Urticaria is also known as hives. It develops when a chemical called histamine is released from cells in your skin. Histamine causes fluid from blood vessels underneath the surface of your skin to leak out. This causes red bumps (weals) on the surface of your skin. Histamine also causes the weals to itch.
Urticaria affects about 20 in 100 people at some point in their lives.
It can be difficult to classify urticaria and often the various types can overlap. You may have more than one type of urticaria at the same time.
Urticaria can be the first sign of an allergic reaction, for example to a food or medicine, and usually develops within seconds or minutes of exposure to the trigger. It’s important that you seek urgent medical attention if you have an allergic reaction that gets worse or doesn’t improve after a few minutes, or you have symptoms including:
Ordinary urticaria is the most common form of this condition. With this type of urticaria, the weals usually appear suddenly, often for no apparent reason. The weals can appear anywhere on your body. The individual weals usually go away within 24 hours, but new ones may appear in different areas during or after this time.
Ordinary urticaria can be acute or chronic. The terms acute and chronic refer to how long you have a condition, not to how serious it is.
In acute urticaria, the swellings are a one-off episode, which usually lasts for a few days or weeks, but not more than six weeks. This type of urticaria is very common, affecting one in six people at some point in their lives. It’s more common in children and young adults.
In chronic urticaria, the problem persists for longer than six weeks, and can last for months or even years with symptoms often coming and going. Chronic urticaria affects about one in every 1,000 people and is more likely to develop in adults.
The following types of urticaria are usually associated with a particular trigger.
Urticaria doesn't usually make you feel unwell. The only symptoms are the weals on your skin that:
Urticaria happens when histamine is released by the cells in your skin. Often the cause of this can’t be found, but sometimes a specific trigger is identified.
If urticaria affects the deeper layers of your skin, it can cause larger swellings, called angio-oedema – this can also develop without urticaria.
Angio-oedema often affects your eyelids, lips and sometimes your mouth. These swellings may be painful rather than itchy and tend to last for longer than 24 hours, sometimes up to a few days. See your GP for advice if you get these symptoms with or without urticaria, as there are some medicines, for example angiotensin converting enzyme (ACE) inhibitors (mainly used to treat high blood pressure), that can cause this reaction. If your angio-oedema isn’t caused by medicines, your GP will refer you to a specialist.
If angio-oedema affects your airway, it may be hard for you to breathe, swallow or talk. You must get emergency help if you have these symptoms.
Very rarely, urticaria can develop into a more serious type of reaction called anaphylaxis. This is most common when urticaria is caused by an allergy. 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 anaphylaxis, you may have symptoms including:
If you think you or anyone else has symptoms of anaphylaxis, seek urgent medical attention.
Your GP will ask about your symptoms and examine you – this will usually be enough to diagnose urticaria. He or she will try to find out what caused the reaction by asking you questions about when and where your urticaria came on. There is one type of physical urticaria called dermographism, for which there is a specific test that can diagnose it. If you have this condition, severe red markings and swelling develop when your skin is stroked firmly. However, there are no particular tests for other forms of urticaria and often it isn’t possible to identify a cause.
If your GP thinks your urticaria may have been caused by an allergy, he or she may refer you to a specialist for further tests. This may involve a blood test or a skin-prick test to check for the suspected allergen (substance that causes an allergic reaction). If your doctor thinks you have physical urticaria, he or she may carry out various tests to see whether the suspected cause (for example, cold or pressure to your skin) sets off a reaction.
Your GP may refer you to a dermatologist (a doctor who specialises in skin conditions) or an immunologist (a doctor who specialises in conditions affecting your immune system) for further tests if the diagnosis is uncertain, if the usual treatments for urticaria aren’t effective or if it keeps coming back.
Treatment of non-allergic urticaria is aimed at relieving your symptoms and keeping your condition under control. Although there is no cure, there is a good chance that you will make a full recovery from urticaria, whatever type you have.
If your urticaria is mild and its cause can be identified, you may not need any treatment. Try not to come into contact with or eat whatever brought on the urticaria.
For both acute and chronic urticaria that is more serious, your GP is likely to advise you to take antihistamines to control your symptoms – these medicines reduce the itching in most people. You may need to take these regularly for several weeks or for as long as you have symptoms.
Your GP may prescribe antihistamines, or you can buy them over the counter at a pharmacy. If these aren’t effective in reducing your symptoms, your GP may advise you to try a different type or he or she may increase the dose of your medicine. You may need to take more than one type of antihistamine at the same time.
You may also be prescribed certain antihistamines, for example cimetidine, on an ‘off-label’ basis. This means that the medicines have been tested for their safety and effectiveness, but aren’t specifically licensed to treat urticaria. It’s up to your GP whether or not he or she will prescribe these for you.
Some antihistamines can make you feel drowsy. Your GP may prescribe one of these for you to take at night if the itchiness is stopping you from sleeping. It’s important that you don’t drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards.
If your urticaria is more severe, your GP may prescribe a short course of steroid tablets in addition to antihistamines. The steroids may help to make symptoms of severe urticaria go away more quickly.
Very occasionally, you may be given newer treatments (for example ciclosporin) that work by suppressing your immune system. These are only given to the most severely affected people, and usually by doctors in specialist skin and allergy centres.
You may be treated with adrenaline if you develop anaphylaxis. If you carry an adrenaline pen and have to use it, it’s important that you seek urgent medical attention afterwards, even if you feel fully recovered, as it’s possible the anaphylaxis will come back later.
Always ask your GP or pharmacist for advice and read the patient information leaflet that comes with your medicine.
Produced by Polly Kerr, Bupa Health Information Team, September 2012.