Introduction

Urticaria also known as hives, weals, welts or nettle rash is a raised, itchy rash that appears on the skin.It may appear on one part of the body or be spread across large areas.

The rash isusually very itchy and ranges in size from a few millimetres to the size of a hand.

Although the affected area may change inappearance within 24 hours, the rash usually settles within a few days.

Doctors may refer to urticaria as either:

• acute urticaria if the rash clears completely within six weeks
• chronic urticaria in rarer cases, where the rash persists or comes and goes for more than six weeks, often over many years

A much rarer type of urticaria, known as urticaria vasculitis, can cause blood vessels inside the skin to become inflamed.In these cases, the weals last longer than 24 hours, are more painful, and can leave a bruise.

When to seek medical advice

Visit your GP if your symptoms don't go away within 48 hours.

You should also contact your GP if your symptoms are:

• severe
• causing distress
• disrupting daily activities
• occurring alongside other symptoms

Who's affected by urticaria?

Acute urticaria (also known as short-term urticaria) is a common condition, estimated to affect around one in five peopleat some point in their lives.

Children are oftenaffected by the condition, as well as women aged 30 to 60, and people with a history of Indoor allergy .

Chronicurticaria (also known as long-term urticaria) is much less common, affectingup tofivein every 1,000 people in England.

What causes urticaria?

Urticaria occurs when a trigger causes high levels of histamine and other chemical messengers to be released in the skin.

These substances cause the blood vessels in the affected area of skin to open up (often resulting inredness or pinkness) and become leaky. This extra fluid in the tissues causes swelling and itchiness.

Histamine is released for many reasons, including:

• anallergic reaction such as a food allergy or a reaction to an insect bite or sting
• cold or heatexposure
• infection such as a cold
• certain medications such as non-steroidal anti-inflammatory drugs (NSAIDs) or antibiotics

However, in many cases of urticaria, no obvious cause can be found.

Some cases of long-term urticaria may becaused by the immune system mistakenly attacking healthy tissue. However, this is difficult to diagnose and the treatment options are the same.

Certain triggers may also make the symptoms worse. These include:

• drinking alcohol or caffeine
• emotional stress
• warm temperature

They may also ask you questions to find out what triggered your symptoms.

If your GP thinks that it's caused by an allergic reaction, you may be referred to an allergy clinic foran allergy test . However, if you've had urticaria most days for more than six weeks, it's unlikely to be the result ofan allergy.

You may also be referred for a number of tests, including a full blood count (FBC) ,to find out whetherthere's an underlying cause of your symptoms.

Antihistamines are available over the counter at pharmacies speak to your pharmacist for advice.

A short course of steroid tablets (oral corticosteroids ) may occasionally be needed for more severe cases of urticaria.

If you have persistent urticaria, youmay be referred to a skin specialist (dermatologist). Treatment usually involves medication to relieve the symptoms, while identifying and avoiding potential triggers.

Read about treating urticaria .

Complications of urticaria

Around a quarter of people with acute urticaria and half of people with chronic urticaria also develop angioedema, which is a deeper swelling of tissues.

Chronic urticaria can also be upsetting and negatively impact a person's mood and quality of life.

Angioedema

Angioedema is swelling in the deeper layers of a person's skin. It's often severe and is caused by a build-up of fluid.The symptoms of angioedema can affect any part of the body, but usually affect the:

• eyes
• lips
• genitals
• hands
• feet

Medication such as antihistamines and short courses of oral corticosteroids (tablets) can be used to relieve the swelling.

Chronic urticaria can have a considerable negative impact on a person's mood and quality oflife. Living with itchy skin can be particularly upsetting.

One study found that chronic urticaria can have the same negative impact as heart disease . It also found that one in seven people with chronic urticaria had some sort of psychological or emotional problem, such as:

• stress
• anxiety
• depression

See your GP if your urticaria is getting you down. Effective treatments are available to improve your symptoms.

Talking to friends and family can also improve feelings of isolation and help you cope better with your condition.

Read about how talking to others can help .