Chronic Hives (Urticaria): Is an Undiagnosed Allergy the Hidden Cause?

Published: 28 February 2026 · Medically reviewed content · Written for UK patients

Hives — known medically as urticaria — are one of the most common skin presentations seen by GPs and dermatologists in the UK. The typical hives symptoms are hard to mistake: raised, itchy welts that appear suddenly, change shape, and may vanish within hours only to reappear elsewhere. For many people the episode is brief and self-limiting. For others, it becomes a recurring, exhausting pattern that disrupts sleep, concentration, and daily life.

When hives persist for six weeks or longer, the condition is classified as chronic urticaria. At this point, a natural question surfaces: could an undiagnosed allergy be behind this? The answer is nuanced. In some cases an IgE-mediated allergy does play a role — but in many cases of chronic urticaria, particularly spontaneous hives with no clear external trigger, the mechanism is quite different.

This guide explains the distinction, outlines when allergy blood testing may genuinely help, and offers a pragmatic pathway you can discuss with your GP or specialist.

Acute vs Chronic Hives: What ‘Chronic’ Really Means

In clinical practice, urticaria is divided into two broad categories based on duration:

• Acute urticaria — episodes lasting fewer than six weeks. These are often triggered by a viral infection (especially in children), an allergic reaction to food or medication, or an insect sting. The trigger is frequently identifiable.
• Chronic urticaria — hives that recur on most days for six weeks or longer. This is further subdivided into chronic spontaneous urticaria (CSU), where welts appear without a clear external trigger, and chronic inducible urticaria, where hives are provoked by a specific physical stimulus such as pressure, cold, heat, or vibration.

According to NHS guidance, chronic spontaneous urticaria is the most common form of chronic hives and affects roughly 0.5–1% of the UK population at any given time. It tends to follow a relapsing and remitting course, and many people find that the condition eventually resolves on its own — although this can take months or, in some cases, several years.

The important point is that ‘chronic’ does not automatically mean ‘allergic’. Understanding this distinction is the first step towards an appropriate assessment.

Common Causes of Chronic Urticaria — and Why Allergy Tests Are Often Negative

One of the most frustrating aspects of chronic urticaria UK patients report is that extensive allergy testing often comes back negative. This is not a failure of the tests — it reflects the underlying biology of the condition.

Autoimmune Mechanisms

A significant proportion of CSU cases are thought to have an autoimmune basis. In these patients, the immune system produces autoantibodies (typically IgG antibodies against IgE or the high-affinity IgE receptor FcεRI on mast cells) that directly activate mast cells in the skin, causing histamine release and hive formation — without any external allergen being involved. This is sometimes referred to as chronic autoimmune urticaria and may account for 30–50% of CSU cases, according to BSACI guidelines.

Infections and Inflammatory Conditions

Chronic infections — including Helicobacter pylori, dental abscesses, urinary tract infections, and chronic sinusitis — have been associated with urticaria in some studies, though the evidence for a direct causal link is mixed. Resolving the underlying infection sometimes leads to improvement in hives, but this is not guaranteed.

Physical and Environmental Triggers

In chronic inducible urticaria, hives are provoked by specific physical stimuli. Common types include:

• Dermatographism — hives appearing along lines of pressure or scratching on the skin
• Cold urticaria — hives triggered by exposure to cold air, water, or surfaces
• Cholinergic urticaria — small, itchy welts triggered by sweating, exercise, or heat
• Delayed pressure urticaria — deeper swelling occurring hours after sustained pressure (e.g., from a bag strap or waistband)

Stress and Chronic Urticaria

The relationship between stress vs allergy is a question many patients raise. Psychological stress does not cause urticaria in the same way an allergen triggers an IgE reaction. However, stress is widely recognised as a modifying factor that can worsen the frequency and severity of existing hives. This is likely related to the way stress hormones (particularly cortisol and corticotropin-releasing hormone) interact with mast cell activity. Managing stress may not eliminate hives, but it can form a useful part of a broader management plan.

