Hives, also known as Urticaria in Western medicine. In Traditional Chinese medicine it is called "rubella" and "hidden rash", commonly known as "ghost rice pimple" or "rubella". Urticaria, caused by various reasons, is a kind of skin mucous membrane reactive disease, and is characterized by the hidden, edged, clear, red or white pruritus wheals. Its clinical symptoms are often first itchy skin, then the wheals, showing bright red, pale and skin color. A few cases are only edematous erythema. The attack time of wheals with different sizes and forms are irregular. The wheal is gradually spreads and mixes together. Because of dermal papillary edema, the epidermal follicle is hollow. The wheal lasts for several minutes to several hours, and can fade away within a few days without leaving a trace. It can happen repeatedly or in batches, more often at nightfall. The causes of urticaria are complex, with about three-quarters of patients unable to find a cause, especially chronic urticarial (CU).