What is chronic urticaria?
Urticaria (sometimes called hives) is an itchy rash caused by tiny amounts of fluid that leak from blood vessels just under the skin surface. Urticaria is classed as:
- Acute urticaria - if it develops suddenly and lasts less than six weeks. Most cases last 24-48 hours. About 1 in 6 people will have at least one bout of urticaria in their life. It can affect anyone at any age. Some people have recurring bouts of acute urticaria.
- Chronic urticaria - if it persists long-term. Chronic means persistent or ongoing. In chronic urticaria a rash develops on most days for at least six weeks. This is uncommon. About 1 in 1,000 people develops chronic urticaria at some stage in their life. It is twice as common in women as in men. Some people have an urticarial rash on and off for months, or even years.
The rest of this leaflet deals only with chronic urticaria.
What does the rash of urticaria look like?
The rash can affect any area of skin. Small raised areas called weals develop on the skin. The weals look like mild blisters and are itchy. Each weal is white or red and is usually surrounded by a small red area of skin which is called a flare. The weals are commonly 1-2 cm across but can vary in size. There may be just a few but sometimes many develop over various parts of the body. Sometimes weals that are next to each other join together to form larger ones. The weals can be any shape but are often circular.
As a weal fades, the surrounding flare remains for a while. This makes the affected area of skin look blotchy and red. The blotches then fade gradually and the skin returns to normal. Each weal usually lasts less than 24 hours. However, as some fade away, others may appear. It can then seem as if the rash is moving around the body. The rash may clear completely only to return a few hours or days later.
Are there any other symptoms?
- The appearance of the rash and the itch can cause distress.
- A related condition called angio-oedema occurs from time to time in about half of people with chronic urticaria. In this condition some fluid also leaks into deeper tissues under the skin, which causes the tissues to swell.
- The swelling of angio-oedema can occur anywhere in the body but most commonly affects the eyelids, lips and genitals.
- Sometimes the tongue and throat are affected and become swollen. The swelling sometimes becomes bad enough to cause difficulty breathing.
- Symptoms of angio-oedema tend to last longer than urticarial weals. It may take up to three days for the swollen areas to subside and go.
- A variation called vasculitic urticaria occurs in a small number of cases. In this condition the weals last for more than 24 hours, they are often painful, may become dark red, and may leave a red pigmented mark on the skin when the weal goes.
What causes chronic urticaria?
A trigger is thought to cause the release of chemicals (such as histamine) from cells in the skin. The chemicals cause fluid to leak from tiny blood vessels under the skin surface. The fluid pools to form weals. The chemicals also cause the blood vessels to open wide (dilate) which causes the flare around the weals. The trigger is not known or identified in many cases. Possible causes in some cases include the following:
- In up to a third of cases the cause may be an autoimmune problem. Autoimmune means that the body's antibodies cause disease. Antibodies normally fight off germs (viruses and bacteria). In some people, one type of antibody attaches to cells under the skin and causes them to release histamine and other chemicals. The reason why this happens is not clear.
- An allergy to a food, medicine or parasite (such as worms in the gut) is an uncommon cause of chronic urticaria. A skin specialist may advise tests if an allergy is suspected.
- Physical urticaria. This is when a localised rash appears when the the skin is physically stimulated. The most common is called dermographism when a rash develops over areas of skin which are firmly stroked. Sometimes an urticarial rash is caused by heat, cold, emotion, exercise, or strong sunlight. See separate leaflet called 'Physical Urticarias'. This kind of urticaria often causes bouts of acute symptoms, but sometimes causes persistent chronic symptoms.
- A bacterium (germ) called Helicobacter pylori which is commonly found in the stomach may be a factor in some cases. If you are infected with this bacterium and it is cleared with treatment, it may cure the problem with urticaria.
Is chronic urticaria serious?
The rash is usually itchy. Each weal usually lasts less than 24 hours. However, as the rash may constantly come and go, the ongoing itch may cause distress and difficulty sleeping. Bouts of angio-oedema which occur from time to time in about half of people with chronic urticaria can sometimes cause serious breathing difficulties.
What is the course and outcome (prognosis) of chronic urticaria?
