Congestion generally refers to the presence of increased blood levels in the blood vessels of tissues as well as organs. Congestion can be categorized as arterial or venous according to its mechanism of occurrence. The causes of congestion are many, generally in addition to inflammation, there are some warm, mechanical, chemical and mental stimuli can be triggered, these stimuli through the vasodilator nerve excitation or vasoconstrictor nerve paralysis and lead to congestion. 1. Arterial congestion: also known as active congestion or congestion, refers to the expansion of small arteries to increase the amount of blood flow into the tissues, arterial congestion of a short period of time, beneficial to the body, known as physiological congestion, such as: skin congestion after a hot bath, gastric mucosal congestion after meals, etc. Pathological arterial congestion is seen in inflammatory congestion. 2. Venous congestion: also known as passive congestion or bruising, refers to the venous blood drainage from the tissue is reduced, blood stasis in small veins and capillaries, bruising due to hypoxia, tissue metabolism and intermediate metabolite accumulation, the light cause local parenchymal cell degeneration, the corresponding morphological changes and functional reduction, the serious case can cause local necrosis of the tissue. When there is congestion should be timely to the regular hospital, do not be negligent or blindly dealt with, to avoid delaying the condition.