Chronic urticaria (CU) is a type of hives, also called nettle rash, that lasts for more than six weeks. Shorter bouts of hives are considered acute urticaria, and are treated differently.
Urticaria can be a manifestation of many conditions and illnesses, rather than one illness. Current research has shown that up to half of all CU is autoimmune, which means your body is making antibodies against itself, resulting in activation of basophils and mast cells. When these cells are activated, they release many different chemicals, including histamine, which results in hives, and in some people other allergy-like symptoms as well.
CIU stands for chronic idiopathic urticaria. The term idiopathic simply means ‘of unknown cause’. The diagnosis is often made by ruling out known causes, but some causes, like mastocytosis, cannot absolutely be ruled out. You will need to work with your doctor to rule out the things which can be ruled out, to find patterns by keeping a diary, and to find the medicine ‘cocktail’ which works most effectively for you.