Why do skin rashes (hives) appear? Unexpected factors you may not know about.
Hives is a skin condition characterized by the appearance of raised, red, itchy bumps (welts). They can vary in size and are often grouped together on different parts of the body, such as the face, arms, legs, and torso. Although these bumps usually disappear spontaneously within a few hours or days, they can sometimes recur and significantly affect a person’s quality of life .
How does hives appear?
Hives occur when certain cells in the body, called mast cells, release histamine and other chemicals into the bloodstream. This causes fluid to leak from the small blood vessels in the skin, causing the characteristic swelling and redness .
Main symptoms:
Raised, well-demarcated rashes, often with a pale center and a red border
Severe itching, which can range from mild to very intense
Rashes usually disappear within 24 hours without leaving any marks, but new ones may appear in other areas.
In some cases, hives may be accompanied by angioedema, which is swelling of the deeper layers of the skin, most often in the eyelids, lips, hands, feet, or genitals. If angioedema affects the throat or tongue and makes breathing difficult, it is a medical emergency .
Types of hives:
Acute urticaria: most common form, lasting less than 6 weeks, usually with a clear cause.
Chronic urticaria: Lasts more than six weeks, often without any obvious cause (idiopathic). In many cases, it is thought to be autoimmune in origin.
Induced (physical) urticaria: Caused by an external stimulus, for example:
Dermatographism (skin rash when scratched or rubbed)
Cold urticaria (due to cold)
Pressure urticaria (due to tight clothing)
Solar urticaria (due to the sun)
Cholinergic urticaria (due to increased body temperature – exercise, hot shower) 1
