substance and will react in a variety of different ways.

Food allergies can occur on a wide spectrum of severity and cause reactions inside the body or outside it on your skin. Those who suffer from allergies always face the risk that they could have a life-threatening allergic reaction, even if previous reactions have only been mild, so it is best for them to avoid any exposure to the food altogether.

It’s important to note that there are two main types of allergies. There are what are called IgE-mediated food allergies, and non-IgE-mediated food allergies. 

The main difference between the two is that IgE-mediated food allergies will generally present symptoms within seconds or minutes of coming into contact with, or ingesting the food, whereas non-IgE-mediated food allergies tend to present symptoms over a longer period - up to days in some cases.

What Causes a Food Allergy?

Food allergies are caused when the body’s immune system mistakes the protein inside a certain kind of ingredient as a threat, prompting the release of a range of chemicals to try and destroy the perceived ‘threat’ which triggers an allergic reaction. Certain kinds of foods are more likely to cause certain symptoms, but it’s not consistent.

Scientists aren’t 100% sure what causes food allergies. Some genetic links are thought to play a part in who develops food allergies, as children are more likely to have the same allergies that their parents do, and you’re more likely to develop allergies if an immediate family member has asthma. (Source)

People who suffer from eczema or asthma are also more likely to also have allergies to certain kinds of foods.

There has been a recorded rise in the number of people developing food allergies in the past few decades. Again, the true cause of this is still unknown, but some scientists think it could be due to significant changes in diets over the last 30-40 years, whilst others have suggested that it is due to the fact that our environments are much cleaner than they once were, so children’s immune systems are growing slightly weaker. (Source)

Of course, our understanding of allergies is also much better now than it was half a century ago, which means more people may be getting diagnosed with food allergies simply because they can spot the symptoms themselves.

There’s no single identified cause of food allergies, and the fact that there are so many different theories circulating about what might cause them suggests that we still have a way to go before we figure out where these reactions come from. But what we do know is that the body can react with severity if it comes into contact with an allergen, so understanding the symptoms and acting quickly if they occur is very important.

What are the Symptoms of Food Allergies?

The severity of a food allergy varies from person to person, and while in some cases an allergy could be highly dangerous, in others it could be considered more of an uncomfortable inconvenience.

Most of the time, food allergy symptoms develop within a few minutes to two hours of consuming the food, depending on the kind of allergy.

IgE-Mediated Food Allergies

As already mentioned, IgE-mediated food allergies will present symptoms almost straight away. If someone experiences any of the symptoms we’re about to look at, they may be as a result of consuming food they’re allergic to. 

It’s important to bear in mind that not all allergic reactions are equal - some people might experience the following in a very mild way, whereas medical attention may be required for others. You should make your judgement on a case-by-case basis and always listen to the person experiencing the reaction and consider their medical history.

The main symptoms of IgE-mediated food allergies are:

  • A tingling or itching sensation in the mouth, often in the gums
  • Itchy and red rashes that can often be raised
  • Swelling skin, usually constrained to the face and lips or mouth
  • Swelling in the throat and on the neck, causing difficulty or discomfort when swallowing
  • Itchy eyes
  • Sneezing
  • Some breathing difficulties or shortness of breath
  • Dizziness and nausea
  • Diarrhoea and other abdominal pains

In some cases, IgE-mediated food allergy reactions can be considerably more severe, resulting in anaphylaxis, which is also commonly known as anaphylactic shock. Anaphylaxis is a medical emergency with potentially life-threatening consequences, so if you suspect that someone is suffering from this condition, you must call 999 immediately.

Symptoms of anaphylaxis can include all of the above to a more severe degree, in addition to the following more severe presentations:

  • Loss of consciousness
  • Major breathing difficulties and wheezing, caused by construction and tightening of the airways
  • A swollen throat
  • Rapid heart rate
  • Drop in blood pressure
  • Confusion and disorientation
  • A feeling of fear or anxiety

Non-IgE-Mediated Food Allergies

IgE-mediated common symptoms of food allergies are often harder to identify, as they tend to present themselves well after ingestion of the food. These symptoms of delayed food allergies usually mean that the reaction to food is less severe, but people can experience a mixed reaction, so these symptoms may come after a more serious and immediate reaction.

Some of the non-IgE-mediated food allergy symptoms are similar to IgE-mediated ones, such as rashes, and are easy to identify. However, non-IgE-mediated food allergies can cause any of the following symptoms, which are often thought to be the result of a different ailment given the difficulty in connecting them with the consumption of a type of food.

  • Heartburn and indigestion
  • Constipation or loose stools
  • Blood in the stool
  • Pale skin
  • Redness or rashes around the anus, rectum or genitals

Many of the above signs of a food allergy present themselves most frequently in children and babies. For example, colic is a common problem in babies and can be caused by allergies.

How to Treat an Allergic Reaction to Food

The severity of an allergic reaction will determine how you should respond, along with the experience of the person that is having the reaction.

If an allergic reaction is mild, antihistamine medication can be used to relieve symptoms. The faster this is taken, the more effective it is at treating food allergy symptoms and reducing any discomfort.

When someone is more severely allergic to a food product, they may carry an auto-injector that contains adrenaline. This helps to reduce breathing difficulties during anaphylaxis by narrowing blood vessels and counteracting the effect of low blood pressure, which can help to keep someone alive and in a stable condition whilst they wait for medical help.

Many people can use an auto-injector on themselves if they feel a severe allergic reaction coming on. But if you need to administer it, remove the covering of the injector, swiftly and firmly press it into the person’s outer thigh, listen for a ‘click’ and then hold it in place for ten seconds.

If you suspect someone is going into anaphylactic shock, you should always ring 999 and ask for an ambulance. Adrenaline auto-injectors can be used whilst waiting for the ambulance to arrive, but the person who has received the adrenaline should be taken to a hospital afterwards so their condition can be monitored.


What are the common symptoms of food allergies?

Some of the most common symptoms of food allergies include a tingling sensation in and around the mouth, hives from a food allergy on the skin and stomach pain or discomfort. Wheezing and shortness of breath is another fairly common food allergy reaction, usually indicating a more severe reaction if the symptoms get worse or don’t go away.

What are the symptoms of food allergies in babies?

Food allergy symptoms in babies and young children tend to be similar to the signs and symptoms of food allergies in adults, although they can be harder to identify because the child cannot explain what they are experiencing. Often, babies having an allergic reaction to food will develop a food allergy rash, watery eyes and a runny nose, start sneezing, wheezing or coughing, or their eczema or asthma may get worse.

What are the symptoms of dairy allergies?

Those that suffer from dairy allergies tend to experience the same food allergy symptoms as everyone else. This may involve hives or a rash, stomach pain and a stomach upset, wheezing and coughing or itching around and inside the mouth.

Having a dairy intolerance may be confused with having an allergy to dairy products, but the symptoms will be different. If you’re intolerant then you’re likely just to experience stomach pain, heartburn, stool changes and maybe vomiting, but no other symptoms affecting other parts of your body.


The types of food allergies symptoms will vary quite a lot from person to person, and it may be that someone who usually has one type of reaction will suddenly start developing different symptoms. Whether you suffer from an allergy yourself or work in an environment where allergens are present, being aware of these symptoms, particularly anaphylaxis, can have a life-saving impact.

If you’re looking to gain a better overview of the symptoms and causes of food allergies, along with knowledge of what the law requires in order to reduce risks, Virtual College offers an online ’Food Allergy Awareness Training Course’ to ensure compliance with EU Food Information.