Food Allergy and Food Intolerance: Assessment and Testing

How do allergy and intolerance differ?

Food allergy involves the immune system reacting to a food. Food intolerance is a different response and does not usually involve that allergic mechanism. The NHS provides separate guidance for the two. Similar everyday labels can hide different risks, so describe the reaction rather than deciding its category from a website alone. [2] [3]

Say what you ate, what happened and how soon it began. Include if the same food has been eaten without a problem at other times and if treatment was needed. Keep any hospital or allergy-clinic records. The sequence of events can be more useful than a broad statement that a food does not agree with you.

If your main concern is persistent digestive symptoms without a clear reaction pattern, Gut Health and Persistent Digestive Symptoms provides a separate starting point. A digestive symptom should not by itself be attributed to food allergy, and an allergy concern should not be reduced to a general gut-health label before its risks are understood.

Why does the history come before the test?

BSACI describes the clinical history as needed in suspected food allergy and advises focusing testing on foods reported to cause symptoms. A test result needs to be interpreted in that context. Testing many foods without a relevant history can create labels that do not explain the problem you came to discuss. [4]

Bring the full result if you have already bought a panel. Note which foods you have removed and what changed afterwards. It is helpful to distinguish the report's advice from changes advised by a clinician. You do not need to hide a past purchase or defend the choice to have it reviewed.

Ask the clinician to state the working question. Is the concern an immediate allergic reaction, a delayed pattern, an intolerance or another explanation for symptoms? You should know why the planned next step fits that question and what would lead to a different route.

Which tests may help with suspected allergy?

For suspected IgE-mediated food allergy, BSACI identifies skin-prick testing and food-specific IgE blood testing as useful first-line methods when chosen and interpreted with the history. IgE is an antibody involved in this type of allergic response. A positive result alone is not the same as a confirmed clinical allergy. [4]

BSACI describes oral food challenge as a specialist diagnostic method. Do not test a suspected allergy by deliberately eating the food at home. Ask which service is right and what supervision is required for any planned reintroduction. This page does not provide a challenge schedule or guidance for testing a reaction yourself. [5]

Why are IgG intolerance panels problematic?

The BSACI Choosing Wisely resource states that food-specific IgG antibodies do not indicate allergy or intolerance and can occur in healthy people without symptoms. A colour-coded list of reactions may therefore look more definite than the evidence allows. It should not be used as a diagnosis or an automatic list of foods to remove. [1]

BSACI also lists hair analysis, bioresonance and several other alternative methods as invalid diagnostic tests for food allergy. The number of items tested does not fix a method that lacks diagnostic validity. Ask what evidence supports the test's planned use, rather than judging it by how detailed the report appears. [6]

If you have received a commercial offer, ask for the exact method before paying. Allergy testing and intolerance testing are sometimes used as broad sales terms for different products. A useful explanation should name the method, its limits and the clinical choice it could support without promising to reveal each food causing symptoms.

What are the risks of removing many foods?

Unnecessary food restriction can reduce nutritional adequacy and quality of life, and an incorrect food label can delay review of another cause. These are among the risks set out in BSACI's alternative-testing guidance. A long exclusion list should therefore be reviewed in context, with attention to what you can safely and practically eat. [1]

Tell the clinician if meals have become difficult, costly or anxiety-provoking. Bring a list of foods you avoid and why each was removed. Ask if dietetic support is right and how the plan will be reviewed. The aim should be a clear, supported choice rather than indefinite restriction based on a single commercial report.

Do not reintroduce a food linked with a suspected serious reaction simply because you have read that a test is unreliable. The reaction history still needs assessment. Questions about avoiding and reintroducing foods should be handled through the right clinical pathway, especially when allergy is possible. [5]

What can an appointment make clear?

An appointment can review the concern, past results and the question that needs a further health review. Ask what the practice can assess directly and what requires an allergy specialist or dietitian. Do not infer that each test set out on an educational page is offered on site or part of the appointment.

The Functional Medicine Testing and Diagnostics page explains the broader testing approach, while Private GP and Holistic Medical Care in London describes the GP appointment route. Before choosing a package, ask if a clinical discussion should come first. Check the fee, what is included and any separate test or review charges. This page does not quote an unverified food-testing bundle price.

If another doctor has already given you an allergy plan, bring it. A new talk should not leave you with conflicting advice about avoidance, emergency treatment or follow-up. Ask who will remain responsible and how new details will be shared with the service that knows your history.

How should results and next steps be explained?

A results discussion should return to the first reaction or symptom pattern. Ask what the finding supports, what it does not show and if another explanation remains possible. You should know if the outcome is a diagnosis, a reason for specialist assessment or a choice not to test further.

If more assessment is advised, make clear who arranges it and what to do while waiting. If dietary changes are planned, ask how nutritional needs, cost and everyday meals will be weighed up. A report should not leave you to build a complex exclusion diet on your own.

Keep copies of the report and agreed plan. If the reason given differs from an earlier commercial result, ask for the reasoning in plain language. The aim is to reach a safer and more useful understanding of the concern, not to defend a given test or to turn each symptom into evidence of food intolerance.

How can I prepare a clear account of a food reaction?

Start with the event itself. Write the date if you know it, what you ate and what happened next. Use your own words. If you cannot recall a detail, leave a gap and say that you are unsure. Do not fill it from a list of symptoms on the test seller's site.

Keep a note of any care you received and bring the report if there is one. If a meal had many parts, say so. You do not have to pick one food as the cause before the visit. That is part of the question you need help to assess.

If you have a test report, bring the full file. A photo of one coloured box may leave out the test name or its units. Put the report's advice in a separate note from what you have in fact done. For example, list foods you have stopped eating and the date you made each change.

Then write the question you want answered. Is it “What caused that reaction?”, “Is this test valid?” or “How can I eat a wider range of foods safely?” These questions may need different kinds of help. It is fine to bring more than one, but put the most pressing first.

You can ask for the next plan in plain words. Who should you see, what records should you take and what advice applies while you wait? Read it back if you are unsure. The aim is a clear next step, not a longer list of foods you feel afraid to eat.