Hives are also known as urticaria. They are very itchy rashes and appears like mosquito bites. They can recur, and comes and goes. Hives is due to release of histamine onto the skin from some, very often unknown triggers.
In the more acute setting, hives may be associated with allergy, and blood tests or skin prick tests may be warranted.
It can run a chronic path with possible triggers of heat, cold, sweat, pressure, sunlight, exercise or even food.
Sometimes, it is associated with underlying medical conditions such as anaemia or thyroid problems.