WHAT ARE URTICARIA & ANGIOEDEMA?
Urticaria is common, and affects about 20% of people at some stage of their lives.  It is also known as hives, nettle rash, or welts.  The short-lived swellings of urticaria are known as wheals. Angioedema is a deeper form of urticaria.

An affected individual may have urticaria alone, or angioedema alone, or both together.  The most common form is called ‘ordinary urticaria’, which is usually divided into ‘acute’ and ‘chronic’ forms.  In ‘acute’ urticaria/angioedema, the bout lasts from a few days up to six weeks. Chronic urticaria, by definition, lasts for more than six weeks. Other less common types – such as the physical urticarias - are described later in this leaflet. They include urticarial vasculitis (in which urticaria is due to an inflammation of the blood vessels) and contact urticaria (in which substances, such as fruit, nuts or rubber, cause urticaria when they are applied to the skin).

WHAT CAUSES URTICARIA & ANGIOEDEMA?
Both are caused by the release of histamine from mast cells (allergy cells) within the skin.  This can be triggered in many ways, for example by exercise, by pressure on the skin, and by other physical factors as well as by foods, drugs and infections. However in the common ‘ordinary’ form of urticaria and angioedema, it is unusual for an external cause to be identified. In some patients with ordinary chronic urticaria, the release of histamine from skin mast cells is triggered by factors circulating in the blood, such as antibodies directed against their own mast cells - a process known as autoimmunity. Tests for this are not routinely available, and generally do not alter the treatments used.
Often no cause for acute urticaria can be found, but sometimes it may be caused by infections such as a cold, ‘flu or a sore throat. Almost any medicine can cause ‘acute’ urticaria but painkillers (especially aspirin and medicines like ibuprofen), antibiotics (especially penicillins), and vaccinations, are most likely to be responsible. Angioedema is particularly caused by a type of drug used to treat high blood pressure (ACE inhibitors). Rarely foods are responsible, including nuts, fish, tomatoes, vegetables and berries. 

WHAT ARE THE SYMPTOMS OF URTICARIA & ANGIOEDEMA?
The main symptom of urticaria is itching: angioedema, however, may not be itchy.  Although urticaria can be distressing, because of itching and its appearance, it has no direct effect on general health.

ARE URTICARIA & ANGIOEDEMA HEREDITARY?
The ‘ordinary’ common type of urticaria and angioedema is not hereditary.

WHAT DO ORDINARY URTICARIA & ANGIOEDEMA LOOK LIKE?
The wheals of urticaria may be pale, pink or red, and may look like nettle stings.  They can be different shapes and sizes; often they are surrounded by a red flare.  They are usually itchy.  As the raised wheals flatten, they leave red marks that usually disappear in a day.  New wheals may then appear in other areas.  In ordinary urticaria the wheals can occur anywhere on the body, at any time, and usually fade within a day. The pale or pink, deeper swellings of angioedema occur most frequently in the eyelids, lips and sometimes in the mouth. They may not be itchy, and usually settle in a few days. If the hands are affected, they may feel tight and painful.