In TCM it is held that urticaria is mostly due to weak constitution with deficiency of qi and blood, or prolonged illness that causes consumption of qi and blood. Such constitution can result in formation of wind due to blood deficiency, and intal-extal lack of resistance due to qi-deficiency, which gives chances to pathogenic wind to invade the body, hence the occurrence of urticaria. Therefore, this disease is a complicated one with deficiency in the origin and excessiveness of pathogen.