Urticaria

Urticaria is a raised, usually itchy rash. It is commonly called hives. The raised areas are known as wheals or welts. They can appear anywhere on the body, change shape, and move from one area to another.

Urticaria happens when immune cells in the skin release histamine and other chemicals. These chemicals allow fluid to leak from small blood vessels, causing temporary swelling and redness. On brown or black skin, redness may be less noticeable, but the raised texture and itching are still present.

A single wheal usually fades within 24 hours without leaving a scar. New wheals may continue to appear as older ones disappear.

Urticaria lasting less than six weeks is called acute urticaria. If symptoms occur on most days for six weeks or longer, it is called chronic urticaria. Chronic does not necessarily mean permanent.

Some people also develop angioedema. This is deeper swelling, often affecting the lips, eyelids, hands, feet, or genitals. Angioedema may feel tight, sore, or warm rather than itchy.

Most urticaria is uncomfortable rather than dangerous. However, hives accompanied by throat swelling, breathing difficulty, faintness, or other signs of a severe allergic reaction need emergency care.

Wheals may be small and round, or they may join together into larger patches. Their borders are usually clear, and their centres may look paler than the surrounding skin.

Typical features include:

• Raised, smooth welts of different shapes and sizes
• Itching, sometimes with burning or stinging
• Wheals that fade in one place and appear elsewhere
• Deeper swelling around the lips, eyelids, hands, or feet

The rash may come and go over minutes or hours. Heat, pressure, exercise, or scratching can make it more noticeable.

An individual mark that stays in the same place for longer than 24 hours, is painful rather than itchy, or leaves bruising or dark staining is less typical. These features can occur with other conditions, including inflammation of small blood vessels called urticarial vasculitis.

Urticaria is caused by activation of mast cells, which are immune cells found in the skin. They release histamine and other substances that cause itching and swelling.

Acute urticaria can follow a viral or bacterial infection. It can also be triggered by a medicine, insect sting, food allergy, or contact with substances such as latex. In many cases, no single cause is found.

Medicines that can trigger or worsen hives include some antibiotics and non-steroidal anti-inflammatory drugs like ibuprofen or naproxen, or NSAIDs, such as ibuprofen and aspirin. Do not stop a prescribed medicine without discussing it with a healthcare professional unless you are having a suspected severe allergic reaction and need emergency help.

Chronic urticaria is often not caused by an external allergy. In chronic spontaneous urticaria, wheals or swelling develop without one consistent outside trigger. In some people, the immune system appears to activate mast cells by mistake. Thyroid autoimmunity and some other autoimmune conditions may occur alongside it, but many people have no related illness.

Chronic inducible urticaria is brought on by a physical stimulus. Examples include:

• Scratching or rubbing the skin, called dermographism
• Cold air, water, or objects
• Heat, sweating, or exercise
• Firm or prolonged pressure
• Sunlight or vibration
• Contact with water, which is uncommon

Stress does not mean the symptoms are imaginary. Emotional stress can worsen itching or trigger flares in some people, but it is not always the underlying cause.

Urticaria is not contagious.

Urticaria is usually diagnosed from the appearance and timing of the rash. A healthcare professional may ask how long each wheal lasts, whether it leaves a mark, and whether swelling or breathing symptoms occur. Photographs can help if the rash has disappeared before an appointment.

You may be asked about recent infections, new medicines, foods, insect stings, work exposures, and physical triggers. Keeping a brief record of symptoms and possible triggers can reveal patterns.

Most people with ordinary acute urticaria do not need extensive testing. Allergy testing may be useful when symptoms repeatedly follow a specific food, medicine, sting, or exposure within a consistent time frame. Broad allergy panels are unlikely to find the cause of chronic spontaneous urticaria and can produce misleading results.

If physical urticaria is suspected, a supervised provocation test may be used. This involves carefully exposing a small area to the suspected trigger, such as cold or pressure.

Blood tests may be considered when symptoms are chronic or when the history suggests another condition. A skin biopsy, which removes a small sample for examination, is uncommon but may be needed for painful, long-lasting, or bruise-like lesions.

Treatment aims to control itching, reduce wheals and swelling, and limit known triggers.

Second-generation H1 antihistamines like cetirizine or loratadine are usually the main treatment. These medicines block the effects of histamine and are less likely to cause drowsiness than older antihistamines. For chronic urticaria, they may work better when taken regularly rather than only during a flare.

If a standard amount does not control chronic symptoms, a clinician may recommend a different antihistamine or a supervised increase. Do not increase the amount on your own. Even medicines described as non-drowsy can affect alertness in some people.

Simple measures may also help:

• Use cool compresses and avoid very hot showers
• Wear loose clothing if rubbing or pressure triggers symptoms
• Use fragrance-free skin products if the skin feels sensitive
• Avoid a confirmed trigger where this is practical and safe
• Discuss medicines that seem to worsen symptoms before changing them

Restrictive diets are not routinely helpful unless there is evidence of a specific food allergy. Removing many foods without guidance can make nutrition more difficult and may not improve chronic urticaria.

