Urticaria, also known as hives, is an outbreak of swollen, pale red bumps or plaques (wheals) on the skin that appear suddenly -- either as a result of the body's reaction to certain allergens, or for unknown reasons. Hives usually cause itching, but may also burn or sting.
Hives/ Urticaria are a red, raised, itchy skin rash that is sometimes triggered by an allergen. An allergen is something that produces an allergic reaction.
It is also known as urticaria, welts, weals, or nettle rash.
When an allergic reaction occurs, the body releases a protein called histamine. When histamine is released, the tiny blood vessels known as capillaries leak fluid. The fluid accumulates in the skin and causes a rash.
Hives affect around 20 percent of people at some time in their life.
It is not contagious.
Urticaria is classified according to its duration.