When Allergy Can Be Relevant to Chronic Hives

While allergy is not the primary driver of most chronic spontaneous urticaria, there are clinical scenarios where an IgE-mediated mechanism may genuinely be at play:

Clear Immediate Food-Trigger Pattern

If you consistently develop an itchy skin rash or hives within minutes to two hours of eating a specific food — particularly peanuts, tree nuts, shellfish, cow's milk, eggs, wheat, soy, or fish — this pattern suggests a possible IgE-mediated food allergy. In these cases, specific IgE blood testing for the suspected food can provide useful information.

Latex Allergy

Occupational or domestic latex exposure can cause contact urticaria (hives at the site of contact) and, in more severe cases, generalised hives or anaphylaxis. Healthcare workers, cleaners, and laboratory staff are at higher risk. Latex-specific IgE testing is available and may be appropriate if the clinical history suggests latex contact is involved.

Medication-Related Triggers

Certain medications — most notably non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and aspirin — can worsen or trigger hives in a significant minority of people with chronic urticaria. This is typically a pharmacological (non-IgE) effect rather than a true allergy, but it is important to identify because avoiding these medications may substantially reduce flare frequency. Antibiotics (particularly penicillins) can also cause IgE-mediated urticaria, though less commonly than is often assumed.

Environmental Allergens

In some cases, particularly in people with an atopic background (a personal or family history of eczema, asthma, or hay fever), environmental allergens such as house dust mites, pet dander, or mould may contribute to urticarial flares. The evidence for environmental allergens as a primary cause of chronic hives is limited, but testing may be worthwhile if there is a clear temporal pattern suggesting exposure-related worsening.

A Pragmatic Assessment Pathway

If you are experiencing recurrent hives, the following steps can help you and your clinician work towards a clearer picture:

1. Track Your Symptoms

Keep a simple symptom diary for at least two to four weeks. Record:

• When hives appear (time of day, day of week)
• Where on the body they occur
• How long individual welts last (a single welt lasting more than 24 hours may suggest a different condition, such as urticarial vasculitis, and warrants medical review)
• Any associated angioedema (deeper swelling of the lips, eyes, hands, or feet)
• Possible triggers — foods eaten in the preceding two hours, physical activity, temperature changes, stress levels, new products or medications

Photographs are extremely helpful for your GP, as hives are often transient and may have resolved by the time of your appointment.

2. Review Your Medications

Make a list of all medications, supplements, and over-the-counter remedies you take regularly. Pay particular attention to NSAIDs (ibuprofen, aspirin, naproxen), which are known to aggravate urticaria in susceptible individuals. ACE inhibitors (used for blood pressure) can cause angioedema and should also be flagged.

3. Consider Your Atopic History

If you have a personal or family history of eczema, asthma, or allergic rhinitis, you may be more likely to have an IgE-mediated component to your hives. This information helps your clinician decide whether targeted allergy testing is appropriate.

4. Seek a GP Review

Your GP can assess whether your hives are likely to be spontaneous (no clear external trigger) or inducible (triggered by a specific physical stimulus), review your medication history, and arrange baseline blood tests if appropriate. If hives are not controlled with standard antihistamine therapy, your GP can refer you to a dermatologist or allergy specialist for further assessment.

Testing: Where IgE Blood Tests May Help

IgE blood tests — also known as specific IgE or ImmunoCAP tests — measure the level of IgE antibodies your immune system has produced against a particular allergen. Results are reported in kU/L (kilounits per litre), with higher levels generally indicating stronger sensitisation.

When Testing Is Most Useful

Allergy blood testing is most informative when it is guided by your clinical history — that is, when there is a specific suspect trigger based on the pattern of your symptoms. Indiscriminate testing (ordering large panels of allergens without a clinical rationale) can produce confusing results, including false positives due to cross-reactivity, and is generally not recommended by BSACI or NICE for the routine investigation of chronic urticaria.

Scenarios where targeted IgE testing may add value include:

• A consistent pattern of hives appearing shortly after eating a specific food
• Suspected occupational allergen exposure (e.g., latex, wheat flour in bakers)
• A history of hives or angioedema in association with insect stings
• Confirming or ruling out sensitisation to a specific environmental allergen in someone with a clear exposure pattern

At Allergy Clinic, we offer specific IgE blood tests for individual allergens, multi-allergen profiles, and comprehensive panels including the ALEX² test, which screens for over 300 allergens from a single blood sample. We also offer a Histamine Releasing Urticaria Test and a Histamine (Urine) test, which may be relevant in specific clinical contexts — for example, as part of a specialist investigation into mast cell activity. All tests involve nurse-led venepuncture and produce a detailed laboratory report.

