Food Allergy and Intolerance

How do food allergy and intolerance differ?

Food allergy is an immune reaction to a food. Food intolerance is a different problem and does not itself cause anaphylaxis. Anaphylaxis is a severe allergic reaction that can be life-threatening. Some symptoms can overlap, so do not guess that a worrying reaction is only intolerance. Start by describing what happened. A doctor can then decide what needs to be checked and which route is right. [1] [2]

The word sensitivity is less precise. If it appears on a report or in advice, ask what the provider means. Is it a confirmed diagnosis, a description of symptoms or a theory that still needs testing? The label should not obscure the need to work out what happened.

If you are unsure which applies, start with the reaction itself. Describe the food, timing and symptoms. You do not need to know the diagnosis before seeking help. And you should not have to buy a broad panel to make the concern worth talking about.

For this part of the discussion, see how functional medicine testing is selected and interpreted.

For this part of the discussion, see doctor-led functional medicine in London.

Which symptoms need urgent help?

Sudden swelling of the mouth, tongue or throat, serious breathing trouble or collapse can be signs of a severe allergic reaction. Call 999. If emergency adrenaline has been prescribed, use it as directed and call 999 even if symptoms improve afterwards. [1]

Do not wait for a food-testing visit or an online reply during a serious reaction. A past mild reaction does not make a current severe one safe. Tell the emergency service what has happened and follow its instructions.

If the concern is not an emergency but reactions keep occurring, arrange medical review. The purpose is to understand the pattern and decide what investigation or referral is needed. Keep urgent symptoms separate from a longer talk about diet quality or general gut health.

If you already have a written allergy plan, keep it accessible and follow the advice from your allergy team. A new nutrition or functional-medicine plan should not override that plan or encourage you to try a known trigger without specialist direction.

What should a reaction history include?

Write down the food, the amount if you know it and when the symptoms began. Say what happened next and what help or treatment was used. Keep the packet or a photo of the ingredients if useful. You do not need a perfect record. Do not delay urgent care to make notes, and do not eat the food again just to see if the same thing happens.

Also explain if the same food has been eaten without a reaction and if similar symptoms have occurred at other times. These details help the doctor judge the pattern. They are not an instruction to repeat an exposure to see what happens.

Describe symptoms plainly rather than using only a test label. A rash, vomiting, wheeze and bloating are different observations. Say which occurred and in what order, if you know. If your memory is uncertain, say so rather than filling the gaps with assumptions.

Tell the doctor if the reaction followed exercise, alcohol or another medicine as well as food. Record the circumstances without trying the combination again yourself. This context may help the specialist assess the event.

The EAACI diagnostic guideline places an allergy-focused history at the start of review. It then considers targeted tests in context. A test chosen without the history may answer the wrong question or produce a result that is hard to interpret. [3]

Which tests can support suspected food allergy?

Some blood and skin tests can help assess a suspected food allergy. Tests for specific IgE look for an antibody involved in one type of allergic response. The result needs to be read with the story of the reaction. A positive test alone is not the whole diagnosis. Ask why that food is being tested and what the result could change in your care. [3]

The EAACI guideline describes oral food challenge as an important diagnostic tool in suitable clinical settings. This is not a home experiment. If a challenge is needed, the allergy service should explain the setting, preparation and safety arrangements. [3]

Ask why the specific food is being tested and what the result would change. Testing many foods without a focused question can create confusing findings. A clear account should cover both the value of a result and what it cannot show.

The Food Allergy and Food Intolerance Assessment & Testing guide discusses food testing in more detail. Keep the distinction between the test's technical output and the diagnosis. Detecting an antibody does not, on its own, tell you how a person will react to a food or what food plan they should follow.

Why can broad panels and exclusions mislead?

Some tests sold for food reactions are not valid tests for allergy. BSACI includes IgG tests among these. A panel with many positive foods does not prove that those foods caused your symptoms. Ask how the test has been checked for this use. Do not let a long list of flags replace a careful reaction history or become the sole reason to remove many foods. [4]

The NHS also warns that some commercial tests claiming to find intolerance have limited evidence of accuracy. They may lead people to exclude many foods. Before changing your diet on that basis, talk about the result with a GP or an appropriately qualified dietitian. [2]

Ask how nutritional needs will be met if a food is removed. The impact can be greater when several staple foods are excluded or when the advice is for a child. A plan should have a purpose, suitable alternatives and a clear way to review it.

Do not use improvement during a complex programme as proof that every test flag was correct. Several things may have changed at once, and symptoms can vary. The clinical interpretation needs more care than a simple before-and-after story can give.

When is specialist or dietetic input useful?

An allergy service may be needed to work out the diagnosis or make a clear safety plan. A dietitian may help you eat well when a food must be avoided. These roles address different needs. Ask which kind of help fits your situation. A general promise to balance immunity should not replace either the medical review or the work needed to keep your diet safe and adequate.

If food has become frightening or your diet is shrinking, say so. The burden on daily life matters too. It is part of the care you need. Ask for help that takes both safety and adequate nutrition into account, rather than adding more restrictions without a clear reason.

Before booking extra support, ask who will give it and how it will fit with existing allergy care. Bring the reaction history, reports and any written emergency plan. Make clear if you need diagnosis, help with avoidance or a review of advice already given.

The next step should answer the question you need help with. It may be a targeted review, specialist referral or dietetic support rather than another broad test. Ask who will explain the result, who will update the plan and what you should do if another reaction occurs.