What is it?

Urticaria is an itchy, lumpy, red rash, often called hives, wheals or nettle rash. Angioedema is swelling, often of the face or lips.

Over half of patients with urticaria will also have angioedema. Less frequently angioedema occurs without urticaria.

Chronic urticaria is not associated with severe allergic reactions (anaphylaxis) and adrenaline autoinjector devices are not required.

It can however be associated with difficulty sleeping and problems concentrating at school (impact on quality of life). Effective management is therefore important.

What is the difference between acute and chronic urticaria?

Acute urticaria is a rash that lasts for any period up to 6 weeks. It may be due to an allergy. Viral infections are another common cause.

Chronic urticaria lasts more than 6 weeks. Individual spots can last less than 24 hours and occur most days. It affects 1 in 200 children.

Acute intermittent urticaria is the name used to describe a rash that lasts for more than 6 weeks and just occurs now and again.

Why does it happen?

The cause of chronic urticaria is not fully understood but it is known not to be an allergy. Some children can have chronic urticaria due cold, heat, sunlight, exercise, scratching, rubbing (see photo of dermographism) and even stress. Often no cause can be found, in which case it is called idiopathic urticaria.

Some medicines can make swelling worse e.g. ibuprofen, ACE inhibitors. Patients on ACE inhibitors should see their doctor, who may consider changing to an alternative medicine.

Dermographism is when your skin is very sensitive and will show a red raised rash on mere rubbing.

How is chronic urticaria diagnosed?

The diagnosis is made on the history and pattern of the rash. Usually no tests are needed.

In a minority where individual spots last more than 24 hours or there is associated bruising your doctor may consider other medical causes, for example hereditary angioedema when there may also be a family history. In this case special tests are required.

How is it treated?

When the rash is made worse by specific triggers, these should be avoided. If hot showers bring out the rash, the water temperature should be reduced a little.

A regular dose of a non-drowsy antihistamine is the treatment of choice. The medicine may need to be taken for many months or even years.

If this does not work then your doctor may increase the dose or add other medicines. Use of steroids for more than a few days is not recommended because of side effects.

If your child only gets angioedema and not urticaria, it is important to make sure that certain medicines are avoided, for example ACE inhibitors such as enalapril that may be the cause of the problem.

How long will the problem last?

The problem may settle after a number of months, but in 3 of 4 children the rash may go on for 3 years or more.

Where can I find more information on chronic urticaria and angioedema?