Food allergies: identifying the triggers.

An immune system reaction

The consultation covers IgE-mediated food allergies. IgE are antibodies, which are proteins of the immune system. In this type of allergy, they recognise a component of a food and can trigger a reaction, often soon after it is eaten.

Symptoms can affect the mouth, with tingling or swelling, as well as the skin, digestive system or breathing. Some reactions are severe. The nature of the symptoms, how soon they appear and the circumstances of the meal are essential in guiding the assessment.

Discomfort after eating a food is not always an allergy. A detailed account of what happened helps distinguish the possible causes.

A range of foods can be involved

Examples of foods that can cause an allergy include:

• Peanuts
• Tree nuts
• Milk
• Eggs
• Fish
• Crustaceans
• Wheat
• Sesame

This list is not a diet to follow. It does not mean you should avoid these foods. Precautions relate to the triggers identified in your own situation.

An assessment guided by your history

The doctor will discuss which foods you ate, the amount if you know it, and the timing and nature of your symptoms. Ingredient lists, photographs of the reaction and medical reports can be useful.

Skin tests or targeted blood tests may be suggested depending on the information gathered. A positive test does not automatically mean that a food should be excluded. It must be interpreted alongside your clinical history.

In some situations, a food challenge, in which the food is given under medical supervision, can help clarify the diagnosis. This is arranged in an appropriate setting. Do not reintroduce a suspected food yourself to check for a reaction.

Proportionate precautions

Care aims to identify the foods responsible, explain useful everyday precautions and prepare emergency treatment if your situation requires it.

Advice focuses on your confirmed allergies, reading ingredient lists and the circumstances of exposure. The aim is to avoid broad restrictions that can make eating more difficult without a demonstrated benefit for you.

If an emergency plan or adrenaline auto-injector is prescribed, the doctor will explain how to use it. The instructions are tailored to your history and risk.

Allergy, lactose intolerance and coeliac disease: different conditions

Food allergy

This involves an immune reaction to a food. The IgE-mediated allergies described on this page are covered by the consultation.

Lactose intolerance

This is difficulty digesting lactose, the sugar in milk, because of insufficient lactase, a digestive enzyme. It is different from an allergy to milk proteins and is not treated in this consultation.

Coeliac disease

This is an autoimmune disease triggered by gluten, which can damage the intestine. It is different from a wheat allergy and requires a specific assessment. Your GP can refer you to an appropriate professional.

Do not begin a broad exclusion diet based solely on a test or suspicion. Speak to a healthcare professional to arrange an appropriate assessment.