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Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Assessment online. A doctor can take the history that decides which test you need and explain your results; the tests themselves are done in person.
- Tests that work: skin prick tests, blood tests for specific IgE, patch tests, and supervised food or drug challenges; antihistamines are usually stopped for up to 10 days before a skin prick test.
- Tests that do not: IgG food intolerance tests, Vega or electrodermal tests, kinesiology, hair analysis and pulse tests.
- Key point: a positive test on its own does not prove an allergy: it has to fit your symptoms.
- Emergency: call 112 for swelling of the throat or tongue, difficulty breathing, or feeling faint.
Do not book a video appointment if your lips, mouth, throat or tongue suddenly swell, you are struggling to breathe or swallow, or you feel faint, confused or drowsy. This can be anaphylaxis: use an adrenaline auto-injector if you have one and call 112.
Can an online doctor help with allergy testing?
Yes, with the most important part. The history of your symptoms decides whether you need a test at all, which test, and how to read the result, and a doctor can take it by video. The doctor explains results you already have, treats your symptoms in the meantime, and arranges a referral for the right test. Skin prick, blood, patch and challenge tests are done in person, at a clinic or laboratory.
How an online consultation helps with allergy testing
- Whether you need a test: Many allergies, such as typical hay fever, are diagnosed from the symptoms alone.
- The right test: Skin prick, blood, patch or challenge, depending on the kind of reaction.
- Results explained: What a positive or negative result means for you, and what it does not mean.
- Money not wasted: Which tests sold online or on the high street have no scientific basis.
What the doctor checks in an online consultation before allergy testing
The doctor asks about your symptoms and their pattern, because the test is only as useful as the question it answers. The doctor asks about:
- The reactions: what happened, how quickly, how long it lasted, and how severe it was.
- The suspected triggers: foods, pollen, animals, dust, medicines, stings, or something touching the skin.
- Warning signs: any throat swelling, breathing difficulty or faintness, now or in the past.
- Your skin: eczema or psoriasis, which can make skin tests unreliable.
- Your medicines: antihistamines and others that can interfere with skin tests.
- Tests you have had: including any bought online, and their results.
How do doctors test for allergies?
They start with your history, then use the test that fits: skin prick tests or blood tests for immediate allergies, patch tests for delayed skin reactions, and supervised challenges when the results are unclear. A positive skin or blood test has to fit your symptoms to mean an allergy.
Swipe sideways to compare →
| Test | What it is for | How it is done |
|---|---|---|
| Skin prick test | Immediate allergies to pollen, mould, pet dander, dust mites and foods | Drops of allergen pricked into the skin of the arm, up to 50 at a time, read after about a quarter of an hour |
| Blood test for specific IgE | Immediate allergies, when skin tests cannot be done | A blood sample sent to a laboratory |
| Component blood tests | Telling a true nut allergy from a pollen-related reaction | A blood test for individual allergen proteins |
| Intradermal test | Insect venom and penicillin allergy | A small amount injected into the skin of the arm |
| Patch test | Delayed skin allergies to metals, fragrances, hair dye, latex or medicines | Patches on the skin for 48 hours, with results over several days |
| Food or drug challenge | Confirming or ruling out an allergy when tests are unclear | Increasing amounts given under medical supervision, with emergency equipment ready |
| Cutting out and reintroducing a food | Delayed food allergies and intolerances | Removing the food for a set time, then bringing it back, ideally with a dietitian |
What are the two main types of allergy test?
Skin prick tests and blood tests for specific IgE antibodies. Both look for the immediate, IgE type of allergy, and both are interpreted with your history.
Can a blood test diagnose an allergy?
A blood test can support a diagnosis, but on its own it only shows sensitisation, meaning your body has made antibodies to something. Without your full history, a result is hard to interpret, which is why it has to fit your symptoms.
How do you get an allergy test?
Start with a doctor. A doctor can take your history, arrange some tests, and refer you to a specialist allergy clinic when you need one. In the UK, a GP may arrange tests or refer you to an NHS allergy clinic, so see a GP if you think you have an allergy.
You usually need a specialist referral when:
- you have had a severe reaction or anaphylaxis
- you have reacted to a food, especially nuts, and need to know which foods are safe
- a medicine label, such as penicillin allergy, may be wrong
- the cause of your symptoms is unclear, or your symptoms are severe
Patch tests for contact allergies are usually done by a dermatologist.
Do food intolerance tests work?
No. The food intolerance tests sold online and on the high street, such as IgG blood tests, hair analysis and Vega tests, have no scientific basis for diagnosing allergy or intolerance. They can lead to unnecessary, restrictive diets and miss a real allergy.
