What is urticaria?
Urticaria (hives) is characterised by pink or white weals (areas of raised skin) that are often itchy and surrounded by redness. Urticaria is often accompanied by angioedema which is deeper swelling in the skin caused by dilated blood vessels. Usually the individual weals clear within 24 hours without leaving a trace, but new weals may continue to develop for a prolonged period which can last weeks.
Urticaria is a result of mast cells (cells involved in the immune system) releasing a substance called histamine. The specific cause for this reaction is often not found but sometimes a trigger can be identified. Examples are infections, physical contact with an allergen (such as an animal), medication and sun exposure. In majority of cases urticaria is self-limited but may require treatment while active.
How is urticaria diagnosed?
The appearance of urticaria is usually sufficient for a diagnosis; finding the trigger may prove more challenging and in many cases there are no specific triggers. No specific test exists to identify the cause but if a certain trigger is suspected, a specific blood test for antibodies or a skin prick test may be performed for confirmation. Food diaries may help in finding potential culprits.
How is it treated?
Avoiding any potential triggers will be helpful in the long term. Histamine release causes the symptoms associated with urticaria, therefore antihistamine tablets are effective for symptom relief. Individuals respond differently to various antihistamines and often a combination of prescribed and over the counter antihistamines are needed to control the symptoms. Other options are oral steroids or even biological injections which are available in specialist centres.