Interpreting Your Results

A positive specific IgE result indicates sensitisation — the presence of IgE antibodies against that allergen. It does not automatically confirm that the allergen is causing your hives. Clinical correlation is essential: your GP, allergist, or immunologist will consider the test results alongside your symptom history, trigger patterns, and overall clinical picture before recommending any changes.

Similarly, a negative result can be helpful — it makes it less likely (though not impossible) that a particular allergen is driving your symptoms, which can help narrow the focus of further investigation.

Management Discussion Points to Take to Your Clinician

The following is not prescriptive medical advice but a summary of the management approaches that are commonly discussed in UK clinical practice for chronic urticaria. Any treatment decisions should be made in partnership with your doctor.

Antihistamines: The First-Line Approach

Second-generation (non-sedating) antihistamines — such as cetirizine, loratadine, and fexofenadine — are the cornerstone of chronic urticaria management, according to both NICE and BSACI guidelines. They work by blocking the histamine H1 receptor, reducing the itch and wheal response. Key points to discuss with your clinician:

• Regular dosing — taking antihistamines daily (rather than only when hives appear) tends to be more effective for chronic urticaria. You can read more about how long antihistamines take to work in our related guide.
• Updosing — BSACI guidelines allow for second-generation antihistamines to be prescribed at up to four times the standard licensed dose for chronic urticaria, under medical supervision. This step is often tried before moving to second-line treatments.
• Sedating antihistamines — older antihistamines such as chlorphenamine or hydroxyzine may be used as short-term add-ons, particularly at night, but are not generally recommended for long-term daily use due to their sedative effects.

Beyond Antihistamines: Escalation Options

If high-dose antihistamines do not adequately control your symptoms, your specialist may discuss the following options:

• Omalizumab (Xolair) — a biologic injection that targets free IgE and is licensed for chronic spontaneous urticaria that does not respond to antihistamines. It is available through NHS specialist centres.
• Short courses of oral corticosteroids — may be used for severe flares, but are not appropriate for long-term management due to side effects.
• Immunosuppressants — such as ciclosporin, may be considered in specialist settings for refractory cases.

When to Request a Specialist Referral

Consider asking your GP about referral to a dermatologist or allergy/immunology specialist if:

• Your hives have persisted for six weeks or longer
• Standard antihistamine treatment is not controlling your symptoms
• You experience recurrent angioedema (deeper swelling) — learn more about how long hive rashes typically last
• Individual welts last longer than 24 hours or leave bruising (this may suggest urticarial vasculitis)
• You have experienced features of anaphylaxis alongside your hives

Questions to Ask After You Receive Your Test Report

If you have had allergy blood tests, the following questions may help you and your clinician make the most of the results:

• Which allergens showed a positive IgE result, and at what level?
• Does my clinical history match the sensitisation pattern identified by the tests?
• Should I avoid any specific triggers based on these results, or is further investigation (e.g., supervised food challenge) needed?
• Are any of the positive results likely to reflect cross-reactivity rather than a true clinical allergy?
• Based on these results, is referral to a specialist appropriate?

Frequently Asked Questions

What are the most common hives symptoms?

The most common hives symptoms include raised, itchy welts (wheals) on the skin that are often pale pink or red, surrounded by a flare of redness. They can appear anywhere on the body, change shape, and typically resolve within 24 hours — though new welts may continue to appear. Some people also experience deeper swelling beneath the skin (angioedema), particularly around the eyes, lips, hands, or feet.

How long do chronic hives last?

By definition, chronic urticaria involves hives that recur on most days for six weeks or longer. Some cases persist for months or even years. According to BSACI and NHS guidance, many cases of chronic spontaneous urticaria eventually resolve on their own, but the timeline varies widely from person to person. Read more about whether urticaria can be permanently cured.

Can stress cause hives?

Stress does not directly cause hives in the same way that an allergen triggers an IgE-mediated reaction. However, psychological stress is widely recognised as a factor that can worsen or prolong existing urticaria. This is thought to be related to the way stress hormones interact with mast cells. If you notice that your hives are more frequent during stressful periods, it is worth mentioning this to your GP or specialist as part of your overall assessment.

