Urticaria, also known as hives affects around one in five people at least once during their lifetime. Urticaria appears as red or white circular swelling of skin, known as wheals. These circular swollen skin areas are often itchy or burning in nature.
Urticaria can appear anywhere on the skin. Individual wheals normally disappear on their own within 24 hours without leaving any marks on the skin. If the wheals are burning in nature, lasts longer than 24 hours and leaves bruise marks on the skin afterwards, urticarial vasculitis should be suspected. Urticarial vasculitis requires urgent medical attention for further investigations.
Angioedema consists of deeper swelling in the skin, which may take more than 24 hours to clear. It is not itchy and often involves the eyelids, lips and mouth. Sometimes, the swelling of angioedema may affect the tongue or throat, causing difficulty with breathing or swallowing. This can be alarming but is rarely life threatening. Some people develop urticaria and some develop angioedema and some suffer from both.
The most common form of urticaria is called spontaneous urticaria. In this type, no cause is usually identified and often patients have urticaria and angioedema occurring together. Spontaneous urticaria with or without angioedema is usually divided into ‘acute’ and ‘chronic’ forms. In ‘acute’ urticaria, the episode lasts up to six weeks. Chronic urticaria, by definition, lasts for more than six weeks.Urticaria is caused by the release of histamine from cells in the skin called mast cells.
A cohort study performed in a reputable cutaneous allergy centre in Berlin reports that the association between chronic urticaria and proven food allergy occurs in only 2 out of 100 people. Potential triggers for acute urticaria include the following: