‘Hives’, also known as urticaria, is the outbreak of pale red, swollen bumps on the body. It can occur on any part of the body including the face, back, arms or legs. It is a type of hypersensitivity reaction in which the cause for the reaction is idiopathic (unknown). Also, it can come in various shapes and sizes. Hives can be associated with redness, itching, and a burning and stinging sensation. These can last for more than a minute or even more than that; up to days.
What causes hives?
Most of the times, hives are idiopathic, i.e. the reason that causes this type of hypersensitivity reaction is unknown. The bumps are caused by the action of histamine that makes the plasma in the blood leak out of the small blood vessels. Histamine is a substance that is released from a specialized cell and is what causes allergic responses in general. There are three types of hives- namely, acute, chronic urticaria and physical urticaria. Acute urticaria is when the hives last for less than six weeks. Chronic urticaria occurs when the hives last for more than six weeks.
Physical urticaria refers to the condition when the hives are triggered due to causes such as heat, cold, sun exposure, sweating, pressure and exercise. Although, this condition is mainly idiopathic, there are common causes that may trigger this condition such as:
What are the symptoms of hives?
Hives are usually self-diagnosable. The various symptoms of urticaria are: