Immunology - What is urticaria and angioedema?

Urticaria and angioedema are common conditions, with symptoms affecting approximately 1 in 5 people at some stage in their lives.

Patients may have both urticaria and angioedema during an attack or they may only suffer one of the two symptoms.

In most cases, symptoms are mild and short in duration. In other cases the symptoms can be more severe and last longer in duration.

Acute urticaria and/or angioedema lasts for any period of up to 6 weeks. This could be a response to an infection or due to an allergy.

Acute intermittent urticaria lasts for less than 6 weeks but can recur from time to time.

Chronic spontaneous urticaria (CSU) and/or angioedema - Chronic spontaneous urticaria (CSU) is defined by the presence of recurrent urticaria, angioedema, or both, for a period of six weeks or longer, without an identifiable external trigger. Around half of patients with CSU present with wheals/hives alone, associated angioedema occurs in approximately 40% of patients with CSU, and 10% present with angioedema only.
 
Urticaria is the medical term used to describe an itchy, raised, red rash on the skin. It may look like nettle rash or hives.

It can appear very quickly (sometimes within seconds). The rash usually lasts less than 24 hours at any one site, after which the skin returns to normal. It may ‘come and go’ affecting different parts of the body.

During an attack of urticaria the skin may feel:

• Itchy
• Prickly
• Tight
• Burning

The area covered by the rash can range from small with only a few spots or large involving wide areas of the body.

Angioedema is the medical term used to describe the swelling either occurring in the tissues beneath the skin or beneath the lining of the mouth, throat and gut.

The swellings can occur over minutes to hours and gradually subside over 24-48 hours, leaving normal skin. Swellings can sometimes cause itching.

Areas commonly affected include:

• Lips
• Face
• Tongue

Other areas affected may include:

• Hands, arms/legs
• Throat
• Mouth

Swellings in the mouth and throat can be frightening but are rarely life-threatening.

What is the cause of CSU and angioedema?

In some cases, this condition is thought to be caused by an autoimmune response. This means that there is a tendency in your immune system to cause some of the symptoms described above.

In rare cases, the condition can occur as a true allergic reaction. In these cases, the relationship between exposure to a substance causing allergic reaction and the development of a reaction is very clear e.g. peanut allergy.

The doctor or senior/advanced nurse specialist will diagnose this in clinic by taking a thorough medical history and obtaining blood or skin tests if required.

Chronic Spontaneous Urticaria (CSU) and angioedema

In most cases an allergic mechanism is rarely the cause of the rash and swellings.

Spontaneous CSU and angioedema is diagnosed when triggers have been excluded. Often the symptoms occur with no pattern, relationship or obvious outside trigger.

The attacks may tend to occur in clusters, with periods of good health in between.

Why do these attacks occur?

There is no completely satisfactory answer to why the attacks occur as yet. Some of the processes underlying the attacks are understood and described below:

Urticaria and angioedema are caused by the release of various substances, in particular a chemical in the body called histamine.  Histamine causes blood vessels to leak and allow the clear liquid part of the blood to pass into the tissues, causing them to become swollen.
 
Hives occur when histamine is released in superficial layers of the skin, and swelling occurs when histamine is released in the deeper tissues of the skin.

Histamine is normally present in the body and contained in tiny packages found in mast cells.

Mast cells are present in nearly all the tissues of the body, particularly in the skin and the lining of the mouth, throat and gut.

Histamine can be released as a result of allergy, heat, cold, pressure, trauma, stress and infections.

In chronic urticaria and angioedema, the histamine packages are unstable and release histamine easily with no clear trigger. There are some factors which may contribute to the histamine release described in the next section.

What triggers the attacks of swelling or the rash?

Substances which can make an attack of urticaria and angioedema more likely to occur are:

Aspirin and aspirin-like drugs (known as non-steroidal anti- inflammatory drugs or NSAIDS) - You should discuss taking these medications with your doctor. Many over-the- counter pain medications contain NSAIDs.

Stress - Symptoms are not caused by stress. However, being under pressure, anxious, tired, depressed or generally run down, can make the attacks more likely to occur or persist.

Infection - In some people, urticaria and angioedema may occur after an infection, such as cold or other viral infections.

Environmental conditions - Heat, cold and sunlight.

Alcohol

Narcotic medication e.g Codeine and Morphine

Menstruation of pre-menstrual period - Some women may observe hives/rash are worse during their menstrual cycle.

What can be done to treat the condition?

Sometimes the attacks come and go very quickly and don’t cause too much discomfort. Therefore, treatment is not necessary.

Treatment is required if the attacks are more frequent and troublesome.

The most commonly used treatment for CSU and angioedema is antihistamines.

Antihistamines block the effect of the histamine that is released and reduce the itching and rash in most people. If the urticaria occurs frequently then the antihistamines are best taken regularly as they are much better at preventing attacks than reversing them.

If attacks are rare, then taking antihistamines during the episode is recommended.

If attacks are happening frequently (especially if more than 2-3 times per week) then regular non-drowsy antihistamines are advised to manage the symptoms.

What if the treatment does not control the symptoms?

It is then possible to gradually reduce the dose of antihistamines until they can be taken as needed. High dose antihistamines are recommended for this condition by national and international guidelines.
 
In most people, taking high dose antihistamines will bring the swellings and rash under control. This may be required for a period of a few months.

Some antihistamines prescribed may cause drowsiness (even ones labelled non-drowsy). You will need to avoid driving and operating heavy machinery until you are sure the drowsiness has worn off.

If this treatment does not work, there are other options such as alternative antihistamines or an even higher dose.

There may be other drugs which the doctor might consider using. For severe attacks some patients are prescribed a short course of steroids.

This is only for emergency treatment of severe attacks, as there are too many side effects if taken for a long time.

What should I do if I develop swelling in the throat or the mouth?

Attacks of angioedema are uncomfortable and often frightening but usually not dangerous.

In a small number of patients, angioedema may develop in the tongue or throat or you may have difficulty swallowing or breathing during an attack. If this occurs, do not panic but call 999 for an ambulance and go to hospital for medical attention.

While you are waiting for help, you can take antihistamine tablets placing some ice in your mouth after chewing an antihistamine tablet. Angioedema usually develops over a period of hours and rarely causes breathing difficulties.

Will my symptoms get better?

For most patients, chronic spontaneous urticaria and angioedema symptoms get better over time. Patients can be any age when they first develop symptoms.

The average time you could be affected for is between a few weeks to months, although in some cases symptoms may persist for a year or more. It is impossible to predict for each patient how long their episodes will continue to occur.

Generally, the attacks become milder and at longer intervals and eventually disappear altogether. In some people the attacks stop suddenly and never return.

There is a small risk of having recurrence of the condition, sometimes many years after the first episode.

Contacts

Queries about your condition or treatment
(8am-4pm) (Mon-Fri, 8am to 4pm excluding bank and public holidays)

Immunology/Allergy Nurses
0161 206 5576 or salfordimmunology.nurses@nca.nhs.uk

Administrative and appointment queries
(Mon-Fri, 9am to 4pm excluding bank and public holidays) Immunology/Allergy Secretary on 0161 206 0522