Food allergy vs food intolerance

If you find some foods make you feel unwell, there could be many causes, including food allergy or food intolerance. But do you know the difference between them?

One of the biggest differences is the speed at which you’re affected. An allergic reaction often starts soon after you come into contact with the food that causes it, and in very severe cases can be life threatening (this severe type of allergy is called anaphylaxis).

If you have an intolerance to a certain food, on the other hand, it’s much more likely to trigger symptoms gradually. However, while a food intolerance may not be as serious as an allergy, it can still make you feel unwell and affect your day-to-day living.

The main differences to look out for include the following:


  • Symptoms come on within seconds or minutes of eating.
  • Classic food allergy symptoms include rash, wheezing and itching.
  • The most common foods that cause allergies among adults include fish, shellfish and nuts.
  • Children are often allergic to milk and eggs in addition to peanuts, other nuts and fish.
  • Even a tiny trace of food can cause a reaction.
  • Food allergies can be easily diagnosed with tests.


  • Symptoms usually come on more slowly and tend to be long lasting.
  • Typical symptoms include bloating, stomach cramps, diarrhoea, constipation, migraine, lethargy and a general feeling of poor health.
  • It can be difficult to identify which foods are to blame, as it’s possible to be intolerant to several different kinds.
  • A reasonable amount of food is usually needed to cause a reaction (though some people can be sensitive to small amounts).
  • Food intolerance is difficult to diagnose as there are only a few reliable tests available (advice from the government health watchdog NICE claims tests including IgG testing, Vega testing, hair analysis and kinesiology are unreliable).

What next?

Food allergies can be very serious, so if you think you’re affected by one see your GP for a diagnosis. If you have a severe food allergy, you may be prescribed medicines that could save your life in a medical emergency – keep these with you at all times.

Meanwhile it’s essential to avoid the food that’s causing the reaction. This means checking food labels carefully and making you know exactly what ingredients are in the food you eat when you’re dining out.

If you suspect you have an intolerance to a food or type of food you may think it’s a good idea to cut them out of your diet too. However speak to your GP before you do, as not eating a particular food or type of food may cause nutritional deficiencies, which can have an impact on your health in general.

Your local Careway pharmacist can give you lots more tips if you have a food allergy or intolerance. Find your nearest Careway pharmacy by using our Pharmacy Finder.