For chronic spontaneous urticaria that remains troublesome despite antihistamines, a specialist may offer omalizumab. This is an injected medicine that reduces allergic immune signalling. Other specialist treatments, such as ciclosporin, may be considered in selected cases and require monitoring.

A short course of an oral corticosteroid is sometimes used for a severe flare. These medicines are not suitable for ongoing control because repeated or long-term use can cause important side effects.

Adrenaline, also called epinephrine, treats anaphylaxis. It is not a routine treatment for uncomplicated chronic hives. People with a known risk of anaphylaxis may be given an adrenaline auto-injector and an emergency plan.

Persistent itching can disturb sleep, concentration, work, school, and exercise. Unpredictable swelling may also cause anxiety or affect confidence. These effects are valid reasons to seek better symptom control.

Angioedema can make eating, speaking, walking, or using the hands uncomfortable, depending on where swelling occurs. Swelling around the eyes may temporarily affect vision because the eyelids are difficult to open.

Urticaria itself usually does not scar. Scratching may break the skin, and temporary colour changes can follow irritation.

Anaphylaxis is a separate, severe allergic reaction that can include hives. It may affect breathing, circulation, or several body systems at once. Chronic spontaneous urticaria usually does not progress into anaphylaxis, but new hives after a likely allergen should be assessed alongside any other symptoms.

Urticaria cannot always be prevented. This is especially true for chronic spontaneous urticaria, where there may be no avoidable outside cause.

When a specific trigger has been confirmed, reducing exposure may prevent some episodes. This could include avoiding a particular medicine, protecting the skin from cold, or reducing prolonged pressure. Complete avoidance is not always possible, so treatment may still be needed.

Avoid labelling a food as the cause based only on a single uncertain episode. A clear history and, when appropriate, allergy assessment can help prevent unnecessary dietary restrictions.

If you have had anaphylaxis, follow your emergency plan and carry prescribed adrenaline devices as instructed.

Acute urticaria often settles over days or weeks. The rash may disappear and return several times during that period. If an infection triggered it, the hives may continue briefly after other symptoms improve.

Chronic urticaria tends to fluctuate. You may have quiet periods followed by flares, and the pattern can change over months or years. Many cases eventually settle, but it is not possible to predict exactly when this will happen for one person.

Chronic inducible urticaria may continue while the physical trigger remains active. The amount of exposure needed to cause symptoms can change over time.

A symptom record can be useful without becoming overly detailed. Note when the rash appeared, how long individual marks lasted, any swelling, medicines taken, and obvious exposures. Photographs showing the rash clearly can support follow-up.

Regular follow-up is appropriate if symptoms last six weeks or longer, keep returning, interfere with sleep or daily activities, or are not controlled by initial treatment. Follow-up can also check whether the diagnosis still fits and whether treatment needs adjusting.

Call emergency services if hives or swelling occur with:

• Trouble breathing, wheezing, or a tight throat
• Swelling of the tongue or inside the mouth
• Difficulty swallowing or a sudden change in voice
• Fainting, severe dizziness, confusion, or collapse
• Rapidly worsening symptoms after a food, medicine, or insect sting

Use prescribed adrenaline immediately if your emergency plan tells you to. Do not wait to see whether symptoms settle.

Seek urgent medical advice for rapidly increasing facial swelling, significant lip swelling, or a first episode of angioedema, even if breathing is currently normal. Swelling linked to certain blood pressure medicines may need prompt assessment.

Arrange routine medical care if the rash lasts for six weeks, repeatedly returns, disrupts daily life, or does not improve with recommended antihistamines. Also seek assessment if individual lesions remain longer than 24 hours, are painful, leave bruising, or occur with fever, joint pain, or feeling generally unwell.

Is urticaria the same as hives?

Yes. Hives is the everyday name for urticaria. The raised marks are called wheals or welts.

How long does urticaria last?

Each wheal usually disappears within 24 hours, but new ones may keep forming. Acute urticaria lasts less than six weeks. Chronic urticaria continues or repeatedly returns for six weeks or longer.

Does chronic urticaria mean I have a food allergy?

Usually not. Food allergy is more likely when the same food repeatedly causes symptoms soon after eating, especially with mouth swelling, vomiting, breathing symptoms, or faintness. Chronic spontaneous urticaria commonly has no specific food trigger.

Why do my hives seem worse at night?

Body temperature, pressure from bedding, natural changes in hormone and histamine activity, and greater awareness of itching may contribute. Night-time symptoms do not identify a particular cause.

Can stress cause urticaria?

Stress can trigger or worsen symptoms in some people, particularly when urticaria is already active. It is not the only possible cause, and the physical symptoms are real.

Why do the marks move around?

Each wheal is caused by temporary leakage of fluid into one area of skin. As that swelling fades, mast cells may become active somewhere else, making the rash appear to move.