If you've been searching for a way to understand your symptoms — bloating, fatigue, skin flare-ups, headaches — you've probably come across three very different types of test: hair testing, IgG blood testing, and IgE blood testing. They're often talked about as if they're interchangeable. They're not.
Each one uses a different sample, measures something different in your body, and is designed to answer a different question. Choosing the wrong one for what you're actually trying to find out is the most common reason people feel let down by a test's results. This guide breaks down exactly how each method works, what the evidence says, and which one is likely to suit your situation.
Quick answer: if you suspect a classic allergy (reactions that happen within minutes and could be serious), start with an IgE blood test and speak to your GP. If you're exploring possible food intolerances behind ongoing digestive or energy-related symptoms, an IgG blood test is the more established starting point. If you want a broad, affordable, non-invasive overview to help focus your thinking before going further, a hair (bioresonance) test is designed for that.
The three methods at a glance
| IgE Blood Test (Clinical Testing) |
IgG Blood Test (Laboratory Testing) |
Hair Sample Test (Wellness Screening) |
|
|---|---|---|---|
| Sample type | Finger-prick blood sample | Finger-prick blood sample | A few strands of hair |
| What it measures | Specific IgE antibodies linked to allergic reactions | Specific IgG antibodies associated with delayed food reactions | Bioresonance frequency responses to a wide panel of items |
| Category | Clinically recognised diagnostic marker | Laboratory blood analysis | Complementary and Alternative Medicine (CAM) wellness screen |
| Best suited to | Investigating suspected allergies; supporting a medical assessment | Exploring possible food-related patterns behind digestive/energy symptoms | A broad, low-cost starting point before deciding where to look further |
| Typical turnaround | 3–7 days | 3–7 days | 3–5 days |
| Price tier | ££–£££ | ££–£££ | £–££ |
| NHS-recognised? | Yes — the same antibody class used in clinical allergy testing | Not currently used in NHS diagnostic pathways | Not currently used in NHS diagnostic pathways |
IgE blood testing: clinical allergy testing
What it is: a laboratory blood test that measures IgE (immunoglobulin E) antibodies — the specific antibody class the body produces during a true allergic reaction.
What it looks at: your immune system's antibody response to specific allergens — foods, pollen, pet dander, dust mites and similar. A raised IgE level to a particular allergen indicates your immune system has been sensitised to it.
Why it's different from the other two: IgE testing sits within mainstream clinical allergy practice. It's the type of testing a GP or allergist would use to support a diagnosis, because true allergic reactions — which can range from mild to severe, including anaphylaxis — are driven by this specific antibody pathway.
Best for:
- Investigating a suspected allergy, particularly where reactions happen quickly after exposure
- Supporting a wider medical assessment alongside your GP or allergist
- Anyone who wants testing grounded in clinically recognised methodology
Worth knowing: if you suspect a serious or rapid-onset allergy, this should always sit alongside — not instead of — professional medical advice. Some medications (antihistamines, steroids, immunosuppressants) can affect IgE results, so it's worth speaking to your doctor before testing if you're taking any of these.
IgG blood testing: exploring food-related patterns
What it is: a laboratory blood test that measures IgG (immunoglobulin G) antibodies produced in response to specific foods.
What it looks at: your levels of food-specific IgG antibodies across a panel of common food and drink items — typically run across all four IgG subtypes (IgG1–4) for the fullest picture.
Why it's different from IgE: IgG antibodies aren't the ones responsible for classic, fast-onset allergic reactions. Elevated food-specific IgG is thought by some practitioners to reflect delayed sensitivities that may play a role in ongoing digestive or energy-related symptoms — though it's worth being clear that IgG testing for food intolerance isn't currently part of NHS diagnostic pathways, and its clinical significance is still debated within mainstream medicine. Many people use it as a practical tool alongside a structured elimination diet, rather than as a stand-alone diagnosis.
Best for:
- Exploring whether specific foods might be connected to ongoing symptoms like bloating, fatigue, or skin issues
- Supporting a structured elimination-and-reintroduction approach
- Anyone who's already ruled out (or is separately investigating) a true allergy and wants to look at delayed food-related patterns instead
Worth knowing: most medications don't meaningfully affect IgG results, though long-term immunosuppressive therapy or steroid use may reduce antibody levels.
Hair (bioresonance) testing: a broad wellness screen
What it is: a non-invasive wellness screening method that analyses a small hair sample against a wide panel of food, drink and environmental items.
What it looks at: bioresonance testing is categorised as a Complementary and Alternative Medicine (CAM) approach. It's designed to highlight response patterns across a broad range of items — often 1,000+ — to give a wide overview rather than a targeted clinical result.
Why it's different from the blood tests: hair testing doesn't measure immune antibodies at all, so it isn't directly comparable to IgE or IgG testing on a scientific basis, and it isn't used in NHS diagnostics. What it does offer is a low-cost, pain-free, needle-free way to get a broad starting point — many people use it as a first step to help decide where a more targeted blood test might be worth focusing next, rather than as a replacement for one.
Best for:
- Getting a wide, affordable overview across a large number of items in one go
- People who want to avoid blood samples or needles entirely
- Using as a starting point to help focus where to look further, rather than a final answer
Worth knowing: because bioresonance doesn't measure immune antibodies, it won't necessarily reflect a confirmed allergy — always continue to avoid any allergen identified by a medical professional, regardless of your hair test results.
Which test suits your situation?
| If you're experiencing… | The best starting point is usually… |
|---|---|
| Rapid-onset symptoms after eating — swelling, hives, breathing difficulty | IgE blood test, and speak to your GP promptly |
| Ongoing bloating, fatigue, headaches or skin issues with no obvious trigger | IgG blood test, ideally paired with an elimination diet |
| Wanting a wide-ranging overview before narrowing things down | Hair (bioresonance) test |
| A needle-free, budget-friendly first step | Hair (bioresonance) test |
| Wanting the most clinically established option available | IgE or IgG blood test, depending on the type of reaction suspected |
Frequently asked questions
Can I take more than one type of test?
Yes — many customers use a hair test as a broad first step, then follow up with a targeted IgG or IgE blood test on specific items that stood out. The three methods aren't mutually exclusive; they answer different questions.
Is IgG testing the same as an allergy test?
No. Allergy testing measures IgE antibodies and relates to the body's immediate immune response. IgG testing looks at a different antibody entirely and is associated with delayed food-related patterns rather than allergic reactions.
Is hair testing scientifically proven?
Bioresonance hair testing is categorised as a Complementary and Alternative Medicine approach and isn't used in NHS diagnostics or considered a medical diagnostic tool. It's offered as an informational wellness screen, not a substitute for clinical testing or professional medical advice.
Do I need a GP referral for any of these?
No — all three can be taken as at-home tests without a referral. That said, if you suspect a serious or rapid-onset allergy, you should speak to your GP or allergist regardless of which test you take.
Which test is most accurate?
"Accuracy" depends on what you're trying to measure. IgE testing is the clinically recognised standard for allergy investigation. IgG testing is a laboratory blood analysis with an active but still-debated evidence base for food intolerance. Hair testing is a wellness screening tool designed for breadth rather than clinical diagnosis. None of the three replaces professional medical advice.
Tests and related information provided on this page do not make a medical diagnosis and are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your doctor or other qualified health provider if you have a medical condition or symptoms that concern you.
