Medically reviewed by the medical team at The Wellness. Last reviewed November 2026.
A food allergy is an immune reaction that can cause hives, swelling, vomiting or breathing difficulty within minutes, while a food intolerance causes slower, uncomfortable but not dangerous symptoms such as bloating. Validated allergy tests are specific IgE blood tests, skin prick tests and supervised food challenges. IgG intolerance tests are not recommended. The Online GP by The Wellness offers doctor-led allergy screens from £395.
Key points
Around 6% of UK adults, about 2.4 million people, have a clinically confirmed food allergy, according to the Food Standards Agency.
Over 30% of adults in the same study reported reactions to food, so many suspected allergies are something else.
Specific IgE blood tests, skin prick tests and supervised food challenges are the validated ways to diagnose food allergy.
IgG antibodies to food are found in healthy people, so IgG intolerance tests do not diagnose allergy or intolerance.
The Online GP by The Wellness offers a Foundation Screen from £395, a Comprehensive Screen from £695 and a Precision Molecular Profile from £1,495.
What is the difference between a food allergy and an intolerance?
A food allergy is a reaction of the immune system, usually within minutes, that can cause itching, hives, swelling of the lips or tongue, vomiting, wheeze or, in severe cases, anaphylaxis. A food intolerance does not involve the same immune response and causes slower symptoms such as bloating, wind or loose stools.
The difference matters because a true allergy can be dangerous and may need an adrenaline auto-injector, while an intolerance is managed by adjusting how much of a food you eat.
How common are food allergies in adults?
About 6% of UK adults have a clinically confirmed food allergy. The Food Standards Agency’s 2024 adult food allergy study found that peanuts and tree nuts were the most common, along with fruits such as apple, peach and kiwi linked to birch pollen allergy.
The same study found that over 30% of adults reported reactions to food. Many of those reactions are intolerances, pollen-food syndrome or other conditions, which is why testing should follow a careful history.
Ask a doctor on WhatsApp about a reaction to food.
Which allergy tests actually work?
The allergy tests that work are specific IgE blood tests, skin prick tests and, where needed, a supervised oral food challenge. Each is interpreted alongside a detailed history of what you ate, what happened and how quickly.
IgG food intolerance tests sold online are not recommended. A Choosing Wisely summary on alternative allergy tests notes that IgG antibodies to food are found in healthy people and do not indicate allergy or intolerance. Kinesiology and hair analysis have no diagnostic value.
An allergy test only means something next to the story of what happened. A long list of positive results without that history leads people to cut out foods they never needed to avoid.
Who should have an allergy test?
An allergy test suits anyone who has reacted to a food within minutes, anyone with suspected pollen-food syndrome, people with hay fever or eczema who want to know their triggers, and adults deciding whether they need an adrenaline auto-injector.
If your symptoms are mainly bloating or a change in bowel habit, a gut-focused assessment may help more. Our guide to what a full private blood test should include covers the markers that rule out other causes, such as anaemia and thyroid problems.
Ask a doctor on WhatsApp which allergy test suits you.
What happens when I book a doctor-led allergy screen?
A doctor-led allergy screen at The Online GP by The Wellness starts with your history, continues with the tests that fit your symptoms, and ends with a doctor explaining which foods or triggers matter and what to do next.
Message the team on WhatsApp with what you reacted to, your symptoms and how quickly they started.
A doctor takes a detailed allergy history and recommends the screen that fits.
You have the tests the doctor has chosen.
A GMC-registered doctor reviews every result against your history.
You receive a clear explanation and a plan, including an emergency plan or specialist referral where needed.
Tested on evidence. Explained in full.
How much does a private allergy test cost in London?
Allergy testing at The Online GP by The Wellness starts with the Foundation Screen from £395. The Comprehensive Screen costs from £695, and the Precision Molecular Profile costs from £1,495.
Most adults with one or two suspected triggers start with the Foundation Screen. The Comprehensive Screen suits people with several triggers, and the Precision Molecular Profile suits complex or severe reactions. Book an allergy screen on WhatsApp.
Can a doctor tell me whether I need an allergy test?
Yes. Send what you reacted to, your symptoms and how quickly they started on WhatsApp. A doctor tells you which test fits, or whether your symptoms point to something other than allergy.
Start your free suitability review on WhatsApp.
Frequently asked questions
Can you develop a food allergy as an adult?
Yes. Adults can develop new food allergies, and pollen-food syndrome, where raw fruits cause an itchy mouth, often starts in adulthood in people with hay fever.
Are home food intolerance tests accurate?
Home IgG intolerance tests are not recommended. IgG antibodies to food are found in healthy people and do not show that a food is causing your symptoms.
Do I need to stop antihistamines before an allergy test?
Antihistamines affect skin prick tests but not blood tests. The team confirms any preparation when you book.
What should I do if I have a severe reaction to food?
Call 999 if you have swelling of the throat or tongue, difficulty breathing, or feel faint after eating. Use an adrenaline auto-injector if you have been prescribed one.
Sources
Food Standards Agency, Patterns and Prevalence of Adult Food Allergy, 2024
Choosing Wisely, Alternative tests for allergy
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