Allergy or intolerance? Understanding how testing can help.

An itchy mouth after eating, sneezing whenever you visit a friend with a cat, or an upset stomach after certain meals?

When symptoms seem to follow a particular food or exposure, it’s natural to wonder whether an allergy could be responsible. Finding the cause can help you understand what’s happening and make more confident decisions about your health. But allergy testing isn’t simply about testing for as many things as possible. Choosing the right test, and understanding what the results mean for you, matters.

Consultation first, testing second

At The Hove Practice, our starting point is always your symptoms: what happens, when it happens and what seems to trigger it. Where appropriate, we offer allergy assessment for adults and children. Where appropriate, this can include ALEX³ allergy blood testing through The Doctors Laboratory, alongside a GP consultation and personalised written interpretation of your results. 

What is the difference between an allergy and an intolerance?

Allergy and intolerance are sometimes used interchangeably, but they describe different types of reaction. An allergy involves the immune system reacting to something that would normally be harmless, such as a food, pollen, house dust mite or animal dander. Many immediate allergic reactions involve antibodies called IgE. Symptoms can include itching, hives, swelling, vomiting, coughing or wheezing and some allergic reactions can be serious. Other forms of allergy can cause more delayed symptoms and may need a different approach to diagnosis.

A food intolerance does not involve the same allergic immune response. Lactose intolerance, for example, occurs when the body has difficulty digesting lactose, the sugar found in milk. Symptoms can include bloating, wind, abdominal discomfort and diarrhoea, and the amount consumed may sometimes make a difference. Unlike an immediate food allergy, a food intolerance does not cause anaphylaxis.  That distinction is important when considering testing.

What does ALEX³ test for?

ALEX³ is an IgE allergy blood test; it is not a food intolerance test. If digestive symptoms are your main concern, a GP consultation can help establish whether allergy testing, another investigation or a different approach is likely to be more useful.

ALEX³ looks for IgE antibodies associated with a broad range of possible allergens. The current test offered by The Doctors Laboratory includes a panel of 300 allergens, covering common food and environmental sources including nuts and legumes, milk and egg, cereals, seafood, pollens, animal dander, mites, moulds and insect venoms. It also includes many individual molecular allergen components.

That breadth can be useful, but the number of things tested is not what makes the result valuable. What matters is whether the findings help explain the symptoms you have actually experienced.

Why does a GP consultation matter?

Clinical history is a fundamental part of allergy assessment. Before recommending testing, we will want to understand what happens when you experience symptoms, how soon they begin, how long they last and whether the same reaction has occurred more than once. We'll also consider which foods or exposures seem to be involved, what you can eat or encounter comfortably, and any previous significant reactions or relevant medical history. For children, we'll take that history with their parent or carer, taking their symptoms, diet and previous reactions into account.

Both NICE and the British Society for Allergy & Clinical Immunology emphasise that allergy testing should follow an allergy-focused history and that results need to be interpreted in that context.  Sometimes that conversation may suggest that ALEX³ is useful. At other times, a more targeted allergy blood test, another form of investigation or assessment by an allergy specialist may be more appropriate.

Why can the results be more complicated than they appear?

One of the most important things to understand about allergy blood testing is that a positive result does not automatically mean that something causes you symptoms. A positive IgE result may show sensitisation -  meaning your immune system has produced antibodies to a particular substance. But you may still be able to eat or encounter that substance without having an allergic reaction. There can also be cross-reactivity. Someone who is sensitised to pollen, for example, may have positive results to certain foods because some of their proteins are similar.

What can an allergy test tell you?

Used appropriately, allergy blood testing can provide useful evidence to support a diagnosis and help guide practical decisions about managing likely triggers. But there are limitations. That’s why clinical history remains essential and it’s why we don't simply provide you with a laboratory report.

Following ALEX³ testing at The Hove Practice, you'll receive a personalised written assessment explaining the findings that are relevant to you and the recommended next steps. Depending on your history and results, this might include advice about managing likely triggers, further investigation or referral to an allergy specialist.

If your results raise questions about foods you currently tolerate, or about reintroducing a food that has previously caused a reaction, a further GP consultation may be helpful. This will give us time to review the findings alongside your medical history and discuss the safest next steps. We recommend avoiding significant dietary changes or reintroducing a previously reactive food based on the test result alone.

When an allergic reaction is an emergency

It’s important to remember that a severe allergic reaction, or anaphylaxis, is a medical emergency. Sudden swelling affecting the tongue or throat, difficulty breathing, feeling faint or collapsing can all be warning signs.

If you suspect anaphylaxis, use your prescribed adrenaline auto-injector immediately, if you have one, and call 999. Anaphylaxis UK advises calling emergency services immediately after the first dose of adrenaline.

Allergy testing for adults and children at The Hove Practice

If you or your child are experiencing symptoms that you think could be caused by an allergy, the first step is to book a standard GP consultation. We'll talk through what's been happening, consider the most likely triggers and advise whether allergy testing would be helpful.

If you're unsure whether the symptoms you’re encountering suggest an allergy, an intolerance or something else, we're here to help you make sense of what's happening and decide on the most useful next step.

You can contact our helpful Reception Team by email to discuss ALEX³ testing at The Hove Practice, or book your Private GP appointment.

Clinical sources and further information

British Society for Allergy & Clinical Immunology - Investigations in food allergy. Professional information covering clinical history, IgE testing, component-resolved diagnosis and the limitations of allergy testing.

NICE - Food allergy in under 19s: assessment and diagnosis (CG116). UK clinical guidance covering allergy-focused history, testing and interpretation for children and young people.

Allergy UK - Food allergy. Patient information on food allergy, food intolerance, symptoms and diagnosis.

The Doctors Laboratory - ALEX³ Allergy Test. Current laboratory information on the ALEX³ panel and test specification.

Anaphylaxis UK - What to do in an emergency. Patient guidance on recognising and responding to anaphylaxis.

Clinical Review

Clinical information was checked against current NICE and BSACI guidance and information from Allergy UK, Anaphylaxis UK and The Doctors Laboratory at the date of review. This article provides general information and is not a substitute for individual medical advice. Clinically reviewed by: Dr Simon Glew . Originally published: 20 October 2026. Last clinically reviewed: 20 October 2026.