Urticaria (Hives)
Urticaria produces intensely itchy weals that come and go, often without an obvious cause. It is frequently mistaken for an allergy — but in chronic cases, a food or environmental allergen is rarely responsible.
At a glance
- What it is
- Itchy weals caused by the release of histamine and other mediators from mast cells in the skin, sometimes accompanied by deeper swelling (angioedema).
- Who it affects
- Around one in five people experience an episode of acute urticaria at some point. Chronic spontaneous urticaria affects roughly 0.5–2% of the population, and around two-thirds of those affected are women.
- Key feature
- Each individual weal lasts less than 24 hours and fades without a mark — though new ones may appear elsewhere.
- Classification
- Acute if under six weeks. Chronic if weals occur on most days for more than six weeks.
- Treatment
- Regular non-sedating antihistamines first line, with further options if symptoms persist.
What is urticaria?
A weal (or wheal) is a superficial swelling of the skin, usually pale or skin-coloured in the centre with a surrounding red flare. Weals can be a few millimetres or several centimetres across, and may form rings, map-like patterns or large merging patches. They can appear anywhere on the body.
They arise when mast cells in the skin release histamine and other chemical mediators. These widen blood vessels and allow fluid to leak into the surrounding tissue, producing the swelling, while also activating sensory nerves — which is why urticaria itches so intensely.
Angioedema is a related, deeper swelling within the skin or mucous membranes. It often affects the eyelids, lips, hands and feet, and may occur with or without weals.
Types of urticaria
Classification is based on duration and on whether a physical trigger can reproduce the weals. This shapes how the condition is investigated and managed.
| Type | Duration | Typical picture |
|---|---|---|
| Acute urticaria | Under 6 weeks | Often gone within hours to days. In children usually triggered by infection; in adults frequently idiopathic. |
| Chronic spontaneous | Over 6 weeks | Weals appear on most days without a consistent external trigger. An autoimmune basis is likely in around half of cases. |
| Chronic inducible | Over 6 weeks | Reproducibly provoked by a physical stimulus — stroking the skin (dermographism), pressure, cold, heat, exercise, water or sunlight. |
Chronic spontaneous and inducible urticaria commonly co-exist in the same person.
What can provoke or aggravate urticaria
In chronic cases a single cause is often never identified — but several factors are recognised as making weals more likely or more severe.
Infection and immunity
- Viral infections, a very common trigger of acute urticaria in children
- Chronic underlying infections
- Autoimmune conditions including thyroid disease, coeliac disease and vitiligo
- Functional autoantibodies, found in around half of investigated chronic cases
Medication and diet
- Aspirin and non-steroidal anti-inflammatory drugs
- Opiates
- Certain food additives including some colourings and preservatives
- These act as pseudoallergens rather than true allergies
Physical and environmental
- Heat — particularly relevant in Singapore's climate
- Tight or restrictive clothing and pressure from straps or belts
- Firm stroking or scratching of the skin
- Cold, sunlight, water or exercise in inducible forms
How urticaria is treated
The goal is straightforward: complete symptom control, so that the condition stops interfering with sleep, work and daily life. Treatment is stepped up until that is achieved, and later stepped down once the skin has been settled for a period.
First line
Modern second-generation, non-sedating antihistamines are the mainstay. In urticaria they are usually taken regularly rather than only when weals appear, because the aim is to suppress the reaction before it starts. If standard doses are insufficient, guidelines support increasing the dose under medical supervision.
If symptoms persist
Where antihistamines at an appropriate dose do not achieve control, further options exist, including omalizumab, an injectable treatment for chronic spontaneous urticaria. Short courses of oral corticosteroid may be used for severe flares but are not suitable for long-term control. Ciclosporin may be considered in resistant cases under specialist supervision.
Alongside medication
Where an inducible trigger is identified, minimising it helps considerably. Keeping cool, avoiding tight clothing, and noting any relationship to medications such as anti-inflammatories are all practical measures.
When to see a doctor
Arrange an assessment if:
- Weals have been present on most days for more than six weeks
- Itch is disturbing your sleep or affecting daily life
- Over-the-counter antihistamines are not controlling symptoms
- You have recurrent swelling of the lips, eyelids or face
- Individual spots last longer than 24 hours, are painful, or leave bruising
- You suspect a medication may be responsible
Dr Chen Qiping
Consultant Dermatologist · MBBS, MRCP (UK), M.Sc, FAMS (Dermatology)
Dr Chen practises general adult and paediatric dermatology, including urticaria, alongside surgical, laser and cosmetic dermatology. Consultations are available in English and Mandarin.
Urticaria — frequently asked questions
How long do hives last?
Is my urticaria caused by a food allergy?
What is the difference between spontaneous and inducible urticaria?
Are antihistamines safe to take long term?
What causes the swelling of my lips and eyelids?
Will chronic urticaria ever go away?
References
- DermNet. Urticaria — an overview and Chronic urticaria. Author: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand. dermnetnz.org
- Mayo Clinic. Chronic hives — Diagnosis and treatment. mayoclinic.org
- American College of Allergy, Asthma & Immunology. Chronic Spontaneous/Idiopathic Urticaria. acaai.org
Page last reviewed: 28 July 2026.
Persistent hives affecting your daily life?
Arrange a consultation with Dr Chen Qiping at our Collyer Quay clinic — two minutes' walk from Raffles Place MRT.