Urticaria (hives) and allergic rashes

Urticaria, commonly known as hives, is a skin reaction that causes raised, itchy patches or welts on the skin. These rashes can appear suddenly, change shape, and move around the body. Urticaria is common and often short lived, but some people experience ongoing or recurrent symptoms.

This page explains what causes urticaria, how it is assessed, and when to seek medical advice.

These articles are intended as educational sources, not diagnostic nor taking place of a proper medical assessment. If you need help with skin concerns, please book an appointment. We also offer specialist GP dermatology input at the Skin Clinic.

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Symptoms of urticaria and hives

Urticaria typically causes:

Raised, itchy welts or patches
Red or skin coloured swelling
Rashes that change location over hours
Symptoms that come and go
Temporary marks that usually fade within 24 hours

Some people also experience swelling of deeper tissues, known as angioedema.

Severe symptoms: seek urgent medical help

Call 999 or seek urgent medical help if you have:

Swelling of the lips, tongue, or throat
Difficulty breathing or swallowing
Dizziness, collapse, or fainting
Rapid spread of swelling or rash with feeling unwell

These symptoms may indicate a severe allergic reaction and require immediate treatment.

Common causes and triggers

Urticaria occurs due to release of histamine and other chemicals in the skin. Common triggers include:

Allergic reactions to foods, medications, or insect stings
Viral or bacterial infections
Physical triggers such as pressure, heat, cold, or exercise
Stress
Unknown causes, particularly in chronic urticaria

In many cases, a specific trigger is never identified.

How a GP assesses urticaria

A GP will usually diagnose urticaria based on symptoms and history. During an assessment, they may ask about:

Timing and duration of the rash
Possible triggers or recent infections
Associated swelling of lips, eyes, or tongue
Medication history
Any breathing or swallowing difficulties

Photographs can be very helpful for remote assessment.

Investigations

Most people with urticaria do not need investigations.

Blood tests or allergy testing may be considered if symptoms are persistent, severe, or suggest an underlying condition.

Self care and management

Simple measures can help reduce symptoms:

Avoid known triggers where possible
Take non drowsy antihistamines as advised
Wear loose fitting clothing
Avoid hot showers during flare ups
Reduce stress where possible

Symptoms often settle within days or weeks.

Medical treatments a GP may recommend

Depending on severity, a GP may recommend:

Regular non sedating antihistamines
Higher dose antihistamines under medical guidance
Short courses of other medication in selected cases

Treatment is tailored to symptom pattern and response.

When to seek GP review

You should consider a GP appointment if:

Hives last longer than 6 weeks
Symptoms are frequent or worsening
Swelling occurs repeatedly
Antihistamines are not controlling symptoms
You want advice on ongoing management

Chronic urticaria can usually be managed with the right treatment plan.