Heat Urticaria & Cholinergic Urticaria Testing
View All TestsWhat Is Heat Urticaria?
Heat urticaria and cholinergic urticaria are forms of physical urticaria triggered by increases in body temperature. Cholinergic urticaria — the most common type — is triggered by sweating, exercise, hot baths, emotional stress, or spicy food.
Localised heat urticaria (where hives appear specifically where heat is applied) is rarer. Cholinergic urticaria typically presents as many small (2–4mm) itchy wheals across the trunk and arms, appearing within minutes of the trigger and resolving within 30–60 minutes.
Blood tests can help investigate underlying allergic sensitisation and rule out other causes. Clinical diagnosis of cholinergic urticaria may involve exercise provocation testing supervised by a specialist.
Cold Urticaria vs Heat Urticaria
| Feature | Cold Urticaria | Heat / Cholinergic Urticaria |
|---|---|---|
| Trigger | Cold air, water, objects | Heat, sweating, exercise, stress |
| Wheal size | Variable, often large | Typically small (2–4mm), numerous |
| Distribution | Cold-exposed areas | Trunk, arms, widespread |
| Duration | 1–2 hours after rewarming | 30–60 minutes after trigger stops |
How Testing Works
Choose Your Test
Select from our range of allergy blood tests and book a convenient time at our South Kensington clinic. No GP referral needed.
Nurse Blood Draw
A qualified nurse takes a small blood sample at our clinic. The appointment is quick and straightforward.
Get Your Results
Results are sent directly to you, typically within a few working days. Share them with your GP or specialist to guide your next steps.
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Why Choose a Diagnostic-Only Clinic?
Unlike clinics that provide both testing and treatment, our nurse-led service focuses solely on accurate diagnostic testing. Because we don't offer treatments or prescriptions, there is no commercial incentive to recommend unnecessary tests — just honest, impartial results you can trust.
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Our qualified nurses collect your sample — we don't prescribe, treat, or have any reason to upsell.
Results You Own
Your results are sent directly to you. Take them to your GP or a specialist to discuss what's best for your situation.
You Stay in Control
Understand your allergy profile, then decide with your healthcare professional what steps to take next.
Related Reading
Frequently Asked Questions
Can exercise make hives worse?
Yes. Exercise raises core body temperature and induces sweating, both of which are triggers for cholinergic urticaria. Some individuals also experience exercise-induced anaphylaxis, particularly when exercise follows a meal (exercise-induced food-dependent anaphylaxis). If you experience symptoms of anaphylaxis (difficulty breathing, dizziness, swelling of the throat) during or after exercise, call 999 immediately. Discuss these patterns with your specialist.
Is cholinergic urticaria an allergy?
Cholinergic urticaria is a physical urticaria rather than a classic IgE-mediated allergy. It involves mast cell degranulation triggered by cholinergic nerve stimulation during sweating. However, some individuals have an IgE-mediated component to their sweat allergy.
Do I need a GP referral for allergy testing?
No. You can book directly with our clinic without a GP referral. Simply choose your test and select a convenient appointment time. If you're unsure which test is right for your symptoms, our team can help guide your selection.
Do I need to stop taking antihistamines before a blood test?
No. Unlike skin prick testing, IgE blood tests are not affected by antihistamines or other allergy medications. You can continue taking your regular medications before your appointment.
What should I do with my results?
As a diagnostic-only clinic, we provide results directly to you. We recommend sharing them with your GP or dermatologist for interpretation and to discuss management strategies.
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