Swipe sideways to compare →
| Test | Why it does not work |
|---|---|
| IgG or IgG4 food antibody tests | IgG antibodies to foods are found in healthy people without allergies, so the results are not reliable |
| Vega or electrodermal tests | No scientific evidence that skin conductivity relates to allergy or intolerance |
| Kinesiology | No scientific evidence that it can diagnose food allergies |
| Hair analysis | Unproven, with no scientific basis for allergy testing |
| Pulse test | Heart rate varies with anxiety, stress, activity and hydration |
| Cytotoxic or white cell tests | Results are inconsistent and cannot be reproduced |
The harm is real: unnecessary diets can cause nutritional deficiencies, cost money, and delay the right diagnosis, and a test that misses a real allergy can increase the risk of a serious reaction.
How is a food intolerance really diagnosed?
By cutting the suspected food out for a set time and then reintroducing it while you record your symptoms, ideally with a dietitian. A few conditions do have proper medical tests: a hydrogen breath test for lactose intolerance, and a blood test for coeliac disease, which only works while you are still eating gluten. See lactose intolerance and coeliac disease.
How to prepare for a skin prick test
- Antihistamines: you may be asked to stop them for up to 10 days before, because they block the reaction the test looks for.
- Other medicines: some antidepressants and heartburn medicines interfere too, and omalizumab can affect results for 6 months or more. Do not stop any prescribed medicine without asking the doctor.
- Your skin: widespread eczema or psoriasis on the arms and back can make skin tests unreliable, so a blood test may be used instead.
- Bring a list: of every medicine you take, including ones bought without a prescription.
Is a skin prick test safe?
It is usually just itchy: small, red, raised bumps that fade, and sometimes swelling and itching a few hours later that lasts a couple of days. Rarely, a severe allergic reaction happens, which is why testing is done where emergency equipment and medicines are ready.
What do allergy test results mean?
In a skin prick test, a positive result is a raised, red, itchy bump called a wheal, like a mosquito bite. A larger wheal generally means greater sensitivity, and a negative result means you are probably not allergic to that substance.
Sensitisation is not the same as allergy: a positive skin or blood test means your immune system recognises the substance, but only a matching history, or a challenge, shows that it causes your symptoms. A specialist reads the results with your story, and sometimes confirms them with a supervised challenge.
Which allergy test might the doctor recommend?
The right test depends on the kind of reaction you have had. This is the framework the doctors use:
Swipe sideways to compare →
| What you have | Likely first step | Suitable for online care? | When in-person care is needed |
|---|---|---|---|
| Typical hay fever that settles with treatment | Diagnosis from your symptoms; often no test needed | Yes | Tests if the cause is unclear or treatment fails |
| A reaction to a food, especially nuts | Skin prick, blood or component tests, and a referral | Yes, to assess | Allergy clinic |
| A penicillin allergy label that may be wrong | Grading the risk, then a supervised test dose | Yes, to assess | The test dose |
| An itchy rash where something touched the skin | Patch testing | Yes, to assess | Dermatology clinic |
| Bloating or tummy pain after certain foods | Cutting out and reintroducing foods, a breath test, or a coeliac blood test | Yes, to plan | For the breath or blood test |
| Anaphylaxis, or a severe reaction | A specialist allergy assessment | Partly | Allergy clinic |
Not sure which allergy test you need? A doctor can go through your symptoms and arrange the right one in one consultation.
See available times →Special situations
After anaphylaxis
Anyone who has had anaphylaxis should be referred to an allergy specialist, where testing is done with emergency treatment ready. See anaphylaxis.
Testing at home
Never test a suspected allergy by eating the food or taking the medicine. Blood spot and hair analysis kits sold online are not scientifically proven to diagnose allergy.
Children
Mobi Doctor consultations are for adults aged 18 and over. A child who is unwell needs a paediatrician or a local doctor in person, and emergency signs in a child mean 112.
When allergy testing is assessed online, and when you need in-person care
Assessed online: the history that decides whether you need a test and which one, explaining results you already have, treating symptoms in the meantime, and arranging a referral.
In-person care: skin prick, blood, patch and component tests, supervised food and drug challenges, and the specialist assessment after anaphylaxis.
When to get in-person care
Call 112 or go to an emergency department now for:
- sudden swelling of the lips, mouth, throat or tongue
- breathing very fast or struggling to breathe, or a tight throat
- skin, lips or tongue turning blue, grey or pale
- sudden confusion, drowsiness or dizziness, or fainting
Get medical advice the same day for:
- swelling, itching or a rash a few hours after a skin test that is spreading or getting worse
- hives or swelling after a food or medicine, with normal breathing
How Mobi Doctor works
- Book a time that suits you: daily 7am–11pm CEST. You can see a doctor over video, usually within 15 minutes. No subscription, and the exact price is shown before you pay.
- Speak to a licensed doctor about your symptoms: say what happens, when and after what, and share any test results you already have.
- Leave with a plan: whether you need a test, which one and where, what to do in the meantime, and which signs mean you should be seen in person. If the doctor prescribes, use the prescription at a pharmacy near you.
No sign-up needed
Allergy tests work best when they fit your symptoms. Tick every symptom you have to see each condition page that mentions it. It finds the right page, not a diagnosis: a doctor gives you that on a video call.
