People sometimes use “allergy” and “intolerance” interchangeably, but the difference matters. It affects the type of reaction, the medical assessment needed and the emergency advice a person may be given.

Food allergy

An immune-system reaction

Symptoms can affect the skin, breathing, circulation or digestive system. Reactions may happen quickly and can include anaphylaxis. Even a small amount may cause a reaction for some people.

Food intolerance

Usually a digestive response

Symptoms often involve bloating, abdominal pain, diarrhoea or feeling unwell. They may develop several hours after eating and can depend on the amount consumed.

Why self-diagnosis can create problems

Similar symptoms can have different causes. Removing multiple foods without clinical or dietetic advice may make it harder to identify the real issue and can lead to nutritional gaps. The NHS advises speaking with a GP when food-allergy symptoms are suspected or symptoms repeatedly occur after eating.

  • Keep a clear record of the food, amount, timing and symptoms.
  • Record medicines taken and whether symptoms improved or worsened.
  • Do not deliberately reintroduce a suspected allergen to test a severe reaction.
  • Follow the diagnosis and emergency plan provided by a qualified clinician.

Coeliac disease

Coeliac disease is neither a food allergy nor a simple intolerance.

It is an autoimmune condition in which eating gluten damages the small intestine. Anyone concerned about coeliac disease should seek medical advice before removing gluten, because testing is more reliable while gluten is still being eaten.

Accurate information still matters for everyone

The mandatory UK allergen rules focus on 14 categories, but people may need information about other ingredients too. A business should not minimise a request because the person describes an intolerance rather than an allergy. Clear ingredient information allows the customer to make an informed decision within their own medical advice.

Emergency action

Suspected anaphylaxis is a medical emergency.

Use an adrenaline auto-injector if available, call 999 and say that you think it is an anaphylactic reaction. Follow the instructions on the device and your personal emergency plan.

Read NHS anaphylaxis guidance ↗

Evidence base

Official sources