“Urticaria is also called nettle rash or hives. It is characterized by extremely itchy raised lumps on the skin that appear in a random fashion and then resolve quite quickly without leaving a trace – the lumps can sometimes be seen visibly merging and migrating around the body. A proportion of people may also develop angioedema which occurs with deeper swellings that often involve the eye regions, lips, tongue, throat or genitals. Both urticaria and angioedema are caused by Histamine release. Of course the main question that people want to have answered is why they are releasing Histamine. Acute short lived episodes of urticaria/angioedema may occur as a result of an allergy to a food or a medication, or as the result of an underlying infection and can last between several hours and six weeks. Chronic urticaria is diagnosed if the rash persists or recurs for six weeks or longer. In such cases allergy is seldom the cause, as histamine release can occur in the absence of any underlying allergy. Several underlying “non allergic” causes may need to be excluded, but allergy tests are usually unhelpful.”