Food allergy or food intolerance? Understanding the difference and finding the right support

Ellen Lees
By Ellen Lees,
updated on Apr 14, 2023

Food allergy or food intolerance? Understanding the difference and finding the right support

How to recognise the key differences between the two, and get the right support for you

Whether it’s a celebratory meal out or a hearty, home-cooked dinner with friends, being able to relax and enjoy a good meal with good company is one of life’s little pleasures. But, what if eating out fills you with anxiety due to the onset of digestive issues, feeling nauseous, and potentially even swelling facial features – and you don’t know the cause?

There are a few names used to describe the body’s adverse reaction to food, including allergy, intolerance, and hypersensitivity. And while you may have heard of these, or know someone who experiences this, what is less common knowledge is that it’s actually possible to develop an allergy or intolerance later in life – even if you didn’t struggle with certain foods growing up. So, if you haven’t previously experienced an adverse reaction, how do you tell the difference and what do you do if symptoms arise?

The key difference

Food allergy

A food allergy is when your body’s immune system has an unusual reaction to a particular type of food or ingredient. In some cases, symptoms can be mild, but in others, symptoms can be very serious, and potentially even life-threatening.

There are 14 foods that, legally, food businesses must declare as allergens. And believe it or not, eight of those are responsible for causing 90% of reactions. These include cow’s milk, eggs, fish, peanuts, shellfish, tree nuts, soya, and wheat. Of course, it’s possible that any food type has the potential to have an adverse effect on the body, so keeping a food diary can be helpful to pinpoint any triggers if you’re unsure.

Food intolerance

A food intolerance, despite being highly common, can be more difficult to diagnose. Unlike a food allergy, symptoms of an intolerance aren’t considered life-threatening, but may leave you feeling very unwell for a few hours and impact your daily life. We don’t know what causes food intolerances, however, they are believed to be prompted by certain lifestyles, such as a diet with erratic food intake.

The signs and symptoms

Food allergy

According to the NHS, common symptoms of a food allergy can occur immediately, or up to 48 hours after eating, and include: feeling dizzy or lightheaded, itchy skin, swelling of the lips, face or eyes, coughing, wheezing or shortness of breath, feeling nauseous or being sick, stomach pains, and diarrhoea.

Food intolerance

The most common symptoms of a food intolerance typically involve the gut, such as bloating, wind, stomach pain, and diarrhoea. However, an intolerance can also cause plenty of other symptoms, including feelings of tiredness, nausea, constipation, joint pain, or headaches. These symptoms, while generally mild, can last from a few hours to a couple of days sometimes.

What to do next

Food allergy

If you think you or someone you know is having an allergic reaction, it’s important you call 999 immediately. If no urgent treatment is required, you may be referred to your GP for testing.

These tests may include a skin-prick test, blood tests, or following a particular diet (e.g. avoiding the suspected food to see if your symptoms improve). You may also be asked to keep a food and symptom diary to help identify potential trigger foods.

If you have a food allergy, it’s important you:

  • Check food labels and restaurant menus
  • Alert your family, friends, colleagues etc. about your allergy
  • If needed, carry at least two adrenaline auto-injectors (e.g. an EpiPen*) with you at all times.
  • Tell staff at food places, airlines, and cabin crew about your allergy.
  • Wipe down surfaces before eating in public.

*EpiPens and other auto-injectors have the instructions on the side, so don’t worry if you forget or if someone else has to do it for you. Always call 999 after using the injector, even if symptoms ease.

Food intolerance

When managing a food intolerance, the best thing is to try to avoid eating the food completely, or at least, reduce how much and how often you eat it. But, please seek advice from your GP or a nutrition specialist (e.g. a dietitian) before making any changes to your diet, to ensure you aren’t missing out on essential nutrients that could be vital for your overall health and wellbeing. This is particularly important for children’s growth and development.

According to the FSA (Food Standards Authority) an estimated 2 million people in the UK are living with a diagnosed food allergy.

Working with a dietitian

Discovering you have a food allergy, intolerance, or hypersensitivity can be incredibly frustrating – particularly if it’s related to a type of food you enjoy. But working with a nutritional specialist can be helpful as you get to grips with this new information. They can help you to better understand your trigger foods, and how to adapt your diet to suit your lifestyle. A dietitian can help you with the implementation of an exclusion diet if required, and the reintroduction of foods in future. They can also offer valuable advice on how to avoid the allergen, while still maintaining a healthy, balanced diet that meets your personal needs.

For more information about nutrition, visit the Nutritionist Resource or speak to a qualified nutritionist.

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