Urticaria is an allergic disease that results from the temporary dilation of blood vessels under the mucous membranes of the skin and the exudation of their contents into the subcutaneous part of the skin, resulting in the formation of erythematous blotches or windswept bumps accompanied by an itching sensation. The erythema and the windmills that appear on the skin usually last for a few hours and disappear in no more than 24 hours. There are many factors that can cause urticaria, some from food, medication, hot and cold stimuli from the external environment, inhalation of pollen and flowers, infections, internal parasites, and some are caused by autoimmune diseases. The key to treating hives is to stay away from the triggers that cause hives.