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. Call 999 if you think someone has the symptoms of anaphylaxis, such as: Ask for an ambulance and tell the operator you think the person is having a severe allergic reaction.
Most children that 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.
Types of food allergies
Food allergies are divided into 3 types, depending on symptoms and when they occur.
- IgE-mediated food allergy – the most common type, triggered by the immune system producing an antibody called immunoglobulin E (IgE). Symptoms occur a few seconds or minutes after eating. There’s a greater risk of anaphylaxis with this type of allergy.
- Non-IgE-mediated food allergy – these allergic reactions aren’t caused by immunoglobulin E, but by other cells in the immune system. This type of allergy is often difficult to diagnose as symptoms take much longer to develop (up to several hours).
- Mixed IgE and non-IgE-mediated food allergies – some people may experience symptoms from both types.
What are the symptoms of a food allergy?
Normally food allergy symptoms appear within a few minutes of eating the offending food, although they may be delayed by up to a couple of hours. The symptoms are usually those of ‘classic’ allergy, some of which are listed below:
- Gut reactions: Abdominal pain, vomiting, diarrhoea
- Skin reactions: Itching and swelling (rash or nettle rash)
- Respiratory reactions: Runny nose, sneezing, wheeze, cough
At the bottom of this page you will find our downloadable Food and Symptoms Diary. Use this to track your symptoms to discuss with your GP.
How can I manage my food allergy?
You can find a whole host of useful tips on management and avoidance on our relevant Factsheets below but there are 3 key things to be on top of when it comes to managing a food allergy:
- Identify and avoid the cause (if possible)
- Recognise the symptoms of an allergic reaction by keeping a food diary
- Know what to do if it happens again
Treatment for a food allergy
The best way to prevent an allergic reaction is to identify the food that causes the allergy and avoid it. Research is currently looking at ways to desensitise some food allergens, such as peanuts and milk, but this is not 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 given a device known as an auto-injector pen, which contains doses of adrenaline that can be used in emergencies.