Hives, also known as urticaria, is a condition where the skin becomes inflamed and itchy. Hives can be caused by a number of triggers, both food or environmental, which result in the release of histamine by the body’s immune system. Hives affect the superficial layers of the skin, when the deeper layers of the skin are involved the condition is referred to as angioedema or swelling. The two conditions frequently occur together. In most cases, the cause is unknown or spontaneous.