Black and purple after cupping does not directly indicate a physical problem. Cupping is the use of negative pressure inside the jar, so that the jar adsorbed on the surface of the body acupuncture points or skin, so that the local congestion, bruising to produce benign stimulation. Cupping is often used to treat diseases, and in most cases is not used to diagnose diseases. Therefore, the color of cupping is not always of diagnostic value. The difference in color after cupping depends on the degree of adsorption of the can on the skin and the time of retention of the can. Generally speaking, if the adsorption strength of the can is light and the stay time is short, the skin will be flushed; while if the adsorption strength of the can is heavy and the stay time is long, the skin will be purplish-red, which is petechiae color. The degree of cupping should be chosen according to the needs of the condition, and should not be too heavy or repeated many times in pursuit of ecchymosis, so as to avoid injury.