Should I get an allergy blood test for my chronic hives?

If your hives consistently appear within minutes to a few hours of eating a particular food or after exposure to a specific environmental trigger, a specific IgE blood test may help identify or rule out sensitisation to that allergen. However, in most cases of chronic urticaria UK clinicians see, routine allergy blood panels are not recommended as a first-line investigation because the cause is often autoimmune or idiopathic rather than IgE-mediated. Testing is most useful when guided by your clinical history.

What is the difference between acute and chronic urticaria?

Acute urticaria lasts less than six weeks and often has a clear trigger, such as a viral infection, an allergic reaction to food, medication, or an insect sting. Chronic urticaria lasts six weeks or longer and frequently has no single identifiable cause — it is often classified as chronic spontaneous urticaria (CSU). The two forms can overlap, and some people initially develop acute hives that then transition into a chronic pattern.

Are antihistamines safe to take long-term for hives?

Second-generation (non-drowsy) antihistamines such as cetirizine, loratadine, and fexofenadine are generally considered safe for long-term daily use, according to NICE and BSACI guidance. They are the first-line treatment for chronic urticaria. If standard doses are insufficient, specialists may recommend higher doses (up to four times the standard dose) under medical supervision. Any change to dosing should be discussed with your doctor or pharmacist.

Can chronic urticaria be autoimmune?

Yes. A significant proportion of chronic spontaneous urticaria cases are thought to have an autoimmune basis. In some patients, the immune system produces antibodies (IgG autoantibodies) that activate mast cells in the skin, leading to histamine release and hive formation — even without an external allergen trigger. This is sometimes referred to as chronic autoimmune urticaria and may require specialist assessment and treatment.

Can food allergies cause hives?

Yes, IgE-mediated food allergies can cause hives as part of an acute allergic reaction. This typically occurs within minutes to two hours of eating the trigger food. Common culprits include peanuts, tree nuts, cow's milk, eggs, wheat, soy, fish, and shellfish. However, food allergy is an uncommon cause of chronic urticaria. If you suspect a food is triggering your hives, keeping a food and symptom diary can help guide further investigation.

When should I see a specialist about my hives?

You should consider asking your GP for a referral to an allergy specialist or dermatologist if your hives have persisted for six weeks or longer, if antihistamines are not controlling your symptoms adequately, if you experience recurrent angioedema (deeper tissue swelling), or if you have any features that suggest anaphylaxis — such as difficulty breathing, throat swelling, or dizziness alongside your hives.

Do allergy blood tests diagnose urticaria?

No. Allergy blood tests (specific IgE tests) do not diagnose urticaria itself. What they can do is identify whether you are sensitised to a particular allergen — for example, a specific food, pollen, or animal dander. A positive result indicates sensitisation (the presence of IgE antibodies) but not necessarily clinical allergy. The results should always be interpreted alongside your symptom history by a qualified clinician such as a GP, allergist, or immunologist.

Considering an Allergy Blood Test?

If your symptom history suggests that a specific allergen may be contributing to your hives, targeted allergy blood testing can provide a useful starting point for further clinical discussion. At Allergy Clinic, we offer nurse-led venepuncture and laboratory-analysed specific IgE testing — from individual allergen tests to comprehensive panels covering over 300 allergens.

Our service provides a diagnostic blood sample and a detailed laboratory report. We recommend taking your results to your GP, allergist, or immunologist for clinical interpretation and personalised guidance.

View available allergy tests and book an appointment →

Sources

• NHS — Urticaria (hives), Allergies overview, Anaphylaxis. Available at: nhs.uk/conditions/hives
• Allergy UK — Factsheets on urticaria, skin allergy, and food allergy. Available at: allergyuk.org
• British Society for Allergy and Clinical Immunology (BSACI) — Guidelines on the management of chronic urticaria and patient resources. Available at: bsaci.org
• NICE — Clinical Knowledge Summaries: Urticaria. Available at: nice.org.uk
• Anaphylaxis UK — Guidance on recognising and managing anaphylaxis. Available at: anaphylaxis.org.uk
• Food Standards Agency — Allergen labelling regulations. Available at: food.gov.uk