Allergy vs Intolerance: What’s the Difference (and How to Get Answers)
- James Murray
- 58 minutes ago
- 5 min read
If you’re dealing with symptoms like bloating, stomach discomfort, skin flare-ups, sinus problems, wheeze, headaches, fatigue, or “brain fog”, it’s completely understandable to wonder: is this an allergy or an intolerance?
The tricky part is that allergies and intolerances can look similar, and symptoms don’t always point clearly in one direction. The good news is you don’t have to figure it out alone. With the right history, testing (when appropriate), and clinical interpretation, most people can get much clearer about what’s going on — and what to do next.
Quick overview: allergy vs intolerance
What is an allergy?
An allergy usually involves the immune system. Symptoms can come on quickly after exposure (minutes to a few hours). Allergic reactions can range from mild to severe.
Common allergy symptoms
hives (urticaria), itching
swelling of lips/face/eyes
wheeze, cough, breathing symptoms
sneezing, watery/itchy eyes, nasal congestion
vomiting or abdominal pain soon after eating a trigger
severe reactions can include anaphylaxis (a medical emergency)
What is an intolerance?
An intolerance usually does not involve the same immediate immune mechanism as an allergy. Symptoms are often delayed and frequently linked to digestion — although some people experience broader symptoms too.
Common intolerance symptoms
bloating, abdominal discomfort, gas
diarrhoea or constipation
nausea or reflux
fatigue, “brain fog”
headaches
symptoms that seem linked to certain foods but aren’t immediate
Why it’s hard to tell the difference
Many symptoms overlap, and there can be more than one factor involved. For example:
bloating can be intolerance, IBS, stress, reflux, infection, medication side effects, or dietary patterns
rashes can be allergy, eczema, contact reactions, viral triggers, heat/sweat, or chronic urticaria
fatigue can be sleep-related, stress-related, deficiency-related, hormonal, or linked to diet
That’s why a good approach is often:
Listen to your story properly (what happens, when, and how often)
Use testing only when it’s likely to help
Make sure results are interpreted in clinical context
When testing can be helpful
Testing can be useful when:
symptoms are consistent and recurring
there’s a clear pattern with certain exposures
symptoms are troubling or affecting quality of life
you want clarity rather than guesswork
there’s concern about risk (especially breathing symptoms or swelling)
Allergy testing (often IgE-based blood testing)
IgE blood tests can help when symptoms suggest immediate-type allergy (such as hives, swelling, wheeze, reactions soon after foods).
Intolerance-focused investigations
Intolerance is often more complex. The most helpful approach is usually:
symptom-led discussion
careful selection of investigations (where appropriate)
practical, safe next steps (not blanket restriction)
Reassurance: If you’ve been going round in circles, that’s very common — and support from a clinician can reduce confusion and speed up the right next step.
Why results need clinical interpretation (and why people can feel stuck)
One of the biggest frustrations patients report is:“I got results, but I don’t know what they mean.”
That can happen because:
some results indicate sensitisation, not necessarily a true clinical allergy
some symptoms don’t match the pattern of the results
people may change their diet too dramatically and feel worse
there may be another underlying cause that needs attention
A clinician-led pathway helps turn “information” into a clear plan.
How YPC Health helps (patient-centred, clinician-led)
At YPC Health, our focus is patient-centred care:
we listen carefully to your symptoms and goals
we help you choose the most appropriate option
we explain results clearly and calmly
we provide safety-netting and guidance
we can arrange prescriptions and referrals when clinically appropriate
and you can speak to a real human GP — not an automated or AI response
If you already had tests elsewhere and feel unsure what they mean, we can also offer a GP appointment to review and interpret your results and discuss next steps.
When to seek urgent help
If you develop:
swelling of lips/tongue/throat
difficulty breathing or wheeze
collapse or severe dizziness
a severe reaction after eating or exposure
Seek urgent medical attention via 111 or 999 (in the UK)
Speak to us (no-obligation advice)
Because there are many types of allergy and intolerance, we recommend speaking to us so we can guide you to the most appropriate option.
Call: 0113 531 4947
Email: info@ypchealth.co.uk
FAQs: Allergy Blood Tests (IgE) Explained
1) What is a specific IgE allergy blood test?
A specific IgE blood test measures IgE antibodies to individual allergens (such as certain foods, pollens, dust mites, or animal dander). It can support the assessment of suspected allergy when interpreted alongside your symptoms and medical history.
2) What does a “positive” IgE result mean?
A positive result often means sensitisation (your immune system recognises the allergen). It does not automatically confirm a true clinical allergy. A clinician will interpret whether the result matches your symptoms and exposure history.
3) Does a higher IgE level mean a more severe allergy?
Not reliably. IgE levels can sometimes suggest the likelihood of allergy for certain allergens, but they do not predict severity. Severity is more closely linked to your reaction history and other factors such as asthma control and co-factors (exercise, alcohol, illness).
4) What does a “negative” IgE result mean — can I still have symptoms?
Yes. A negative result can be reassuring, but symptoms may relate to a different allergen, a non-IgE mechanism, an intolerance, or another condition altogether. A GP review helps decide whether further assessment is needed.
5) Why do my results not match how I feel?
This is common. Some people have positive results but no symptoms (sensitised but not clinically allergic), and some people have symptoms from a different cause. Results also depend on what was included in the test panel. A clinician can help identify what’s relevant and what isn’t.
6) Should I stop eating foods that show as “positive” on my report?
Not automatically. Avoiding foods unnecessarily can lead to over-restriction, anxiety, and nutritional issues. If you’ve had severe reactions (swelling, breathing difficulty, collapse), seek urgent medical advice. Otherwise, speak to a clinician first for safe, personalised guidance.
7) Can IgE tests diagnose food intolerance?
IgE tests are mainly used for allergy, not intolerance. Food intolerance often involves different mechanisms and can cause delayed symptoms. If your symptoms suggest intolerance, a GP can advise which investigations (if any) are appropriate and what practical next steps to take.
8) Can YPC Health help if I had my test done elsewhere?
Yes. If you’ve used a “test-only” service and you’re unsure what your report means, you can book a consultation with a real, GMC-registered GP at YPC Health for interpretation, reassurance, and a clear plan for next steps.
9) What happens after testing with YPC Health?
We offer a clinician-led approach. Testing can include phlebotomy (where required), lab processing, and then a GP follow-up to explain results clearly and advise next steps. Follow-up can be face-to-face, video, telephone, or written (email/letter).
10) When should I seek urgent help for possible allergy symptoms?
Seek urgent medical attention if you develop swelling of the lips/tongue/throat, difficulty breathing or wheeze, collapse/severe dizziness, or a severe reaction after eating or exposure. If you’re unsure, it’s always safer to get urgent advice.
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