In the overwhelming majority of cases it is not "something" causing the chronic hives
, it is "nothing." That is, in about 95% of chronic hives
cases, the hives
are "idiopathic" (a medical term that means there is no discernible cause).
In about half of patients with chronic idiopathic hives
, the explanation is that body's immune system is, in a sense, overactive. The urticaria is "autoimmune".