Tap the body — an area or a point — to browse symptoms anywhere
Similar symptoms, different condition? Food Allergy can start the same way. Compare them, or look up any other symptom in the full symptom checker.
Frequently asked questions about allergy testing
How do doctors test for allergies?
They start with your history, then use skin prick or blood tests for immediate allergies, patch tests for delayed skin reactions, and supervised challenges when results are unclear.
What symptoms call for allergy testing?
Allergy testing is worth considering when the same symptoms follow the same trigger: hives, swelling, wheeze or sickness soon after a particular food, medicine or sting; year-round sneezing and a blocked nose that could be dust mites or pets; or a rash that keeps appearing where something touches the skin. It is not useful for tiredness, bloating, headaches or weight problems, which allergy tests cannot explain, and anaphylaxis always needs a specialist referral rather than a test alone.
What are the two main types of allergy test?
The two main allergy tests are skin prick tests, in which drops of allergen are placed on the forearm and the skin is pricked and read after about a quarter of an hour, and blood tests for specific IgE antibodies. Both look for immediate allergies, both must be read alongside your symptoms, and patch tests are used instead for delayed contact allergies such as nickel or fragrance.
Can I get an allergy test on the NHS?
Yes. A GP may arrange tests or refer you to an NHS allergy clinic, so see a GP if you think you have an allergy.
Can a GP do allergy testing?
A GP can arrange some tests, such as blood tests, and refers you to a specialist allergy clinic for others, especially after a severe reaction.
Are food intolerance tests accurate?
No. IgG blood tests, Vega tests, kinesiology and hair analysis have no scientific basis for diagnosing food intolerance or allergy, and can lead to unnecessary diets.
How accurate is hair analysis for allergies?
It is not accurate at all: hair analysis has no scientific basis as an allergy test, because allergy antibodies are not measured in hair, and studies have found that the same sample sent to different companies gives different results. The same applies to kinesiology, Vega or electrodermal tests and pulse tests, so money spent on them is wasted and a worrying result from one should be checked with a proper allergy test.
Do I need to stop antihistamines before an allergy test?
Before a skin prick allergy test, usually yes, for up to 10 days, because they block the reaction. Ask the doctor first, and do not stop prescribed medicines without advice.
How long does a skin prick test take?
A skin prick test takes about half an hour in all: the drops are placed and the skin pricked in a few minutes, the skin is read after about a quarter of an hour, and you know the results before you leave. A raised, itchy bump like a mosquito bite at a test site means sensitisation, which the doctor then matches against your symptoms.
Can I prevent a false result from allergy testing?
Mostly, yes: stop antihistamines for up to 10 days before a skin prick test if the doctor agrees, keep taking other prescribed medicines, tell the tester about eczema, dermographism and any recent severe reaction, and do not apply creams to the forearm that day. For a blood test nothing needs stopping. Allergy testing is only as good as the history it is matched to, so bring a note of what happened, when, and how long after the trigger.
What is a patch test?
A test for delayed skin allergies, such as to metals, fragrances or hair dye: patches stay on the skin for 48 hours, and results come over several days.
Can a blood test diagnose an allergy?
A blood test for specific IgE can support a diagnosis of allergy, and it is useful when skin prick testing is not possible, for example with severe eczema or when antihistamines cannot be stopped, but a positive result only shows sensitisation: it has to fit your symptoms to mean an allergy, and many people with a positive test eat the food without any reaction.
Can I test for allergies at home?
No. Never test by eating a food or taking a medicine, and home kits such as blood spot and hair analysis tests are not proven to diagnose allergy.
Can an online doctor help with allergy testing?
Yes, with the part that matters most: the history of your reactions decides whether an allergy test is needed and which one, and a doctor by video can take that history, explain results you already have and arrange the referral. The skin prick tests, blood tests, patch tests and supervised challenges themselves are done in person at a clinic or laboratory.
- Allergies, NHS, National Health Service (UK), reviewed 5 March 2026.
- Food allergy and food intolerance testing, BDA, British Dietetic Association, food fact sheet, August 2026.
- Evidence-based versus non-evidence-based allergy tests and treatments, ASCIA, Australasian Society of Clinical Immunology and Allergy, March 2024.
- Allergy skin tests, Mayo Clinic (US), 26 March 2024.
- Peanut, tree nut and seed allergy, BSACI, British Society for Allergy and Clinical Immunology, accessed 15 October 2026.
- Hair dye reactions, NHS, National Health Service (UK), reviewed 29 December 2025.
- Allergic rhinitis, NHS, National Health Service (UK), reviewed 8 January 2026.
- Lactose intolerance, NHS, National Health Service (UK), reviewed 8 July 2026.
- Coeliac disease: diagnosis, NHS, National Health Service (UK), reviewed 31 March 2023.
- Anaphylaxis: assessment and referral after emergency treatment (NG258), NICE, National Institute for Health and Care Excellence, published 27 May 2026.
- Drug allergy: diagnosis and management (CG183), NICE, National Institute for Health and Care Excellence, published September 2014.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
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