Urticaria or Hives

What is urticaria?

Urticaria, also known as hives or nettle rash, is a common condition that causes itchy, raised swellings in the skin called wheals. Skin cells known as mast cells release histamine and other chemicals, causing small blood vessels to leak fluid into the surrounding skin.

Some people also develop angioedema, which is deeper swelling of the skin and the tissues beneath it. Angioedema most often affects the lips, eyelids, face, hands, feet and genitals.

Who gets it?

Urticaria is very common, and up to 1 in 5 people will have it at some point in their life. It can occur at any age, although it is rare in young babies.

What causes it?

Urticaria that settles within six weeks is called acute. It is often triggered by a viral infection, and sometimes by a medicine, such as an antibiotic or anti-inflammatory painkiller, or by a food allergy. In children, food allergies, for example to milk, nuts, fruit or shellfish, are more common triggers, and bee and wasp stings can also cause it. Often no cause is found.

Chronic urticaria lasts longer than six weeks. In most people it is not caused by an allergy to food or anything in the environment, and allergy tests are usually not helpful. Chronic spontaneous urticaria, the most common form, occurs without any external trigger and in many people is caused by the immune system producing antibodies that activate mast cells. It is sometimes associated with autoimmune thyroid disease.

Inducible urticaria is brought on by a specific physical trigger. Examples include scratching or rubbing the skin (dermographism), pressure from tight clothing or carrying bags, cold, heat, sunlight, water, exercise and a rise in body temperature (cholinergic urticaria). Some people have both spontaneous and inducible urticaria.

Factors such as stress, alcohol, infections, heat, tiredness and anti-inflammatory painkillers including aspirin and ibuprofen can make existing urticaria worse.

Is it hereditary or contagious?

The vast majority of urticaria is not inherited, and it is not contagious. A rare, inherited condition called hereditary angioedema causes recurrent swelling without wheals and is managed differently.

What does it look and feel like?

Wheals are raised, itchy swellings that can be small spots or large patches that join together. They are pink or red on lighter skin and may look skin-coloured or slightly darker on brown and black skin. They can appear anywhere and move around the body. A single wheal normally disappears within a day and leaves no trace, though fresh ones can continue to come up.

Angioedema swellings feel tight, uncomfortable or painful rather than itchy, and can take up to three days to settle.

Chronic urticaria can have a major effect on sleep, work and quality of life.

When to seek urgent help

Get emergency help straight away for a swollen tongue or throat, trouble breathing or swallowing, a hoarse voice, wheezing, or feeling faint or dizzy, because these can signal anaphylaxis.

How is it diagnosed?

Urticaria is diagnosed from the history and the appearance of the wheals, and photographs of the rash can be very helpful. No test can reliably pinpoint the cause. For chronic urticaria, a few simple blood tests may be recommended. Extensive allergy testing is not usually needed unless the history suggests a specific allergic trigger. If wheals last longer than 24 hours, leave bruising, or are painful rather than itchy, a skin biopsy may be considered to look for a condition called urticarial vasculitis.

What are the treatment options?

Dr Mounsey will review your history to look for triggers and decide whether any tests are useful, as most cases of chronic urticaria have no external cause. The mainstay of treatment is a non-sedating antihistamine taken every day, often at up to four times the standard dose under medical supervision. If symptoms continue, options include a biologic injection called omalizumab or ciclosporin tablets. Short courses of oral steroids are reserved for severe flares. Dr Mounsey will also advise on medicines that can make urticaria worse, such as some painkillers, and on managing any associated swelling.

What is the outlook?

Acute urticaria usually settles within days to weeks. In about half of people with chronic spontaneous urticaria, it lasts 6 to 12 months and then gradually settles, although it can last longer and the course is unpredictable. Around 7 in 10 people are clear within three years, and most within five years. It can usually be well controlled in the meantime.

More information

British Association of Dermatologists patient leaflet: https://www.bad.org.uk/pils/urticaria-and-angioedema

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.