Chronic urticaria tends to come and go. You may have times when the rash appears on most days, and then times when the rash may go away for a while. The severity of the rash and itch varies from person to person. Some things such as heat, cold, menstrual periods, stress, or emotion may make the rash flare up worse than usual.
- Symptoms may go away completely after a few months, but the condition lasts several years in some cases.
- In about half of cases, symptoms go within 3-5 years after it first starts.
- In about 1 in 5 cases the symptoms persist on and off for more than 10 years.
What are the treatments for chronic urticaria?
The release of histamine under the skin is involved in causing urticaria. Antihistamines block the action of the histamine. Most affected people have at least partial relief, and sometimes total relief, of their symptoms with antihistamines. There are various antihistamines:
- Some older ones tend to cause drowsiness, but may be useful to take at bedtime.
- Modern antihistamines are less likely to cause drowsiness. If needed, you can take them regularly.
- Some people take an older sedating antihistamine at bedtime, and a modern non-sedating one during the daytime.
- Some people respond to one antihistamine better than another. If one antihistamine has not helped much, a different one may suit better. It is usually worth trying an antihistamine for 1-2 weeks before deciding if it is helping or not.
- Some people take antihistamines 'as required' when symptoms flare up. However, if the rash usually develops on three or more days each week, it is best to take the antihistamine every day whether the rash is present or not. This is to prevent the rash and itch from developing rather than taking medication now and then in response to a rash that develops.
Soothing the rash
Creams such as menthol in aqueous cream are useful to cool the skin and help to relieve itch. A tepid bath or shower may relieve the itch before bedtime and help you to sleep.
Avoiding triggers or aggravating factors
Occasionally a trigger such as a food is identified which causes the rash. You may then be able to avoid it. However, it is unusual to identify a trigger. For example, if a food trigger is suspected, then you may be asked to keep a food diary to try to identify which food is responsible.
Various other factors may make symptoms worse (but are not the main trigger). The following are things that some people have found helpful, but there is little proof that they work in everybody:
- Try avoiding tight clothes as weals sometimes tend to occur at sites of local pressure. For example, under belts, under tight-fitting shoes, etc.
- Try keeping cool as urticaria may tend to flare up in warmer conditions. In particular, keep the bedroom cool at night.
- Some things worth considering include: alcohol, hot baths, strong sunlight, and undue emotion. If you think any of these are making symptoms worse then it may be helpful to avoid them.
- See a doctor if you think a medicine is making symptoms worse, as a change in medication may be an option. Some medicines worth considering include: aspirin, anti-inflammatory painkillers, codeine, and angiotensin-converting enzyme (ACE) inhibitors.
Steroids reduce inflammation and may ease urticaria. However, it is not a usual treatment due to the serious side-effects which are likely to occur if you take steroids regularly. However, a short course of steroids may be advised occasionally for a bad flare-up of symptoms.
Various other treatments have been tried with variable success. One may be advised by a specialist. For example:
- Strict diets which avoid possible food triggers.
- Immunosuppressant therapy (but there is a risk of serious side-effects).
- Other medicines which have limited evidence of working in most cases, but may work in a few cases.
- If relevant, clearing H pylori infection of the gut. (See separate leaflet called 'Helicobacter Pylori and Stomach Pain'.)
Treatment of associated angio-oedema
Antihistamines usually help to reduce the swelling of angio-oedema. Occasionally, an adrenaline injection and emergency hospital treatment is necessary if the swelling affects the throat and breathing becomes difficult.
For a list of websites that contain pictures of skin conditions including urticaria see www.patient.co.uk/showdoc/1097/
Further reading & references
- Evaluation and management of urticaria in adults and children, British Association of Dermatologists (2007)
- Urticaria, Clinical Knowledge Summaries (2007)
- Zuberbier T, Maurer M; Urticaria: current opinions about etiology, diagnosis and therapy. Acta Derm Venereol. 2007;87(3):196-205.
- Daniel J Hogan; Urticaria, Chronic, eMedicine, May 2010
|Original Author: Dr Tim Kenny||Current Version: Dr Laurence Knott|
|Last Checked: 25/11/2010||Document ID: 4449 Version: 39||© EMIS|
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.