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Urticaria

Published by Bupa's health information team, September 2008.

This factsheet is for people who have urticaria, or who would like information about it.

Urticaria is a skin condition in which red, itchy swellings called weals or hives appear on your skin. In most cases, the weals go away within a couple of hours and are not serious.

• About urticaria
• Symptoms of urticaria
• Causes of urticaria
• Complications of urticaria
• Diagnosis of urticaria
• Treatment of urticaria
• Questions and answers
• Sources

About urticaria

In urticaria, a chemical called histamine is released from the cells in your skin. This causes fluid from blood vessels underneath the surface of your skin to leak out. This results in the raised patches (weals) that you see on the surface of your skin. The histamine also causes the weals to itch.

If urticaria affects the deeper layers of skin, it can cause even larger swellings, called angioedema. Urticaria and angioedema can occur together or separately.

Types of urticaria

In most people who get urticaria, the weals appear suddenly, anywhere on the body. This can often be for no apparent reason. This is known as ordinary urticaria. The individual weals usually go away within 24 hours, but new ones may appear.

This type of urticaria can be acute or chronic. The terms acute and chronic refer to how long a person has a condition, not how serious it is.

• In acute urticaria, the swellings are a one-off episode, which usually lasts for a few days or weeks. This type of urticaria is very common, affecting one out of six people at some point in their lives.
• In chronic urticaria, the problem persists for longer than six weeks. This is a rarer form of urticaria that may continue for months or years, with symptoms often coming and going. Chronic urticaria goes away within six months in about half the people who have it.

The following types of urticaria usually have a specific cause.

• Physical urticaria - this is when you repeatedly develop urticaria in response to the same physical trigger factor, such as pressure to the skin, an increase in your body temperature (eg after exercise or eating spicy food), cold temperature, sunlight or water.
• Contact urticaria - this follows contact with a particular substance, such as certain chemicals, cosmetics, foods, plants, rubber or animals.
• Vasculitic urticaria - this is a rare type of urticaria caused by inflammation of your blood vessels.

You may have more than one type of urticaria at the same time.

Symptoms of urticaria

Urticaria doesn't usually make you feel unwell. The only symptoms you will have are in relation to the weals on your skin. The weals:

• may be red, pink or white and are often surrounded by red skin
• are usually itchy
• eventually flatten, leaving red marks that usually go away within 24 hours
• may come back in the same place or on a different patch of skin, hours or days after they have gone away

Angioedema often affects the eyelids, lips and sometimes the mouth. These swellings may be painful, rather than itchy.

You should visit your GP for advice if you get these symptoms.

Causes of urticaria

Urticaria happens when histamine is released by the cells in your skin. Sometimes a trigger factor for this can be found. For example:

• acute episodes can follow a cold, flu or sore throat; allergic reactions to certain medicines, an insect sting or certain types of food can also cause the release of histamine, leading to urticaria
• chronic urticaria can sometimes be due to an autoimmune reaction - this is when antibodies from your immune system attack your own body, causing your skin cells to release histamine

If you have chronic urticaria, certain factors may make your urticaria worse, such as some types of medicine, stress and alcohol.

However, often, the cause for urticaria can't be found. Even when there are known trigger factors (such as with the physical urticarias), it is not always clear why some people develop this type of reaction.

Some people may develop angioedema without any urticaria. This is much more likely to be due to a reaction to certain medicines, such as angiotensin converting enzyme (ACE) inhibitors. Rarely, it can be due to a genetic problem. If you get angioedema but have never had urticaria, you should see your GP.

Complications of urticaria

If angioedema affects your airway, it may make it hard for you to breathe. You should seek urgent medical attention if you have trouble breathing.

Very rarely, urticaria can develop into a more serious type of reaction called anaphylaxis. This is most common in urticaria caused by an allergic reaction or a physical urticaria. Anaphylaxis is a severe allergic reaction affecting your whole body rather than just your skin. It can be life-threatening if you don't get medical help straight away.

If you develop this condition, you may have the following symptoms in addition to urticaria:

• feel faint or even collapse
• have trouble breathing
• feel sick or be sick
• have palpitations (when you can feel your heart beating faster)

You should seek urgent medical attention if you get these symptoms.

Diagnosis of urticaria

Your GP will usually be able to diagnose urticaria just from examining your skin, or from what you tell him or her if your swellings have already gone down. He or she will try to find out what caused the reaction by asking you questions about when and where your urticaria came on - but this isn't always possible.

If your urticaria seems to have been a one-off episode, you probably won't need any treatment or further tests at all.

If your GP suspects an allergy may have caused your urticaria, he or she may suggest you have a skin prick test to test for the suspected allergen, or ask you to have a blood test. If you are thought to have a physical urticaria, your GP may carry out various tests to check whether the suspected cause (eg cold or pressure to the skin) sets off a reaction.

Your GP may also check your blood pressure and pulse, listen to your chest and examine your ears, nose and throat. This is to check for signs of angioedema affecting your airway or anaphylaxis. You will need to be admitted to hospital if you are found to have symptoms of these complications.

Your GP may refer you to a dermatologist (a doctor specialising in conditions affecting the skin) or an immunologist (a doctor specialising in conditions affecting the immune system) for further tests if your urticaria isn't responding to normal treatments, or if it keeps coming back.

Treatment of urticaria

Treatment of ongoing urticaria is aimed at relieving your symptoms and keeping your condition under control. Although there is no cure as such, there is a good chance for all types of urticaria that you will eventually make a full recovery from your condition.

Antihistamines

Your GP may advise you to take an antihistamine to control your symptoms. These medicines reduce the itching in most people. Your GP may prescribe antihistamines, and you can also buy them from a pharmacy, supermarket, corner shop or garage. If your symptoms don't respond to the treatment, your GP may advise trying a different type of antihistamine after a couple of weeks, or may increase the dose of your medicine.

Some antihistamines are sedating (make you feel sleepy). Your GP may prescribe one of these specifically for you to take at night if the itch is interfering with your sleep.

Steroids

If you have a flare-up of severe symptoms, your GP may prescribe a short course of steroid tablets in addition to antihistamines. The steroids may help to make severe urticaria symptoms go away quicker.

Immunosuppressants

Very occasionally, you may be given newer treatments that work by suppressing the immune system (eg ciclosporin). These are only given to the most severely affected people, and usually by doctors in specialist skin and allergy centres.

Sources

• Urticaria. Clinical Knowledge Summaries. wwww.cks.library.nhs.uk, accessed 9 July 2008
• Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press, 2005: 642-643, 1034-1035
• Urticaria and angioedema. British Association of Dermatologists. www.bad.org.uk, accessed 9 July 2008
• Grattan CEH, Humphreys F. Guidelines for evaluation and management of urticaria in adults and children. Br J Dermatol 2007; 157:1116-1123

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Dr Mike Ardern-Jones, BSc, MBBS, MRCP, DPhil, Consultant Dermatologist, Southampton University NHS Trust and Spire Southampton Hospital, and by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: September 2008